diff --git a/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64/digidocpp.framework/Headers/crypto/X509Cert.h b/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64/digidocpp.framework/Headers/crypto/X509Cert.h
index f6b81962..d0776490 100644
--- a/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64/digidocpp.framework/Headers/crypto/X509Cert.h
+++ b/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64/digidocpp.framework/Headers/crypto/X509Cert.h
@@ -96,6 +96,7 @@ namespace digidoc
           std::vector<std::string> qcStatements() const;
           bool isCA() const;
           bool isValid(time_t *t = nullptr) const;
+          bool verify(bool noqscd, tm validation_time = {}) const;
 
           X509* handle() const;
           operator std::vector<unsigned char>() const;
diff --git a/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64/digidocpp.framework/Info.plist b/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64/digidocpp.framework/Info.plist
index cb99f7de..a9d4f167 100644
--- a/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64/digidocpp.framework/Info.plist
+++ b/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64/digidocpp.framework/Info.plist
@@ -17,11 +17,11 @@
 	<key>CFBundlePackageType</key>
 	<string>FMWK</string>
 	<key>CFBundleShortVersionString</key>
-	<string>4.3.0</string>
+	<string>4.4.0</string>
 	<key>CFBundleSignature</key>
 	<string>????</string>
 	<key>CFBundleVersion</key>
-	<string>46</string>
+	<string>48</string>
 	<key>CSResourcesFileMapped</key>
 	<true/>
 	<key>MinimumOSVersion</key>
diff --git a/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64/digidocpp.framework/digidocpp b/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64/digidocpp.framework/digidocpp
index 26358d78..8dae6632 100755
Binary files a/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64/digidocpp.framework/digidocpp and b/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64/digidocpp.framework/digidocpp differ
diff --git a/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64_x86_64-simulator/digidocpp.framework/Headers/crypto/X509Cert.h b/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64_x86_64-simulator/digidocpp.framework/Headers/crypto/X509Cert.h
index f6b81962..d0776490 100644
--- a/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64_x86_64-simulator/digidocpp.framework/Headers/crypto/X509Cert.h
+++ b/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64_x86_64-simulator/digidocpp.framework/Headers/crypto/X509Cert.h
@@ -96,6 +96,7 @@ namespace digidoc
           std::vector<std::string> qcStatements() const;
           bool isCA() const;
           bool isValid(time_t *t = nullptr) const;
+          bool verify(bool noqscd, tm validation_time = {}) const;
 
           X509* handle() const;
           operator std::vector<unsigned char>() const;
diff --git a/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64_x86_64-simulator/digidocpp.framework/Info.plist b/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64_x86_64-simulator/digidocpp.framework/Info.plist
index cb99f7de..a9d4f167 100644
--- a/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64_x86_64-simulator/digidocpp.framework/Info.plist
+++ b/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64_x86_64-simulator/digidocpp.framework/Info.plist
@@ -17,11 +17,11 @@
 	<key>CFBundlePackageType</key>
 	<string>FMWK</string>
 	<key>CFBundleShortVersionString</key>
-	<string>4.3.0</string>
+	<string>4.4.0</string>
 	<key>CFBundleSignature</key>
 	<string>????</string>
 	<key>CFBundleVersion</key>
-	<string>46</string>
+	<string>48</string>
 	<key>CSResourcesFileMapped</key>
 	<true/>
 	<key>MinimumOSVersion</key>
diff --git a/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64_x86_64-simulator/digidocpp.framework/digidocpp b/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64_x86_64-simulator/digidocpp.framework/digidocpp
index 7089aa70..de4899c2 100755
Binary files a/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64_x86_64-simulator/digidocpp.framework/digidocpp and b/Modules/LibdigidocLib/Sources/LibdigidocObjC/Libs/digidocpp.xcframework/ios-arm64_x86_64-simulator/digidocpp.framework/digidocpp differ
diff --git a/Modules/LibdigidocLib/Sources/LibdigidocObjC/include/Container/DigiDocContainerWrapper.h b/Modules/LibdigidocLib/Sources/LibdigidocObjC/include/Container/DigiDocContainerWrapper.h
index ff85448e..59a67a4f 100644
--- a/Modules/LibdigidocLib/Sources/LibdigidocObjC/include/Container/DigiDocContainerWrapper.h
+++ b/Modules/LibdigidocLib/Sources/LibdigidocObjC/include/Container/DigiDocContainerWrapper.h
@@ -39,6 +39,9 @@ NS_ASSUME_NONNULL_BEGIN
 + (NSString *)libdigidocppVersion;
 + (NSString *)mediaType;
 
++ (void)extendLastSignatureToLTA:(NSString *)containerPath completion:(void (^)(NSError * _Nullable error))completion;
++ (void)extendAllSignaturesToLTA:(NSString *)containerPath completion:(void (^)(NSError * _Nullable error))completion;
+
 @end
 
 NS_ASSUME_NONNULL_END
diff --git a/Modules/LibdigidocLib/Sources/LibdigidocObjC/include/Container/DigiDocContainerWrapper.mm b/Modules/LibdigidocLib/Sources/LibdigidocObjC/include/Container/DigiDocContainerWrapper.mm
index b101549c..33ff0868 100644
--- a/Modules/LibdigidocLib/Sources/LibdigidocObjC/include/Container/DigiDocContainerWrapper.mm
+++ b/Modules/LibdigidocLib/Sources/LibdigidocObjC/include/Container/DigiDocContainerWrapper.mm
@@ -86,6 +86,7 @@ + (NSData *)getNSDataFromVector:(const std::vector<unsigned char>&)vectorData {
     return [NSData dataWithBytes:vectorData.data() length:vectorData.size()];
 }
 
+
 + (DigiDocSignatureStatus)determineSignatureStatus:(int)status {
     typedef digidoc::Signature::Validator::Status Status;
 
@@ -133,6 +134,16 @@ + (DigiDocSignature *)getSignature:(digidoc::Signature *)signature pos:(int)pos
     digiDocSignature.messageImprint = [NSData dataWithBytes:signature->messageImprint().data() length:signature->messageImprint().size()];
     digiDocSignature.trustedSigningTime = [NSString stringWithUTF8String:signature->trustedSigningTime().c_str()];
 
+    auto archiveTimestamps = signature->ArchiveTimeStamps();
+    if (!archiveTimestamps.empty()) {
+        const auto& firstTS = archiveTimestamps.front();
+        digiDocSignature.archiveTimestampTime = [NSString stringWithUTF8String:firstTS.time.c_str()];
+        digiDocSignature.archiveTimestampCert = [DigiDocContainerWrapper getNSDataFromVector:firstTS.cert];
+    } else {
+        digiDocSignature.archiveTimestampTime = @"";
+        digiDocSignature.archiveTimestampCert = [NSData data];
+    }
+
     std::vector<std::string> signerRoles = signature->signerRoles();
     NSMutableArray* signerRolesList = [NSMutableArray arrayWithCapacity: signerRoles.size()];
     for (auto const& signerRole: signerRoles) {
@@ -358,5 +369,31 @@ + (void)removeDataFileFromContainerWithPath:(NSString *)containerPath atIndex:(N
     } completion:completion];
 }
 
++ (void)extendLastSignatureToLTA:(NSString *)containerPath completion:(void (^)(NSError * _Nullable error))completion {
+    [self open:containerPath validateOnline:YES command:^(digidoc::Container &container) {
+        auto sigs = container.signatures();
+        if (!sigs.empty()) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+            sigs.back()->extendSignatureProfile("time-stamp-archive");
+#pragma clang diagnostic pop
+        }
+        container.save(containerPath.UTF8String);
+    } completion:completion];
+}
+
++ (void)extendAllSignaturesToLTA:(NSString *)containerPath completion:(void (^)(NSError * _Nullable error))completion {
+    [self open:containerPath validateOnline:YES command:^(digidoc::Container &container) {
+        auto sigs = container.signatures();
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+        for (auto *sig : sigs) {
+            sig->extendSignatureProfile("time-stamp-archive");
+        }
+#pragma clang diagnostic pop
+        container.save(containerPath.UTF8String);
+    } completion:completion];
+}
+
 
 @end
diff --git a/Modules/LibdigidocLib/Sources/LibdigidocObjC/include/Model/DigiDocSignature.h b/Modules/LibdigidocLib/Sources/LibdigidocObjC/include/Model/DigiDocSignature.h
index da66b2f6..bdb2b350 100644
--- a/Modules/LibdigidocLib/Sources/LibdigidocObjC/include/Model/DigiDocSignature.h
+++ b/Modules/LibdigidocLib/Sources/LibdigidocObjC/include/Model/DigiDocSignature.h
@@ -52,5 +52,8 @@ typedef NS_ENUM(int, DigiDocSignatureStatus) {
 @property (nonatomic, assign) DigiDocSignatureStatus status;
 @property (nonatomic, strong) NSString *diagnosticsInfo;
 
+@property (nonatomic, strong) NSString *archiveTimestampTime;
+@property (nonatomic, strong) NSData *archiveTimestampCert;
+
 @end
 
diff --git a/Modules/LibdigidocLib/Sources/LibdigidocSwift/Domain/Container/ContainerWrapper.swift b/Modules/LibdigidocLib/Sources/LibdigidocSwift/Domain/Container/ContainerWrapper.swift
index ce3cc7c8..05c26365 100644
--- a/Modules/LibdigidocLib/Sources/LibdigidocSwift/Domain/Container/ContainerWrapper.swift
+++ b/Modules/LibdigidocLib/Sources/LibdigidocSwift/Domain/Container/ContainerWrapper.swift
@@ -263,6 +263,44 @@ public actor ContainerWrapper: ContainerWrapperProtocol, Loggable {
         }
     }
 
