element-hq/element-ios/issues/4255 - Added fallback keys to the dehyd…

…rated device. Removed unused dehydration key.
matrix-org · Sep 17, 2021 · 596370e · 596370e
1 parent 175c34c
commit 596370e
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Showing 4 changed files with 51 additions and 25 deletions.
diff --git a/MatrixSDK/Crypto/Dehydration/MXDehydrationService.h b/MatrixSDK/Crypto/Dehydration/MXDehydrationService.h
@@ -22,9 +22,6 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-/// MXKeyProvider identifier for a 32 bytes long key used to pickle / unpickle the account of the dehydrated device.
-FOUNDATION_EXPORT NSString *const MXDehydrationServiceKeyDataType;
-
 /// Error domain for this class.
 FOUNDATION_EXPORT NSString *const MXDehydrationServiceErrorDomain;
 

diff --git a/MatrixSDK/Crypto/Dehydration/MXDehydrationService.m b/MatrixSDK/Crypto/Dehydration/MXDehydrationService.m
@@ -26,7 +26,6 @@
 #import "MXKey.h"
 
 NSString *const MXDehydrationAlgorithm = @"org.matrix.msc2697.v1.olm.libolm_pickle";
-NSString *const MXDehydrationServiceKeyDataType = @"org.matrix.sdk.dehydration.service.key";
 NSString *const MXDehydrationServiceErrorDomain = @"org.matrix.sdk.dehydration.service";
 
 @interface MXDehydrationService ()
@@ -62,8 +61,8 @@ - (void)dehydrateDeviceWithMatrixRestClient:(MXRestClient*)restClient
 
     NSUInteger maxKeys = [account maxOneTimeKeys];
     [account generateOneTimeKeys:maxKeys / 2];
-
-    // TODO: [account generateFallbackKey];
+    
+    [account generateFallbackKey];
 
     MXLogDebug(@"[MXDehydrationService] dehydrateDevice: Account created %@", account.identityKeys);
 
@@ -210,27 +209,20 @@ - (void)uploadDeviceInfo:(MXDeviceInfo*)deviceInfo
 {
     MXLogDebug(@"[MXDehydrationService] uploadDeviceInfo: preparing one time keys");
 
-    NSDictionary *oneTimeKeys = account.oneTimeKeys;
-    NSMutableDictionary *oneTimeJson = [NSMutableDictionary dictionary];
+    NSDictionary *oneTimeKeys = [self signKeys:account.oneTimeKeys
+                                   withAccount:account
+                                        userId:restClient.credentials.userId
+                                      deviceId:deviceInfo.deviceId];
 
-    for (NSString *keyId in oneTimeKeys[kMXKeyCurve25519Type])
-    {
-        // Sign each one-time key
-        NSMutableDictionary *key = [NSMutableDictionary dictionary];
-        key[@"key"] = oneTimeKeys[kMXKeyCurve25519Type][keyId];
-
-        NSString *signature = [account signMessage:[MXCryptoTools canonicalJSONDataForJSON:key]];
-        key[@"signatures"] = @{
-            restClient.credentials.userId: @{
-                    [NSString stringWithFormat:@"%@:%@", kMXKeyEd25519Type, deviceInfo.deviceId]: signature
-            }
-        };
-
-        oneTimeJson[[NSString stringWithFormat:@"signed_curve25519:%@", keyId]] = key;
-    }
+    MXLogDebug(@"[MXDehydrationService] uploadDeviceInfo: preparing fallback keys");
+
+    NSDictionary *fallbackKeys = [self signKeys:account.fallbackKey
+                                    withAccount:account
+                                         userId:restClient.credentials.userId
+                                       deviceId:deviceInfo.deviceId];
 