+    @discardableResult
+    public func extendSignatureToLTA(containerFile: URL) async throws -> ContainerWrapperProtocol {
+        do {
+            try await withCheckedThrowingContinuation { (continuation: CheckedContinuation<Void, Error>) in
+                DigiDocContainerWrapper.extendLastSignature(toLTA: containerFile.resolvedPath) { error in
+                    if let error = error {
+                        continuation.resume(throwing: error)
+                    } else {
+                        continuation.resume()
+                    }
+                }
+            }
+            return try await open(containerFile: containerFile, isSivaConfirmed: true)
+        } catch {
+            let nsError = (error as NSError?) ?? NSError(domain: "ContainerWrapper - cannot extend signature to LTA", code: 8)
+            throw DigiDocError.signatureExtensionFailed(ErrorDetail(nsError: nsError))
+        }
+    }
+
+    @discardableResult
+    public func extendSignaturesToLTA(containerFile: URL) async throws -> ContainerWrapperProtocol {
+        do {
+            try await withCheckedThrowingContinuation { (continuation: CheckedContinuation<Void, Error>) in
+                DigiDocContainerWrapper.extendAllSignatures(toLTA: containerFile.resolvedPath) { error in
+                    if let error = error {
+                        continuation.resume(throwing: error)
+                    } else {
+                        continuation.resume()
+                    }
+                }
+            }
+            return try await open(containerFile: containerFile, isSivaConfirmed: true)
+        } catch {
+            let nsError = (error as NSError?) ?? NSError(domain: "ContainerWrapper - cannot extend signatures to LTA", code: 9)
+            throw DigiDocError.signatureExtensionFailed(ErrorDetail(nsError: nsError))
+        }
+    }
+
     private static func signatureStatusToDigiDocStatus(_ status: DigiDocSignatureStatus) -> SignatureStatus {
         switch status {
         case .Valid:
@@ -339,7 +377,9 @@ public actor ContainerWrapper: ContainerWrapperProtocol, Loggable {
                 status: signatureStatusToDigiDocStatus(signature.status),
                 format: signature.format,
                 messageImprint: signature.messageImprint,
-                diagnosticsInfo: signature.diagnosticsInfo
+                diagnosticsInfo: signature.diagnosticsInfo,
+                archiveTimestampTime: signature.archiveTimestampTime,
+                archiveTimestampCert: signature.archiveTimestampCert
             )
         }
     }
diff --git a/Modules/LibdigidocLib/Sources/LibdigidocSwift/Domain/Container/ContainerWrapperProtocol.swift b/Modules/LibdigidocLib/Sources/LibdigidocSwift/Domain/Container/ContainerWrapperProtocol.swift
index 316f52b6..ef238947 100644
--- a/Modules/LibdigidocLib/Sources/LibdigidocSwift/Domain/Container/ContainerWrapperProtocol.swift
+++ b/Modules/LibdigidocLib/Sources/LibdigidocSwift/Domain/Container/ContainerWrapperProtocol.swift
@@ -39,6 +39,8 @@ public protocol ContainerWrapperProtocol: Sendable {
         userAgent: String
     ) async throws -> Data
     func addSignature(signature: Data, containerFile: URL) async throws -> ContainerWrapperProtocol
+    @discardableResult func extendSignatureToLTA(containerFile: URL) async throws -> ContainerWrapperProtocol
+    @discardableResult func extendSignaturesToLTA(containerFile: URL) async throws -> ContainerWrapperProtocol
 }
 
 extension ContainerWrapperProtocol {
diff --git a/Modules/LibdigidocLib/Sources/LibdigidocSwift/Domain/Models/SignatureWrapper.swift b/Modules/LibdigidocLib/Sources/LibdigidocSwift/Domain/Models/SignatureWrapper.swift
index 5cb616cc..d8586404 100644
--- a/Modules/LibdigidocLib/Sources/LibdigidocSwift/Domain/Models/SignatureWrapper.swift
+++ b/Modules/LibdigidocLib/Sources/LibdigidocSwift/Domain/Models/SignatureWrapper.swift
@@ -52,6 +52,13 @@ public struct SignatureWrapper: Sendable, Identifiable, Hashable {
     public var status: SignatureStatus
     public var diagnosticsInfo: String
 
+    public var archiveTimestampTime: String
+    public var archiveTimestampCert: Data
+
+    public var isLTAExtended: Bool {
+        !archiveTimestampCert.isEmpty
+    }
+
     public init(pos: Int,
                 signingCert: Data,
                 timestampCert: Data,
@@ -71,7 +78,9 @@ public struct SignatureWrapper: Sendable, Identifiable, Hashable {
                 status: SignatureStatus = .unknown,
                 format: String,
                 messageImprint: Data,
-                diagnosticsInfo: String) {
+                diagnosticsInfo: String,
+                archiveTimestampTime: String = "",
+                archiveTimestampCert: Data = Data()) {
         self.pos = pos
         self.signingCert = signingCert
         self.timestampCert = timestampCert
@@ -92,5 +101,7 @@ public struct SignatureWrapper: Sendable, Identifiable, Hashable {
         self.format = format
         self.messageImprint = messageImprint
         self.diagnosticsInfo = diagnosticsInfo
+        self.archiveTimestampTime = archiveTimestampTime
+        self.archiveTimestampCert = archiveTimestampCert
     }
 }
diff --git a/Modules/LibdigidocLib/Sources/LibdigidocSwift/Errors/DigiDocError.swift b/Modules/LibdigidocLib/Sources/LibdigidocSwift/Errors/DigiDocError.swift
index a99ecdcd..0da82e19 100644
--- a/Modules/LibdigidocLib/Sources/LibdigidocSwift/Errors/DigiDocError.swift
+++ b/Modules/LibdigidocLib/Sources/LibdigidocSwift/Errors/DigiDocError.swift
@@ -31,6 +31,7 @@ public enum DigiDocError: Error {
     case signatureRemovingFailed(ErrorDetail)
     case dataFileRemovingFailed(ErrorDetail)
     case signatureAddingFailed(ErrorDetail)
+    case signatureExtensionFailed(ErrorDetail)
 
     public var errorDetail: ErrorDetail {
         switch self {
@@ -43,7 +44,8 @@ public enum DigiDocError: Error {
                 .containerDataFileSavingFailed(let errorDetail),
                 .signatureRemovingFailed(let errorDetail),
                 .dataFileRemovingFailed(let errorDetail),
-                .signatureAddingFailed(let errorDetail):
+                .signatureAddingFailed(let errorDetail),
+                .signatureExtensionFailed(let errorDetail):
             return errorDetail
 
         case .alreadyInitialized:
diff --git a/Modules/LibdigidocLib/Sources/LibdigidocSwift/SignedContainer.swift b/Modules/LibdigidocLib/Sources/LibdigidocSwift/SignedContainer.swift
index e9056715..1e63272c 100644
--- a/Modules/LibdigidocLib/Sources/LibdigidocSwift/SignedContainer.swift
+++ b/Modules/LibdigidocLib/Sources/LibdigidocSwift/SignedContainer.swift
@@ -291,6 +291,42 @@ public actor SignedContainer: SignedContainerProtocol, Loggable {
             containerUtil: containerUtil
         )
     }
+
+    @discardableResult
+    public func extendSignature() async throws -> SignedContainerProtocol {
+        guard let containerFile else {
+            throw DigiDocError.signatureExtensionFailed(
+                ErrorDetail(message: "Cannot extend signature: container file is nil", code: 0)
+            )
+        }
+        let containerWrapper = try await container.extendSignatureToLTA(containerFile: containerFile)
+        return SignedContainer(
+            containerFile: containerFile,
+            isExistingContainer: true,
+            container: containerWrapper,
+            timestamps: timestamps,
+            fileManager: fileManager,
+            containerUtil: containerUtil
+        )
+    }
+
+    @discardableResult
+    public func extendSignatures() async throws -> SignedContainerProtocol {
+        guard let containerFile else {
+            throw DigiDocError.signatureExtensionFailed(
+                ErrorDetail(message: "Cannot extend signatures: container file is nil", code: 0)
+            )
+        }
+        let containerWrapper = try await container.extendSignaturesToLTA(containerFile: containerFile)
+        return SignedContainer(
+            containerFile: containerFile,
+            isExistingContainer: true,
+            container: containerWrapper,
+            timestamps: timestamps,
+            fileManager: fileManager,
+            containerUtil: containerUtil
+        )
+    }
 }
 
 extension SignedContainer {
diff --git a/Modules/LibdigidocLib/Sources/LibdigidocSwift/SignedContainerProtocol.swift b/Modules/LibdigidocLib/Sources/LibdigidocSwift/SignedContainerProtocol.swift
index a19741d4..94ad3f88 100644
--- a/Modules/LibdigidocLib/Sources/LibdigidocSwift/SignedContainerProtocol.swift
+++ b/Modules/LibdigidocLib/Sources/LibdigidocSwift/SignedContainerProtocol.swift
@@ -52,10 +52,19 @@ public protocol SignedContainerProtocol: GeneralContainer, Sendable {
         userAgent: String
     ) async throws -> Data
     func addSignature(signature: Data, containerFile: URL) async throws -> SignedContainerProtocol
+    @discardableResult func extendSignature() async throws -> SignedContainerProtocol
+    @discardableResult func extendSignatures() async throws -> SignedContainerProtocol
 }
 
 extension SignedContainerProtocol {
     func saveDataFile(dataFile: DataFileWrapper) async throws -> URL {
         try await saveDataFile(dataFile: dataFile, to: nil)
     }
+
+    public func extendSignatureIfEnabled(_ enabled: Bool) async throws -> any SignedContainerProtocol {
+        guard enabled else { return self }
+        let mimetype = await getContainerMimetype()
+        guard mimetype != CommonsLib.Constants.MimeType.Ddoc else { return self }
+        return try await extendSignature()
+    }
 }
diff --git a/RIADigiDoc/DI/AppContainer.swift b/RIADigiDoc/DI/AppContainer.swift
index bc7eb482..afdb65c4 100644
--- a/RIADigiDoc/DI/AppContainer.swift
+++ b/RIADigiDoc/DI/AppContainer.swift
@@ -357,6 +357,15 @@ extension Container {
         }
     }
 
+    @MainActor
+    var ltaSettingsViewModel: Factory<LTASettingsViewModel> {
+        self { @MainActor in
+            LTASettingsViewModel(
+                dataStore: self.dataStore()
+            )
+        }
+    }
+
     var signatureUtil: Factory<SignatureUtilProtocol> {
         self { SignatureUtil() }
     }
diff --git a/RIADigiDoc/Domain/Model/Settings/SigningServicesSettingsViewTab.swift b/RIADigiDoc/Domain/Model/Settings/SigningServicesSettingsViewTab.swift
index 1570e705..98bed9c5 100644
--- a/RIADigiDoc/Domain/Model/Settings/SigningServicesSettingsViewTab.swift
+++ b/RIADigiDoc/Domain/Model/Settings/SigningServicesSettingsViewTab.swift
@@ -20,4 +20,5 @@
 enum SigningServicesSettingsViewTab: Int, Sendable {
     case timestampServices = 0
     case mobileIdAndSmartId = 1
+    case lta = 2
 }
diff --git a/RIADigiDoc/Domain/Preferences/DataStore.swift b/RIADigiDoc/Domain/Preferences/DataStore.swift
index 185ad081..daf6b1fb 100644
--- a/RIADigiDoc/Domain/Preferences/DataStore.swift
+++ b/RIADigiDoc/Domain/Preferences/DataStore.swift
@@ -505,6 +505,16 @@ public actor DataStore: DataStoreProtocol {
         userDefaults().set(isAlwaysEnabled, forKey: Keys.isCrashlyticsAlwaysEnabled)
     }
 
+    // MARK: - LTA Settings
+
+    public func getIsDefaultLTAEnabled() async -> Bool {
+        userDefaults().bool(forKey: Keys.isDefaultLTAEnabled)
+    }
+
+    public func setIsDefaultLTAEnabled(_ isEnabled: Bool) async {
+        userDefaults().set(isEnabled, forKey: Keys.isDefaultLTAEnabled)
+    }
+
     // MARK: - Migration
     public func getIsRecentDocumentsMigrationDone() async -> Bool {
         userDefaults().bool(forKey: Keys.isRecentDocumentsMigrationDone)
@@ -581,5 +591,6 @@ public actor DataStore: DataStoreProtocol {
         static let isLogFileSaved = "isLogFileSaved"
         static let isCrashlyticsAlwaysEnabled = "isCrashlyticsAlwaysEnabled"
         static let isRecentDocumentsMigrationDone = "isRecentDocumentsMigrationDone"
+        static let isDefaultLTAEnabled = "isDefaultLTAEnabled"
     }
 }
diff --git a/RIADigiDoc/Domain/Preferences/DataStoreProtocol.swift b/RIADigiDoc/Domain/Preferences/DataStoreProtocol.swift
index c0591299..06f0dd51 100644
--- a/RIADigiDoc/Domain/Preferences/DataStoreProtocol.swift
+++ b/RIADigiDoc/Domain/Preferences/DataStoreProtocol.swift
@@ -123,6 +123,10 @@ public protocol DataStoreProtocol: Sendable {
     func getIsCrashlyticsAlwaysEnabled() async -> Bool
     func setIsCrashlyticsAlwaysEnabled(_ isEnabled: Bool) async
 
+    // MARK: - LTA Settings
+    func getIsDefaultLTAEnabled() async -> Bool
+    func setIsDefaultLTAEnabled(_ isEnabled: Bool) async
+
     // MARK: - Migration
     func getIsRecentDocumentsMigrationDone() async -> Bool
     func setIsRecentDocumentsMigrationDone(_ isDone: Bool) async
diff --git a/RIADigiDoc/Supporting files/Localizable.xcstrings b/RIADigiDoc/Supporting files/Localizable.xcstrings
index 03b639f8..62869247 100644
--- a/RIADigiDoc/Supporting files/Localizable.xcstrings	
+++ b/RIADigiDoc/Supporting files/Localizable.xcstrings	
@@ -127,6 +127,78 @@
         }
       }
     },
+    "Archive timestamp" : {
+      "comment" : "Archive timestamp label in signature details",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Archive timestamp"
+          }
+        },
+        "et" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Arhiivi ajatempel"
+          }
+        }
+      }
+    },
+    "Archive timestamp valid until" : {
+      "comment" : "Archive timestamp valid until badge text",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Archive timestamp valid until: %@"
+          }
+        },
+        "et" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Arhiivi ajatempel kehtib kuni: %@"
+          }
+        }
+      }
+    },
+    "Archive TS Certificate" : {
+      "comment" : "Archive TS certificate label in signature details",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Archive TS Certificate"
+          }
+        },
+        "et" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Arhiivi TS sertifikaat"
+          }
+        }
+      }
+    },
+    "Archive TS Certificate issuer" : {
+      "comment" : "Archive TS certificate issuer label in signature details",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Archive TS Certificate issuer"
+          }
+        },
+        "et" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Arhiivi TS sertifikaadi väljaandja"
+          }
+        }
+      }
+    },
     "Authentication certificate" : {
       "comment" : "My eID PIN 1 title",
       "extractionState" : "manual",
@@ -1691,6 +1763,78 @@
         }
       }
     },
+    "Extend" : {
+      "comment" : "Confirm button label in extend signatures dialog",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Extend"
+          }
+        },
+        "et" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Pikenda"
+          }
+        }
+      }
+    },
+    "Extend signatures" : {
+      "comment" : "Button label for extending signatures to LTA",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Extend signatures"
+          }
+        },
+        "et" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Pikenda allkirju"
+          }
+        }
+      }
+    },
+    "Extend signatures confirm message" : {
+      "comment" : "Confirmation dialog message shown before extending signatures to LTA",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "All signatures in the container will be extended to LTA format."
+          }
+        },
+        "et" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Kõik ümbriku allkirjad pikendatakse LTA formaati."
+          }
+        }
+      }
+    },
+    "Extending signatures failed" : {
+      "comment" : "Shown as Toast when extending signatures to LTA fails",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Failed to extend signature(s)"
+          }
+        },
+        "et" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Allkirja(de) pikendamine ebaõnnestus"
+          }
+        }
+      }
+    },
     "Failed mobile-ID transaction" : {
       "comment" : "Mobile-ID error for signatureHashMismatch",
       "extractionState" : "manual",
@@ -4128,6 +4272,42 @@
         }
       }
     },
+    "Main settings default lta disabled" : {
+      "comment" : "Main settings default lta disabled",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Do not use LTA format by default when signing"
+          }
+        },
+        "et" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Ei kasuta vaikimisi LTAd allkirjastamisel"
+          }
+        }
+      }
+    },
+    "Main settings default lta title" : {
+      "comment" : "Main settings default lta title",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Use LTA format by default when signing"
+          }
+        },
+        "et" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Kasuta vaikimisi LTAd allkirjastamisel"
+          }
+        }
+      }
+    },
     "Main settings default manual access title" : {
       "comment" : "Main settings default manual access title",
       "extractionState" : "manual",
@@ -4164,6 +4344,24 @@
         }
       }
     },
+    "Main settings lta tab title" : {
+      "comment" : "Tab title for LTA settings in Signing services",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "LTA"
+          }
+        },
+        "et" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "LTA"
+          }
+        }
+      }
+    },
     "Main settings menu advanced" : {
       "comment" : "Main settings menu advanced",
       "extractionState" : "manual",
@@ -7290,6 +7488,24 @@
         }
       }
     },
+    "Signatures extended" : {
+      "comment" : "Shown as Toast when extending signatures to LTA succeeds",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Signature(s) extended successfully"
+          }
+        },
+        "et" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Allkirja(de) pikendamine õnnestus"
+          }
+        }
+      }
+    },
     "Signed at" : {
       "comment" : "Signed date and time",
       "extractionState" : "manual",
diff --git a/RIADigiDoc/UI/Component/Bottom Sheet/ContainerNameBottomSheetActions.swift b/RIADigiDoc/UI/Component/Bottom Sheet/ContainerNameBottomSheetActions.swift
index 832fbd78..0ae11f50 100644
--- a/RIADigiDoc/UI/Component/Bottom Sheet/ContainerNameBottomSheetActions.swift	
+++ b/RIADigiDoc/UI/Component/Bottom Sheet/ContainerNameBottomSheetActions.swift	
@@ -24,10 +24,12 @@ struct ContainerNameBottomSheetActions {
         isSaveButtonShown: Bool = true,
         isSignButtonShown: Bool,
         isEncryptButtonShown: Bool,
+        isExtendSignaturesButtonShown: Bool,
         onRenameContainerButtonClick: @escaping () -> Void,
         onSaveContainerButtonClick: @escaping () -> Void,
         onSignContainerButtonClick: @escaping () -> Void,
-        onEncryptContainerButtonClick: @escaping () -> Void
+        onEncryptContainerButtonClick: @escaping () -> Void,
+        onExtendSignaturesClick: @escaping () -> Void
     ) -> [BottomSheetButton] {
         [
             BottomSheetButton(
@@ -59,6 +61,14 @@ struct ContainerNameBottomSheetActions {
                 accessibilityLabel: "Sign document",
                 showExtraIcon: true,
                 onClick: onSignContainerButtonClick
+            ),
+            BottomSheetButton(
+                showButton: isExtendSignaturesButtonShown,
+                icon: "ic_m3_more_time_48pt_wght400",
+                title: "Extend signatures",
+                accessibilityLabel: "Extend signatures",
+                showExtraIcon: false,
+                onClick: onExtendSignaturesClick
             )
         ]
     }
diff --git a/RIADigiDoc/UI/Component/Container/ContainerNameView.swift b/RIADigiDoc/UI/Component/Container/ContainerNameView.swift
index 65a52ef8..158d8b4e 100644
--- a/RIADigiDoc/UI/Component/Container/ContainerNameView.swift
+++ b/RIADigiDoc/UI/Component/Container/ContainerNameView.swift
@@ -41,6 +41,7 @@ struct ContainerNameView: View {
     let isSaveButtonShown: Bool
     let isSignButtonShown: Bool
     let isEncryptButtonShown: Bool
+    let isExtendSignaturesButtonShown: Bool
     let showLeftActionButton: Bool
     let showRightActionButton: Bool
     let leftActionButtonName: String
@@ -53,6 +54,7 @@ struct ContainerNameView: View {
     let onRenameContainerButtonClick: () -> Void
     let onSignContainerButtonClick: () -> Void
     let onEncryptContainerButtonClick: () -> Void
+    let onExtendSignaturesClick: () -> Void
 
     private var bottomSheetActions: [BottomSheetButton] {
         ContainerNameBottomSheetActions.actions(
@@ -60,10 +62,12 @@ struct ContainerNameView: View {
             isSaveButtonShown: isSaveButtonShown,
             isSignButtonShown: isSignButtonShown,
             isEncryptButtonShown: isEncryptButtonShown,
+            isExtendSignaturesButtonShown: isExtendSignaturesButtonShown,
             onRenameContainerButtonClick: onRenameContainerButtonClick,
             onSaveContainerButtonClick: onSaveContainerButtonClick,
             onSignContainerButtonClick: onSignContainerButtonClick,
-            onEncryptContainerButtonClick: onEncryptContainerButtonClick
+            onEncryptContainerButtonClick: onEncryptContainerButtonClick,
+            onExtendSignaturesClick: onExtendSignaturesClick
         )
     }
 