     MXWeakify(self);
-    [restClient uploadKeys:deviceInfo.JSONDictionary oneTimeKeys:oneTimeJson fallbackKeys:nil forDeviceWithId:deviceInfo.deviceId success:^(MXKeysUploadResponse *keysUploadResponse) {
+    [restClient uploadKeys:deviceInfo.JSONDictionary oneTimeKeys:oneTimeKeys fallbackKeys:fallbackKeys forDeviceWithId:deviceInfo.deviceId success:^(MXKeysUploadResponse *keysUploadResponse) {
         [account markOneTimeKeysAsPublished];
         MXLogDebug(@"[MXDehydrationService] uploadDeviceInfo: dehydration done successfully with device ID: %@ ed25519: %@ curve25519: %@", deviceInfo.deviceId, account.identityKeys[kMXKeyEd25519Type], account.identityKeys[kMXKeyCurve25519Type]);
         MXStrongifyAndReturnIfNil(self);
@@ -251,4 +243,30 @@ - (void)stopProgress
     self.inProgress = NO;
 }
 
+- (NSDictionary *)signKeys:(NSDictionary *)keys
+               withAccount:(OLMAccount *)account
+                    userId:(NSString *)userId
+                  deviceId:(NSString *)deviceId
+
+{
+    NSMutableDictionary *signedKeys = [NSMutableDictionary dictionary];
+
+    for (NSString *keyId in keys[kMXKeyCurve25519Type])
+    {
+        NSMutableDictionary *key = [NSMutableDictionary dictionary];
+        key[@"key"] = keys[kMXKeyCurve25519Type][keyId];
+
+        NSString *signature = [account signMessage:[MXCryptoTools canonicalJSONDataForJSON:key]];
+        key[@"signatures"] = @{
+            userId: @{
+                    [NSString stringWithFormat:@"%@:%@", kMXKeyEd25519Type, deviceId]: signature
+            }
+        };
+
+        signedKeys[[NSString stringWithFormat:@"%@:%@", kMXKeySignedCurve25519Type, keyId]] = key;
+    }
+
+    return signedKeys;
+}
+
 @end
diff --git a/MatrixSDKTests/MXDehydrationTests.m b/MatrixSDKTests/MXDehydrationTests.m
@@ -463,6 +463,12 @@ -(void)testDataPickling
     OLMAccount *account = [[OLMAccount alloc] initNewAccount];
     NSDictionary *e2eKeys = [account identityKeys];
 
+    [account generateOneTimeKeys:50];
+    NSDictionary *oneTimeKeys = [account oneTimeKeys];
+
+    [account generateFallbackKey];
+    NSDictionary *fallbackKey = [account fallbackKey];
+
     // - pickle the OLM account
     NSData *key = [@"6fXK17pQFUrFqOnxt3wrqz8RHkQUT9vQ" dataUsingEncoding:NSUTF8StringEncoding];
     NSError *error = nil;
@@ -473,11 +479,16 @@ -(void)testDataPickling
     // - unpickle the pickled account
     OLMAccount *deserializedAccount = [[OLMAccount alloc] initWithSerializedData:serializedAccount key:key error:&error];
     NSDictionary *deserializedE2eKeys = [deserializedAccount identityKeys];
+    NSDictionary *deserializedOneTimeKeys = [deserializedAccount oneTimeKeys];
+    NSDictionary *deserializedFallbackKey = [deserializedAccount fallbackKey];
 
     // -> identity keys must be the same
     XCTAssertNil(error, "initWithSerializedData failed due to error %@", error);
     XCTAssert([e2eKeys[@"ed25519"] isEqual:deserializedE2eKeys[@"ed25519"]], @"wrong deserialized ed25519 key %@ != %@", e2eKeys[@"ed25519"], deserializedE2eKeys[@"ed25519"]);
     XCTAssert([e2eKeys[@"curve25519"] isEqual:deserializedE2eKeys[@"curve25519"]], @"wrong deserialized curve25519 key %@ != %@", e2eKeys[@"curve25519"], deserializedE2eKeys[@"curve25519"]);
+
+    XCTAssert([oneTimeKeys isEqualToDictionary:deserializedOneTimeKeys]);
+    XCTAssert([fallbackKey isEqualToDictionary:deserializedFallbackKey]);
 }
 
 #pragma mark - Private methods

diff --git a/changelog.d/4255.change b/changelog.d/4255.change
@@ -1 +1 @@
-Sign dehydrated device info with the MSK.
+Add fallback keys to the dehydrated device info and sign it with the MSK.
Original file line number	Diff line number	Diff line change
		@@ -1 +1 @@
		Sign dehydrated device info with the MSK.
		Add fallback keys to the dehydrated device info and sign it with the MSK.