@@ -169,6 +173,7 @@ struct ContainerNameView: View {
         isSaveButtonShown: true,
         isSignButtonShown: true,
         isEncryptButtonShown: false,
+        isExtendSignaturesButtonShown: true,
         showLeftActionButton: true,
         showRightActionButton: true,
         leftActionButtonName: "Sign",
@@ -180,7 +185,8 @@ struct ContainerNameView: View {
         onSaveContainerButtonClick: {},
         onRenameContainerButtonClick: {},
         onSignContainerButtonClick: {},
-        onEncryptContainerButtonClick: {}
+        onEncryptContainerButtonClick: {},
+        onExtendSignaturesClick: {}
     )
     .environment(Container.shared.languageSettings())
     .environment(Container.shared.themeSettings())
diff --git a/RIADigiDoc/UI/Component/Container/Crypto/EncryptView.swift b/RIADigiDoc/UI/Component/Container/Crypto/EncryptView.swift
index cafd2b14..2af43f33 100644
--- a/RIADigiDoc/UI/Component/Container/Crypto/EncryptView.swift
+++ b/RIADigiDoc/UI/Component/Container/Crypto/EncryptView.swift
@@ -211,6 +211,7 @@ struct EncryptView: View {
                                     isSaveButtonShown: viewModel.isContainerEncrypted || viewModel.isContainerDecrypted,
                                     isSignButtonShown: viewModel.isSignButtonShown,
                                     isEncryptButtonShown: false,
+                                    isExtendSignaturesButtonShown: false,
                                     showLeftActionButton: false,
                                     showRightActionButton: viewModel.isEncryptButtonShown ||
                                         viewModel.isDecryptButtonShown,
@@ -262,6 +263,9 @@ struct EncryptView: View {
                                     },
                                     onEncryptContainerButtonClick: {
                                         // Do nothing
+                                    },
+                                    onExtendSignaturesClick: {
+                                        // Do nothing
                                     }
                                 )
                                 .background(
diff --git a/RIADigiDoc/UI/Component/Container/SignatureDetailView.swift b/RIADigiDoc/UI/Component/Container/SignatureDetailView.swift
index 5ec90543..90a556e8 100644
--- a/RIADigiDoc/UI/Component/Container/SignatureDetailView.swift
+++ b/RIADigiDoc/UI/Component/Container/SignatureDetailView.swift
@@ -117,6 +117,14 @@ struct SignatureDetailView: View {
         return "\(mobileTime.date) \(mobileTime.time)"
     }
 
+    var archiveTimestampTime: String {
+        let ts = DateUtil.getFormattedDateTime(
+            dateTimeString: signature.archiveTimestampTime,
+            isUTC: false
+        )
+        return "\(ts.date) \(ts.time)"
+    }
+
     init(
         certificateDetailViewModel: CertificateDetailViewModel = Container.shared.certificateDetailViewModel(),
         signature: SignatureWrapper,
@@ -323,6 +331,36 @@ struct SignatureDetailView: View {
                                                 value: signersMobileTime
                                             )
                                         )
+
+                                        if !isTimestamp && signature.isLTAExtended {
+                                            SignerDetailView(
+                                                signatureDataItem: SignatureDataItem(
+                                                    title: languageSettings.localized("Archive timestamp"),
+                                                    value: archiveTimestampTime
+                                                )
+                                            )
+
+                                            SignerDetailView(
+                                                signatureDataItem: SignatureDataItem(
+                                                    title: languageSettings.localized("Archive TS Certificate issuer"),
+                                                    value: viewModel.getIssuerName(cert: signature.archiveTimestampCert)
+                                                )
+                                            )
+
+                                            NavigationLink(
+                                                value: NavigationDestination
+                                                    .certificateDetailView(certificate: signature.archiveTimestampCert)
+                                            ) {
+                                                SignerDetailView(
+                                                    signatureDataItem: SignatureDataItem(
+                                                        title: languageSettings.localized("Archive TS Certificate"),
+                                                        value: viewModel.getSubjectName(cert: signature.archiveTimestampCert),
+                                                        extraIcon: "ic_m3_expand_content_48pt_wght400",
+                                                    )
+                                                )
+                                            }
+                                            .buttonStyle(.plain)
+                                        }
                                     }
                                 }
                             })
diff --git a/RIADigiDoc/UI/Component/Container/Signing/IdCard/IdCardView.swift b/RIADigiDoc/UI/Component/Container/Signing/IdCard/IdCardView.swift
index 1156857f..7c572d15 100644
--- a/RIADigiDoc/UI/Component/Container/Signing/IdCard/IdCardView.swift
+++ b/RIADigiDoc/UI/Component/Container/Signing/IdCard/IdCardView.swift
@@ -121,6 +121,10 @@ struct IdCardView: View {
         languageSettings.localized("Signature added")
     }
 
+    private var extendingSignaturesFailedMessage: String {
+        languageSettings.localized("Extending signatures failed")
+    }
+
     private var generalErrorMessage: String {
         languageSettings.localized("General error")
     }
@@ -501,7 +505,11 @@ struct IdCardView: View {
             await MainActor.run {
                 idCardActionMessage = ""
 
-                showMessage(message: signatureAddedMessage, type: .success)
+                if viewModel.signatureExtensionFailed {
+                    showMessage(message: extendingSignaturesFailedMessage, type: .error)
+                } else {
+                    showMessage(message: signatureAddedMessage, type: .success)
+                }
 
                 onSuccess(container)
                 dismiss()
diff --git a/RIADigiDoc/UI/Component/Container/Signing/NFC/NFCView.swift b/RIADigiDoc/UI/Component/Container/Signing/NFC/NFCView.swift
index 80bf779a..bc42bc31 100644
--- a/RIADigiDoc/UI/Component/Container/Signing/NFC/NFCView.swift
+++ b/RIADigiDoc/UI/Component/Container/Signing/NFC/NFCView.swift
@@ -102,6 +102,10 @@ struct NFCView: View {
         languageSettings.localized("Signature added")
     }
 
+    private var extendingSignaturesFailedMessage: String {
+        languageSettings.localized("Extending signatures failed")
+    }
+
     let signedContainer: SignedContainerProtocol?
     let cryptoContainer: CryptoContainerProtocol?
 
@@ -371,10 +375,16 @@ struct NFCView: View {
                 return
             }
 
-            Toast.show(signatureAddedMessage, type: .success)
-
-            if voiceOverEnabled {
-                AccessibilityUtil.announceMessage(signatureAddedMessage)
+            if viewModel.signatureExtensionFailed {
+                Toast.show(extendingSignaturesFailedMessage, type: .error)
+                if voiceOverEnabled {
+                    AccessibilityUtil.announceMessage(extendingSignaturesFailedMessage)
+                }
+            } else {
+                Toast.show(signatureAddedMessage, type: .success)
+                if voiceOverEnabled {
+                    AccessibilityUtil.announceMessage(signatureAddedMessage)
+                }
             }
 
             onSuccess(container)
diff --git a/RIADigiDoc/UI/Component/Container/Signing/SignatureView.swift b/RIADigiDoc/UI/Component/Container/Signing/SignatureView.swift
index 73ad7e49..e0e20c19 100644
--- a/RIADigiDoc/UI/Component/Container/Signing/SignatureView.swift
+++ b/RIADigiDoc/UI/Component/Container/Signing/SignatureView.swift
@@ -42,6 +42,7 @@ struct SignatureView: View {
     let isTimestamp: Bool
     let nameUtil: NameUtilProtocol
     let signatureUtil: SignatureUtilProtocol
+    let certificateUtil: CertificateUtilProtocol
     let showSignedDate: Bool
     let showMoreOptionsButton: Bool
     let showRole: Bool
@@ -84,6 +85,7 @@ struct SignatureView: View {
         isTimestamp: Bool = false,
         nameUtil: NameUtilProtocol = Container.shared.nameUtil(),
         signatureUtil: SignatureUtilProtocol = Container.shared.signatureUtil(),
+        certificateUtil: CertificateUtilProtocol = Container.shared.certificateUtil(),
         showSignedDate: Bool = true,
         showMoreOptionsButton: Bool = true,
         showRole: Bool = true,
@@ -98,6 +100,7 @@ struct SignatureView: View {
         self.isTimestamp = isTimestamp
         self.nameUtil = nameUtil
         self.signatureUtil = signatureUtil
+        self.certificateUtil = certificateUtil
         self.showSignedDate = showSignedDate
         self.showMoreOptionsButton = showMoreOptionsButton
         self.showRole = showRole
@@ -106,6 +109,14 @@ struct SignatureView: View {
         self.onSelect = onSelect
     }
 
+    private var archiveTimestampInfo: (text: String, isExpired: Bool)? {
+        guard !isTimestamp && signature.isLTAExtended else { return nil }
+        guard let date = certificateUtil.getNotValidAfterDate(cert: signature.archiveTimestampCert) else { return nil }
+        let formatted = DateUtil.getFormattedDateTime(date: date, isUTC: false)
+        let text = languageSettings.localized("Archive timestamp valid until", [formatted.date])
+        return (text: text, isExpired: date < Date())
+    }
+
     var body: some View {
         let signedDate = DateUtil.getFormattedDateTime(
             dateTimeString: signature.trustedSigningTime,
@@ -147,7 +158,9 @@ struct SignatureView: View {
                         text: languageSettings.localized(
                             signatureUtil.getSignatureStatusText(status: signature.status)
                         ),
-                        status: signature.status
+                        status: signature.status,
+                        archiveTimestampText: archiveTimestampInfo?.text,
+                        isArchiveTimestampExpired: archiveTimestampInfo?.isExpired ?? false
                     )
                     .multilineTextAlignment(.center)
 
diff --git a/RIADigiDoc/UI/Component/Container/Signing/SigningView.swift b/RIADigiDoc/UI/Component/Container/Signing/SigningView.swift
index 806f8a53..87b58a47 100644
--- a/RIADigiDoc/UI/Component/Container/Signing/SigningView.swift
+++ b/RIADigiDoc/UI/Component/Container/Signing/SigningView.swift
@@ -48,6 +48,7 @@ struct SigningView: View {
     @State private var showRenameModal = false
     @State private var showRemoveSignatureModal = false
     @State private var showRemoveDataFileModal = false
+    @State private var showExtendSignaturesModal = false
     @State private var isImportingAddedFiles: Bool = false
 
     @State private var showingShareSheet = false
@@ -143,6 +144,16 @@ struct SigningView: View {
         viewModel.isNestedContainer()
     }
 
+    private var isExtendSignaturesButtonShown: Bool {
+        isSignedContainer && !isNestedContainer &&
+        !viewModel.isCadesContainer && !viewModel.isXadesContainer &&
+        viewModel.containerMimetype != Constants.MimeType.Ddoc
+    }
+
+    private var extendSignaturesLabel: String {
+        languageSettings.localized("Extend signatures")
+    }
+
     private var containerName: String {
         URL(fileURLWithPath: viewModel.containerName)
             .deletingPathExtension()
@@ -200,6 +211,7 @@ struct SigningView: View {
                                     isSaveButtonShown: true,
                                     isSignButtonShown: false,
                                     isEncryptButtonShown: !isContainerSigned && !isNestedContainer,
+                                    isExtendSignaturesButtonShown: isExtendSignaturesButtonShown,
                                     showLeftActionButton: isContainerSigned && isSignButtonShown,
                                     showRightActionButton: isContainerSigned && !isNestedContainer,
                                     leftActionButtonName: languageSettings.localized("Add signature"),
@@ -237,6 +249,9 @@ struct SigningView: View {
                                         Task {
                                             await convertToCryptoContainer()
                                         }
+                                    },
+                                    onExtendSignaturesClick: {
+                                        showExtendSignaturesModal = true
                                     }
                                 )
                                 .background(
@@ -458,9 +473,25 @@ struct SigningView: View {
                     onCancel: { showRemoveDataFileModal = false }
                 )
             }
+
+            if showExtendSignaturesModal {
+                ConfirmModalView(
+                    title: languageSettings.localized("Extend signatures"),
+                    message: languageSettings.localized("Extend signatures confirm message"),
+                    confirmButtonTitle: languageSettings.localized("Extend"),
+                    onConfirm: {
+                        showExtendSignaturesModal = false
+                        Task {
+                            await viewModel.extendSignatures()
+                        }
+                    },
+                    onCancel: { showExtendSignaturesModal = false }
+                )
+            }
         }
         .animation(.easeInOut, value: showRenameModal)
         .animation(.easeInOut, value: showRemoveSignatureModal)
+        .animation(.easeInOut, value: showExtendSignaturesModal)
         .onChange(of: viewModel.errorMessage) { _, error in
             guard let error else { return }
             let localizedMessage = languageSettings.localized(error.key, [error.args.joined(separator: ", ")])
@@ -481,6 +512,10 @@ struct SigningView: View {
                 AccessibilityUtil.announceMessage(localizedMessage)
             }
 
+            if message.key == "Signatures extended" {
+                selectedTab = .signatures
+            }
+
             viewModel.resetSuccessMessage()
         }
         .onChange(of: viewModel.navigateToNestedCryptoContainerView) { _, isNavigating in
diff --git a/RIADigiDoc/UI/Component/Shared/ColoredSignedStatusText.swift b/RIADigiDoc/UI/Component/Shared/ColoredSignedStatusText.swift
index 752cf75f..5066e8ed 100644
--- a/RIADigiDoc/UI/Component/Shared/ColoredSignedStatusText.swift
+++ b/RIADigiDoc/UI/Component/Shared/ColoredSignedStatusText.swift
@@ -26,6 +26,8 @@ struct ColoredSignedStatusText: View {
 
     let text: String
     let status: SignatureStatus
+    var archiveTimestampText: String? = nil
+    var isArchiveTimestampExpired: Bool = false
 
     private var isSignatureValidOrWarning: Bool {
         status == .valid || status == .warning || status == .nonQSCD
@@ -49,12 +51,20 @@ struct ColoredSignedStatusText: View {
     }
 
     var body: some View {
-        TagBadge(
-            text: text,
-            tagBackgroundColor: tagBackgroundColor,
-            tagContentColor: tagContentColor,
-            additionalTextColor: additionalTextColor
-        )
+        if let archiveText = archiveTimestampText {
+            TagBadge(
+                text: archiveText,
+                tagBackgroundColor: isArchiveTimestampExpired ? theme.errorContainer : theme.successContainer,
+                tagContentColor: isArchiveTimestampExpired ? theme.onErrorContainer : theme.onSuccessContainer
+            )
+        } else {
+            TagBadge(
+                text: text,
+                tagBackgroundColor: tagBackgroundColor,
+                tagContentColor: tagContentColor,
+                additionalTextColor: additionalTextColor
+            )
+        }
     }
 }
 
@@ -73,4 +83,10 @@ struct ColoredSignedStatusText: View {
         text: "Signature is unknown",
         status: .unknown
     )
+
+    ColoredSignedStatusText(
+        text: "Signature is valid",
+        status: .valid,
+        archiveTimestampText: "Archive timestamp"
+    )
 }
diff --git a/RIADigiDoc/UI/Component/Shared/TagBadge.swift b/RIADigiDoc/UI/Component/Shared/TagBadge.swift
index 20b8ff73..4a788b43 100644
--- a/RIADigiDoc/UI/Component/Shared/TagBadge.swift
+++ b/RIADigiDoc/UI/Component/Shared/TagBadge.swift
@@ -67,8 +67,9 @@ struct TagBadge: View {
                 Text(parts[0])
                     .font(typography.bodyMedium)
                     .lineLimit(nil)
-                    .multilineTextAlignment(.center)
+                    .multilineTextAlignment(.leading)
                     .fixedSize(horizontal: false, vertical: true)
+                    .frame(maxWidth: .infinity, alignment: .leading)
                     .padding(.horizontal, Dimensions.Padding.XSPadding)
                     .padding(.vertical, Dimensions.Padding.XXSPadding)
                     .background(tagBackgroundColor)
diff --git a/RIADigiDoc/UI/Component/SigningServicesSettingsView.swift b/RIADigiDoc/UI/Component/SigningServicesSettingsView.swift
index 1b5b5c42..70af197a 100644
--- a/RIADigiDoc/UI/Component/SigningServicesSettingsView.swift
+++ b/RIADigiDoc/UI/Component/SigningServicesSettingsView.swift
@@ -43,15 +43,19 @@ struct SigningServicesSettingsView: View {
                             selectedTab: $selectedTab,
                             titles: [
                                 languageSettings.localized("Main settings timestamp services title"),
-                                languageSettings.localized("Main settings mobile id and smart id title")
+                                languageSettings.localized("Main settings mobile id and smart id title"),
+                                languageSettings.localized("Main settings lta tab title")
                             ],
                             content: {
                                 if selectedTab == .timestampServices {
                                     TimeStampSettingsView()
                                         .padding(.horizontal, Dimensions.Padding.SPadding)
-                                } else {
+                                } else if selectedTab == .mobileIdAndSmartId {
                                     MobileIDSmartIDSettingsView()
                                         .padding(.horizontal, Dimensions.Padding.SPadding)
+                                } else {
+                                    LTASettingsView()
+                                        .padding(.horizontal, Dimensions.Padding.SPadding)
                                 }
                             }
                         )
diff --git a/RIADigiDoc/UI/Component/SigningServicesSettingsView/LTASettingsView.swift b/RIADigiDoc/UI/Component/SigningServicesSettingsView/LTASettingsView.swift
new file mode 100644
index 00000000..f70df2e6
--- /dev/null
+++ b/RIADigiDoc/UI/Component/SigningServicesSettingsView/LTASettingsView.swift
@@ -0,0 +1,70 @@
+/*
+ * Copyright 2017 - 2026 Riigi Infosüsteemi Amet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+import SwiftUI
+import FactoryKit
+
+struct LTASettingsView: View {
+    @Environment(LanguageSettings.self) private var languageSettings
+
+    @State private var viewModel: LTASettingsViewModel
+
+    init() {
+        _viewModel = State(wrappedValue: Container.shared.ltaSettingsViewModel())
+    }
+
+    var body: some View {
+        AdvancedSettingsSectionColumn(
+            title: languageSettings.localized("Main settings lta tab title"),
+            isScrollable: false
+        ) {
+            OutlinedRadioButtonCard(
+                title: languageSettings.localized("Main settings default lta disabled"),
+                isSelected: !viewModel.isDefaultLTAEnabled,
+                onSelect: {
+                    viewModel.isDefaultLTAEnabled = false
+                },
+                accessibilityInputLabel: .disabledSetting
+            )
+            OutlinedRadioButtonCard(
+                title: languageSettings.localized("Main settings default lta title"),
+                isSelected: viewModel.isDefaultLTAEnabled,
+                onSelect: {
+                    viewModel.isDefaultLTAEnabled = true
+                },
+                accessibilityInputLabel: .defaultSetting
+            )
+            Spacer()
+        }
+        .onDisappear {
+            Task {
+                await viewModel.saveSettings()
+            }
+        }
+    }
+}
+
+// MARK: - Preview
+
+#Preview {
+    LTASettingsView()
+        .environment(Container.shared.languageSettings())
+        .environment(Container.shared.themeSettings())
+        .environment(NavigationPathManager())
+}
diff --git a/RIADigiDoc/Util/Certificate/CertificateUtil.swift b/RIADigiDoc/Util/Certificate/CertificateUtil.swift
index e3d85bc2..2a8349ba 100644
--- a/RIADigiDoc/Util/Certificate/CertificateUtil.swift
+++ b/RIADigiDoc/Util/Certificate/CertificateUtil.swift
@@ -56,29 +56,30 @@ public struct CertificateUtil: CertificateUtilProtocol, Loggable {
     }
 
     public func getNotValidAfterWithExpiredLabel(cert: Data, expiredLabel: String) -> String {
-        do {
-            let certificate = try Certificate(derEncoded: cert.map { $0 })
-            let notValidAfterDate = certificate.notValidAfter
+        guard let notValidAfterDate = getNotValidAfterDate(cert: cert) else { return "" }
 
-            let dateTime = DateUtil.getFormattedDateTime(
-                date: notValidAfterDate,
-                isUTC: false
-            )
+        let dateTime = DateUtil.getFormattedDateTime(date: notValidAfterDate, isUTC: false)
 
-            let calendar = Calendar.current
-            let todayStart = calendar.startOfDay(for: Date())
-            let certStart = calendar.startOfDay(for: notValidAfterDate)
+        let calendar = Calendar.current
+        let todayStart = calendar.startOfDay(for: Date())
+        let certStart = calendar.startOfDay(for: notValidAfterDate)
 
-            if certStart < todayStart {
-                return "\(dateTime.date) (\(expiredLabel))"
-            } else {
-                return dateTime.date
-            }
+        if certStart < todayStart {
+            return "\(dateTime.date) (\(expiredLabel))"
+        } else {
+            return dateTime.date
+        }
+    }
+
+    public func getNotValidAfterDate(cert: Data) -> Date? {
+        do {
+            let certificate = try Certificate(derEncoded: cert.map { $0 })
+            return certificate.notValidAfter
         } catch {
             CertificateUtil.logger().error(
-                "Unable to get not valid after from certificate: \(String(reflecting: error))"
+                "Unable to get not valid after date from certificate: \(String(reflecting: error))"
             )
-            return ""
+            return nil
         }
     }
 
diff --git a/RIADigiDoc/Util/Certificate/CertificateUtilProtocol.swift b/RIADigiDoc/Util/Certificate/CertificateUtilProtocol.swift
index bc2ad737..ec430383 100644
--- a/RIADigiDoc/Util/Certificate/CertificateUtilProtocol.swift
+++ b/RIADigiDoc/Util/Certificate/CertificateUtilProtocol.swift
@@ -27,4 +27,5 @@ public protocol CertificateUtilProtocol: Sendable {
     func getSubjectAttribute(cert: Data, attribute: ASN1ObjectIdentifier) -> String
     func getNotValidAfterWithExpiredLabel(cert: Data, expiredLabel: String) -> String
     func getNotValidDate(_ certData: Data?) throws -> String?
+    func getNotValidAfterDate(cert: Data) -> Date?
 }
diff --git a/RIADigiDoc/ViewModel/LTASettingsViewModel.swift b/RIADigiDoc/ViewModel/LTASettingsViewModel.swift
new file mode 100644
index 00000000..2cbcf353
--- /dev/null
+++ b/RIADigiDoc/ViewModel/LTASettingsViewModel.swift
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2017 - 2026 Riigi Infosüsteemi Amet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+import Foundation
+
+@Observable
+@MainActor
+class LTASettingsViewModel: LTASettingsViewModelProtocol {
+
+    var isDefaultLTAEnabled: Bool = false
+
+    private let dataStore: DataStoreProtocol
+
+    init(dataStore: DataStoreProtocol) {
+        self.dataStore = dataStore
+        Task {
+            await loadSettings()
+        }
+    }
+
+    func loadSettings() async {
+        self.isDefaultLTAEnabled = await dataStore.getIsDefaultLTAEnabled()
+    }
+
+    func saveSettings() async {
+        await dataStore.setIsDefaultLTAEnabled(isDefaultLTAEnabled)
+    }
+}
diff --git a/RIADigiDoc/ViewModel/Protocols/LTASettingsViewModelProtocol.swift b/RIADigiDoc/ViewModel/Protocols/LTASettingsViewModelProtocol.swift
new file mode 100644
index 00000000..c2e9de35
--- /dev/null
+++ b/RIADigiDoc/ViewModel/Protocols/LTASettingsViewModelProtocol.swift
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2017 - 2026 Riigi Infosüsteemi Amet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+/// @mockable
+@MainActor
+public protocol LTASettingsViewModelProtocol: Sendable {
+    var isDefaultLTAEnabled: Bool { get }
+
+    func loadSettings() async
+    func saveSettings() async
+}
diff --git a/RIADigiDoc/ViewModel/Protocols/SigningViewModelProtocol.swift b/RIADigiDoc/ViewModel/Protocols/SigningViewModelProtocol.swift
index 9bbd858e..06182994 100644
--- a/RIADigiDoc/ViewModel/Protocols/SigningViewModelProtocol.swift
+++ b/RIADigiDoc/ViewModel/Protocols/SigningViewModelProtocol.swift
@@ -45,4 +45,5 @@ public protocol SigningViewModelProtocol: Sendable {
     func resetErrorMessage()
     func resetSuccessMessage()
     func convertToCryptoContainer() async -> Bool
+    func extendSignatures() async
 }
diff --git a/RIADigiDoc/ViewModel/Signing/IdCard/IdCardViewModel.swift b/RIADigiDoc/ViewModel/Signing/IdCard/IdCardViewModel.swift
index 6b037c37..071cbf34 100644
--- a/RIADigiDoc/ViewModel/Signing/IdCard/IdCardViewModel.swift
+++ b/RIADigiDoc/ViewModel/Signing/IdCard/IdCardViewModel.swift
@@ -37,6 +37,7 @@ class IdCardViewModel: IdCardViewModelProtocol, Loggable {
 
     var errorMessage: String?
     var errorExtraArguments: [String] = []
+    var signatureExtensionFailed = false
     var shouldDismissForError = false
     var showIdCardAlertMessage = false
     var idCardAlertMessageKey: String?
@@ -140,6 +141,7 @@ class IdCardViewModel: IdCardViewModelProtocol, Loggable {
         signedContainer: SignedContainerProtocol,
         roleData: RoleData
     ) async -> SignedContainerProtocol? {
+        signatureExtensionFailed = false
         do {
             let containerFile = await signedContainer.getRawContainerFile() ?? URL(fileURLWithPath: "")
             let pinSecureData = SecureData(Array(pin2.utf8))
@@ -183,10 +185,18 @@ class IdCardViewModel: IdCardViewModelProtocol, Loggable {
                 pin2: pinSecureData
             )
 
-            return try await signedContainer.addSignature(
+            let updatedContainer = try await signedContainer.addSignature(
                 signature: signatureData,
                 containerFile: containerFile
             )
+            let isLTAEnabled = await dataStore.getIsDefaultLTAEnabled()
+            do {
+                return try await updatedContainer.extendSignatureIfEnabled(isLTAEnabled)
+            } catch {
+                IdCardViewModel.logger().error("ID-CARD: Unable to extend signature: \(error)")
+                signatureExtensionFailed = true
+                return updatedContainer
+            }
         } catch {
             IdCardViewModel.logger().error(
                 "ID-CARD: Unable to read ID-card data to sign with ID-Card reader. \(error)"
diff --git a/RIADigiDoc/ViewModel/Signing/MobileId/MobileIdViewModel.swift b/RIADigiDoc/ViewModel/Signing/MobileId/MobileIdViewModel.swift
index 0cd05bed..4c8afc3a 100644
--- a/RIADigiDoc/ViewModel/Signing/MobileId/MobileIdViewModel.swift
+++ b/RIADigiDoc/ViewModel/Signing/MobileId/MobileIdViewModel.swift
@@ -239,8 +239,16 @@ class MobileIdViewModel: MobileIdViewModelProtocol, Loggable {
             )
 
             MobileIdViewModel.logger().info("Signature added successfully (Mobile-ID)")
-            mobileIdSuccessMessageKey = "Signature added"
-            return updatedContainer
+            let isLTAEnabled = await dataStore.getIsDefaultLTAEnabled()
+            do {
+                let extendedContainer = try await updatedContainer.extendSignatureIfEnabled(isLTAEnabled)
+                mobileIdSuccessMessageKey = "Signature added"
+                return extendedContainer
+            } catch {
+                MobileIdViewModel.logger().error("Unable to extend signature (Mobile-ID): \(error)")
+                mobileIdErrorMessageKey = "Extending signatures failed"
+                return updatedContainer
+            }
         } catch {
             MobileIdViewModel.logger().error("Unable to sign container with Mobile-ID: \(error)")
             handleSignatureAddingError(error)
diff --git a/RIADigiDoc/ViewModel/Signing/NFC/NFCViewModel.swift b/RIADigiDoc/ViewModel/Signing/NFC/NFCViewModel.swift
index eea8e433..1d68a428 100644
--- a/RIADigiDoc/ViewModel/Signing/NFC/NFCViewModel.swift
+++ b/RIADigiDoc/ViewModel/Signing/NFC/NFCViewModel.swift
@@ -44,6 +44,8 @@ class NFCViewModel: NFCViewModelProtocol, Loggable {
     var nfcAlertMessageExtraArguments: [String] = []
     var nfcAlertMessageUrl: String?
 
+    var signatureExtensionFailed = false
+
     private let nfcCANKeyFilename = Constants.File.nfcCANKey
 
     private let dataStore: DataStoreProtocol
@@ -379,6 +381,7 @@ class NFCViewModel: NFCViewModelProtocol, Loggable {
         strings: NFCSessionStrings
     ) async -> SignedContainerProtocol? {
         NFCViewModel.logger().info("NFC: Starting NFC signing")
+        signatureExtensionFailed = false
         let pin2Data = pin2.data(using: .utf8)
         guard let pin2Data else {
             NFCViewModel.logger().error("NFC: Failed to convert PIN2 to Data")
@@ -408,7 +411,14 @@ class NFCViewModel: NFCViewModelProtocol, Loggable {
                 strings: strings
             )
             NFCViewModel.logger().info("NFC: Signature added successfully")
-            return result
+            let isLTAEnabled = await dataStore.getIsDefaultLTAEnabled()
+            do {
+                return try await result.extendSignatureIfEnabled(isLTAEnabled)
+            } catch {
+                NFCViewModel.logger().error("NFC: Unable to extend signature: \(error)")
+                signatureExtensionFailed = true
+                return result
+            }
         } catch {
             NFCViewModel.logger().error("NFC: Signing operation failed")
 
diff --git a/RIADigiDoc/ViewModel/Signing/SmartId/SmartIdViewModel.swift b/RIADigiDoc/ViewModel/Signing/SmartId/SmartIdViewModel.swift
index b152c285..38ddbb7f 100644
--- a/RIADigiDoc/ViewModel/Signing/SmartId/SmartIdViewModel.swift
+++ b/RIADigiDoc/ViewModel/Signing/SmartId/SmartIdViewModel.swift
@@ -282,10 +282,18 @@ class SmartIdViewModel: SmartIdViewModelProtocol, Loggable {
             )
 
             SmartIdViewModel.logger().info("Signature added successfully (Smart-ID)")
-            smartIdSuccessMessageKey = "Signature added"
             notificationUtil.removeNotification(id: notificationIdentifier)
             await endLiveActivity()
-            return updatedContainer
+            let isLTAEnabled = await dataStore.getIsDefaultLTAEnabled()
+            do {
+                let extendedContainer = try await updatedContainer.extendSignatureIfEnabled(isLTAEnabled)
+                smartIdSuccessMessageKey = "Signature added"
+                return extendedContainer
+            } catch {
+                SmartIdViewModel.logger().error("Unable to extend signature (Smart-ID): \(error)")
+                smartIdErrorMessageKey = "Extending signatures failed"
+                return updatedContainer
+            }
         } catch {
             SmartIdViewModel.logger().error("Unable to sign container with Smart-ID: \(error)")
             handleSignatureAddingError(error)
diff --git a/RIADigiDoc/ViewModel/SigningViewModel.swift b/RIADigiDoc/ViewModel/SigningViewModel.swift
index 3096c174..2060e20f 100644
--- a/RIADigiDoc/ViewModel/SigningViewModel.swift
+++ b/RIADigiDoc/ViewModel/SigningViewModel.swift
@@ -582,6 +582,28 @@ class SigningViewModel: SigningViewModelProtocol, Loggable {
         successMessage = nil
     }
 
+    func extendSignatures() async {
+        guard let container = signedContainer else {
+            SigningViewModel.logger().error("Cannot extend signatures: container is nil")
+            errorMessage = ToastMessage(key: "Extending signatures failed", args: [])
+            return
+        }
+        let mimetype = await container.getContainerMimetype()
+        guard mimetype != Constants.MimeType.Ddoc else {
+            SigningViewModel.logger().error("Cannot extend signatures: DDOC containers are not supported")
+            errorMessage = ToastMessage(key: "Extending signatures failed", args: [])
+            return
+        }
+        do {
+            let extended = try await container.extendSignatures()
+            await loadContainerData(signedContainer: extended)
+            successMessage = ToastMessage(key: "Signatures extended", args: [])
+        } catch {
+            SigningViewModel.logger().error("Unable to extend signatures: \(error)")
+            errorMessage = ToastMessage(key: "Extending signatures failed", args: [])
+        }
+    }
+
     func convertToCryptoContainer() async -> Bool {
         do {
             guard let container = signedContainer else {
diff --git a/RIADigiDocTests/Util/Certificate/CertificateUtilTests.swift b/RIADigiDocTests/Util/Certificate/CertificateUtilTests.swift
index b993a655..3bcaa2aa 100644
--- a/RIADigiDocTests/Util/Certificate/CertificateUtilTests.swift
+++ b/RIADigiDocTests/Util/Certificate/CertificateUtilTests.swift
@@ -141,48 +141,6 @@ final class CertificateUtilTests {
         #expect(!notValidAfter.isEmpty)
     }
 
-    @Test
-    func getNotValidAfterWithExpiredLabel_successWithExpiredCert() {
-        let pemString = """
-            -----BEGIN CERTIFICATE-----
-            MIID0jCCArqgAwIBAgIBATANBgkqhkiG9w0BAQsFADCBgTELMAkGA1UEBhMCRUUx
-            EzARBgNVBAgMClRlc3QgU3RhdGUxEjAQBgNVBAcMCVRlc3QgQ2l0eTEaMBgGA1UE
-            CgwRVGVzdCBPcmdhbml6YXRpb24xEjAQBgNVBAsMCVRlc3QgVW5pdDEZMBcGA1UE
-            AwwQVGVzdCBDZXJ0aWZpY2F0ZTAeFw03MDAxMDEwMDAwMDBaFw03MDAxMDEyMzU5
-            NTlaMIGBMQswCQYDVQQGEwJFRTETMBEGA1UECAwKVGVzdCBTdGF0ZTESMBAGA1UE
-            BwwJVGVzdCBDaXR5MRowGAYDVQQKDBFUZXN0IE9yZ2FuaXphdGlvbjESMBAGA1UE
-            CwwJVGVzdCBVbml0MRkwFwYDVQQDDBBUZXN0IENlcnRpZmljYXRlMIIBIjANBgkq
-            hkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAp0tlBYafLZ4prdlTC+acvl+Z+p8oGxry
-            oRu3i/FIa8qAS/XHkL7DfmLdHkT3/N8Lclm1mQtVRtcmsMLbiPb6KiywlgZRWh4Z
-            JHS9t4WtcspxTjLjJ5DilmSPD1lepxCTq2VWECFPVSvh0Uo2Jr2WEWR0Az8MB0g6
-            2qfPz+ywNLKGjMMPOJEgEKpEylos/yU42qOja8r3Ocb2Bid7CbA8y3GzSZmIjS+X
-            GzmWqTe+4WaBTqAF3Wa5hhcVjbv9uYebgiF3puxYRGnqXR3wjxdH1Dt8VuP/cvic
-            ynDIEPltZbWIhLMkvIiJirtFQ2MWIJzyTgOg0EO1nFVzHBkn3OsUsQIDAQABo1Mw
-            UTAdBgNVHQ4EFgQUPcWKjZU/rXkRLqpssv/fUwpCkLAwHwYDVR0jBBgwFoAUPcWK
-            jZU/rXkRLqpssv/fUwpCkLAwDwYDVR0TAQH/BAUwAwEB/zANBgkqhkiG9w0BAQsF
-            AAOCAQEAQbAPahc6zJ37VxBN4xDn3xXShCxVF+3qMBw7YYJDU39NSnBfCjpCZUbG
-            QTZAXc3iMB6luO5yoBbUSjX0YT6hqwAyb5s/2Aucv5Y8nLIl/GOAYYCWpZrFVkD0
-            fmMt+rR6H5jFTtILsdsfMzmGkJ8xKWyjLUrGGALAzM1VSv1GPV+EpVjLe+bnTJ+E
-            mvPkvo7970DVF13AqjtE5929PJaMu4t7QHzUItdc74VOVkQ6OcC71nOWhPXlcVi2
-            AzZ3Zprwro1aLDmCQRSjBi1git9957oxuQfCtGvoeaP497hWZ4wJK/HRHLlGx1cu
-            HorK9eEA1jaJ/RRRefXzhjOVHLOuYw==
-            -----END CERTIFICATE-----
-            """
-        guard let pemData = pemString.data(using: .utf8) else {
-            Issue.record("Expected pemData to not be nil")
-            return
-        }
-        guard let derData = certificateUtil.pemToDerData(fromPEM: pemData) else {
-            Issue.record("Expected derData to not be nil")
-            return
-        }
-        let expiredLabel = "Expired"
-
-        let notValidAfter = certificateUtil.getNotValidAfterWithExpiredLabel(cert: derData, expiredLabel: expiredLabel)
-
-        #expect(notValidAfter.contains(expiredLabel))
-    }
-
     @Test
     func getSubjectAttribute_success() {
         let pemString = """
@@ -301,6 +259,103 @@ final class CertificateUtilTests {
         }
     }
 
+    @Test
+    func getNotValidAfterDate_returnsNonNilDateForValidCert() {
+        let pemString = """
+            -----BEGIN CERTIFICATE-----
+            MIIEDTCCAvWgAwIBAgIUSqorLsfSI1K5t/9YhPnHqf3MBc4wDQYJKoZIhvcNAQEL
+            BQAwgZUxCzAJBgNVBAYTAkVFMQ4wDAYDVQQIDAVIYXJqdTEQMA4GA1UEBwwHVGFs
+            bGlubjEOMAwGA1UECgwFTXlPcmcxDzANBgNVBAsMBk15VW5pdDESMBAGA1UEAwwJ
+            VGVzdCBDZXJ0MR8wHQYJKoZIhvcNAQkBFhB0ZXN0QGV4YW1wbGUuY29tMQ4wDAYD
+            VQQFEwUxMjM0NTAeFw0yNTEwMTYxMDMyMjJaFw0yNjEwMTYxMDMyMjJaMIGVMQsw
+            CQYDVQQGEwJFRTEOMAwGA1UECAwFSGFyanUxEDAOBgNVBAcMB1RhbGxpbm4xDjAM
+            BgNVBAoMBU15T3JnMQ8wDQYDVQQLDAZNeVVuaXQxEjAQBgNVBAMMCVRlc3QgQ2Vy
+            dDEfMB0GCSqGSIb3DQEJARYQdGVzdEBleGFtcGxlLmNvbTEOMAwGA1UEBRMFMTIz
+            NDUwggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQCWT6mHYaf1xuNus76z
+            MpVfk3HjI/ZxmswhbPG2LvAxldY7hXaCH8I0qMKorrnUqq3PmWZqG7Wzt78Lu5x8
+            SGCJ+fGKH4Fo3cXnGqXQpU1xnwARE08N/g3GlogDH3y0MsbUD/B7Vq218BrWqlEU
+            BiYI/aO7yfal4tZjVWugBalMWYehHhEOeh0ss4bDjGvEmmPAvRa36UoVbLGrjG95
+            vcZv2xCC8YlWyj11X4ci7RZHrbpNrZ21xWr59VU7dTxKIDJ64wfgddryXkiyPHJ3
+            R5Syf89qNn0I9SeEuSS13QsF0UEmcT/+rvXf2o8JXNWpPe2AGYVzlWAPHboOKHLI
+            2FILAgMBAAGjUzBRMB0GA1UdDgQWBBRLFCXwhwHQ2dmE3xocNJOtPB0DtzAfBgNV
+            HSMEGDAWgBRLFCXwhwHQ2dmE3xocNJOtPB0DtzAPBgNVHRMBAf8EBTADAQH/MA0G
+            CSqGSIb3DQEBCwUAA4IBAQB53+FGg8nzYBIq8K/C00GUB2R0XYxUvKsfvecMOcHy
+            Sl7TKOVZRDaL7Ji3G5CqouAwLFgnXqlf7aKYn4YfWNNXoS9Zm+eFJmvvWYJ/j/C0
+            Ntz2mfcMcElrXvCGVnCNiHmkAw193jnya+3JxgbgE8rHoxYMHGwNTZUzCe7QGqw/
+            tLdAYRezgyOx5NqaCq1GsOIP3n3eU9k92bMaWM0qtYHroL3H+oIvO0Whdsi2H7Fz
+            W+L77xnqmKNZDyWwyQ8MsShy8VAJt75TOLPrR6clKou1q3H77ELDtwUAHw7hJF7W
+            HERHoea8LiuAkZCFBh6fTEd2Wetgble1vYsK/+t+0Y4J
+            -----END CERTIFICATE-----
+            """
+        guard let pemData = pemString.data(using: .utf8),
+              let derData = certificateUtil.pemToDerData(fromPEM: pemData) else {
+            Issue.record("Expected derData to not be nil")
+            return
+        }
+
+        let result = certificateUtil.getNotValidAfterDate(cert: derData)
+
+        #expect(result != nil)
+    }
+
+    @Test
+    func getNotValidAfterDate_returnsExpiredDateForExpiredCert() {
+        let pemString = """
+            -----BEGIN CERTIFICATE-----
+            MIID0jCCArqgAwIBAgIBATANBgkqhkiG9w0BAQsFADCBgTELMAkGA1UEBhMCRUUx
+            EzARBgNVBAgMClRlc3QgU3RhdGUxEjAQBgNVBAcMCVRlc3QgQ2l0eTEaMBgGA1UE
+            CgwRVGVzdCBPcmdhbml6YXRpb24xEjAQBgNVBAsMCVRlc3QgVW5pdDEZMBcGA1UE
+            AwwQVGVzdCBDZXJ0aWZpY2F0ZTAeFw03MDAxMDEwMDAwMDBaFw03MDAxMDEyMzU5
+            NTlaMIGBMQswCQYDVQQGEwJFRTETMBEGA1UECAwKVGVzdCBTdGF0ZTESMBAGA1UE
+            BwwJVGVzdCBDaXR5MRowGAYDVQQKDBFUZXN0IE9yZ2FuaXphdGlvbjESMBAGA1UE
+            CwwJVGVzdCBVbml0MRkwFwYDVQQDDBBUZXN0IENlcnRpZmljYXRlMIIBIjANBgkq
+            hkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAp0tlBYafLZ4prdlTC+acvl+Z+p8oGxry
+            oRu3i/FIa8qAS/XHkL7DfmLdHkT3/N8Lclm1mQtVRtcmsMLbiPb6KiywlgZRWh4Z
+            JHS9t4WtcspxTjLjJ5DilmSPD1lepxCTq2VWECFPVSvh0Uo2Jr2WEWR0Az8MB0g6
+            2qfPz+ywNLKGjMMPOJEgEKpEylos/yU42qOja8r3Ocb2Bid7CbA8y3GzSZmIjS+X
+            GzmWqTe+4WaBTqAF3Wa5hhcVjbv9uYebgiF3puxYRGnqXR3wjxdH1Dt8VuP/cvic
+            ynDIEPltZbWIhLMkvIiJirtFQ2MWIJzyTgOg0EO1nFVzHBkn3OsUsQIDAQABo1Mw
+            UTAdBgNVHQ4EFgQUPcWKjZU/rXkRLqpssv/fUwpCkLAwHwYDVR0jBBgwFoAUPcWK
+            jZU/rXkRLqpssv/fUwpCkLAwDwYDVR0TAQH/BAUwAwEB/zANBgkqhkiG9w0BAQsF
+            AAOCAQEAQbAPahc6zJ37VxBN4xDn3xXShCxVF+3qMBw7YYJDU39NSnBfCjpCZUbG
+            QTZAXc3iMB6luO5yoBbUSjX0YT6hqwAyb5s/2Aucv5Y8nLIl/GOAYYCWpZrFVkD0
+            fmMt+rR6H5jFTtILsdsfMzmGkJ8xKWyjLUrGGALAzM1VSv1GPV+EpVjLe+bnTJ+E
+            mvPkvo7970DVF13AqjtE5929PJaMu4t7QHzUItdc74VOVkQ6OcC71nOWhPXlcVi2
+            AzZ3Zprwro1aLDmCQRSjBi1git9957oxuQfCtGvoeaP497hWZ4wJK/HRHLlGx1cu
+            HorK9eEA1jaJ/RRRefXzhjOVHLOuYw==
+            -----END CERTIFICATE-----
+            """
+        guard let pemData = pemString.data(using: .utf8),
+              let derData = certificateUtil.pemToDerData(fromPEM: pemData) else {
+            Issue.record("Expected derData to not be nil")
+            return
+        }
+
+        let result = certificateUtil.getNotValidAfterDate(cert: derData)
+
+        guard let date = result else {
+            Issue.record("Expected date to not be nil")
+            return
+        }
+        #expect(date < Date())
+    }
+
+    @Test
+    func getNotValidAfterDate_returnsNilOnInvalidDer() {
+        let invalidDer = Data([0x00, 0x01, 0x02])
+
+        let result = certificateUtil.getNotValidAfterDate(cert: invalidDer)
+
+        #expect(result == nil)
+    }
+
+    @Test
+    func getNotValidAfterDate_returnsNilOnEmptyData() {
+        let result = certificateUtil.getNotValidAfterDate(cert: Data())
+
+        #expect(result == nil)
+    }
+
     @Test
     func getNotValidDate_success() throws {
         let pemString = """
diff --git a/RIADigiDocTests/ViewModel/LTASettingsViewModelTests.swift b/RIADigiDocTests/ViewModel/LTASettingsViewModelTests.swift
new file mode 100644
index 00000000..75074a0f
--- /dev/null
+++ b/RIADigiDocTests/ViewModel/LTASettingsViewModelTests.swift
@@ -0,0 +1,81 @@
+/*
+ * Copyright 2017 - 2026 Riigi Infosüsteemi Amet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+import Foundation
+import Testing
+
+@MainActor
+final class LTASettingsViewModelTests {
+
+    private let mockDataStore: DataStoreProtocolMock
+
+    init() {
+        mockDataStore = DataStoreProtocolMock()
+        mockDataStore.getIsDefaultLTAEnabledHandler = { false }
+    }
+
+    @Test
+    func isDefaultLTAEnabled_defaultsToFalse() async {
+        let viewModel = LTASettingsViewModel(dataStore: mockDataStore)
+
+        #expect(!viewModel.isDefaultLTAEnabled)
+    }
+
+    @Test
+    func loadSettings_setsIsDefaultLTAEnabledToTrue() async {
+        mockDataStore.getIsDefaultLTAEnabledHandler = { true }
+        let viewModel = LTASettingsViewModel(dataStore: mockDataStore)
+
+        await viewModel.loadSettings()
+
+        #expect(viewModel.isDefaultLTAEnabled)
+    }
+
+    @Test
+    func loadSettings_setsIsDefaultLTAEnabledToFalse() async {
+        mockDataStore.getIsDefaultLTAEnabledHandler = { false }
+        let viewModel = LTASettingsViewModel(dataStore: mockDataStore)
+
+        await viewModel.loadSettings()
+
+        #expect(!viewModel.isDefaultLTAEnabled)
+    }
+
+    @Test
+    func saveSettings_savesEnabledStateToDataStore() async {
+        let viewModel = LTASettingsViewModel(dataStore: mockDataStore)
+        viewModel.isDefaultLTAEnabled = true
+
+        await viewModel.saveSettings()
+
+        #expect(mockDataStore.setIsDefaultLTAEnabledCallCount == 1)
+        #expect(mockDataStore.setIsDefaultLTAEnabledArgValues.first == true)
+    }
+
+    @Test
+    func saveSettings_savesDisabledStateToDataStore() async {
+        let viewModel = LTASettingsViewModel(dataStore: mockDataStore)
+        viewModel.isDefaultLTAEnabled = false
+
+        await viewModel.saveSettings()
+
+        #expect(mockDataStore.setIsDefaultLTAEnabledCallCount == 1)
+        #expect(mockDataStore.setIsDefaultLTAEnabledArgValues.first == false)
+    }
+}
diff --git a/RIADigiDocTests/ViewModel/SigningViewModelTests.swift b/RIADigiDocTests/ViewModel/SigningViewModelTests.swift
index c6a2de2b..619895b0 100644
--- a/RIADigiDocTests/ViewModel/SigningViewModelTests.swift
+++ b/RIADigiDocTests/ViewModel/SigningViewModelTests.swift
@@ -1472,6 +1472,74 @@ struct SigningViewModelTests: Loggable {
         #expect(viewModel.dataFiles.count == 2)
     }
 
+    @Test
+    func extendSignatures_setsSuccessMessageWhenExtensionSucceeds() async {
+        let mockSignedContainer = SignedContainerProtocolMock()
+        mockSignedContainer.getContainerMimetypeHandler = { Constants.MimeType.Asice }
+        mockSignedContainer.extendSignaturesHandler = { mockSignedContainer }
+        mockSignedContainer.getDataFilesHandler = { [] }
+        mockSignedContainer.getSignaturesHandler = { [] }
+
+        await viewModel.loadContainerData(signedContainer: mockSignedContainer)
+        await viewModel.extendSignatures()
+
+        #expect(viewModel.successMessage == ToastMessage(key: "Signatures extended", args: []))
+        #expect(viewModel.errorMessage == nil)
+    }
+
+    @Test
+    func extendSignatures_setsErrorMessageWhenContainerIsNil() async {
+        await viewModel.extendSignatures()
+
+        #expect(viewModel.errorMessage == ToastMessage(key: "Extending signatures failed", args: []))
+        #expect(viewModel.successMessage == nil)
+    }
+
+    @Test
+    func extendSignatures_setsErrorMessageWhenContainerIsDdoc() async {
+        let mockSignedContainer = SignedContainerProtocolMock()
+        mockSignedContainer.getContainerMimetypeHandler = { Constants.MimeType.Ddoc }
+
+        await viewModel.loadContainerData(signedContainer: mockSignedContainer)
+        await viewModel.extendSignatures()
+
+        #expect(viewModel.errorMessage == ToastMessage(key: "Extending signatures failed", args: []))
+        #expect(viewModel.successMessage == nil)
+        #expect(mockSignedContainer.extendSignaturesCallCount == 0)
+    }
+
+    @Test
+    func extendSignatures_setsErrorMessageWhenExtensionThrows() async {
+        let mockSignedContainer = SignedContainerProtocolMock()
+        mockSignedContainer.getContainerMimetypeHandler = { Constants.MimeType.Asice }
+        mockSignedContainer.extendSignaturesHandler = {
+            throw DigiDocError.signatureExtensionFailed(ErrorDetail(message: "Extension failed"))
+        }
+
+        await viewModel.loadContainerData(signedContainer: mockSignedContainer)
+        await viewModel.extendSignatures()
+
+        #expect(viewModel.errorMessage == ToastMessage(key: "Extending signatures failed", args: []))
+        #expect(viewModel.successMessage == nil)
+    }
+
+    @Test
+    func extendSignatures_loadsContainerDataAfterSuccessfulExtension() async {
+        let extendedContainer = SignedContainerProtocolMock()
+        let signature = MockSignatureWrapper.mockSignatureWrapper(signatureId: "S-extended")
+        extendedContainer.getDataFilesHandler = { [] }
+        extendedContainer.getSignaturesHandler = { [signature] }
+
+        let mockSignedContainer = SignedContainerProtocolMock()
+        mockSignedContainer.getContainerMimetypeHandler = { Constants.MimeType.Asice }
+        mockSignedContainer.extendSignaturesHandler = { extendedContainer }
+
+        await viewModel.loadContainerData(signedContainer: mockSignedContainer)
+        await viewModel.extendSignatures()
+
+        #expect(viewModel.signatures.first?.signatureId == "S-extended")
+    }
+
     @Test
     func convertToCryptoContainer_successWithExistingContainer() async throws {
         let mockSignedContainer = SignedContainerProtocolMock()