Update README.md

Don't archive sessions when they are fresh.
Increase ratchet counter limit
2021-04-08 10:21:14 -07:00 · 2021-01-16 18:04:32 -08:00 · 2021-01-16 12:49:24 -08:00 · 2020-11-12 17:45:51 -08:00 · 2020-11-12 17:27:02 -08:00 · 2020-11-12 17:26:50 -08:00
28 changed files with 290 additions and 194 deletions
--- a/AxolotlKit.podspec
+++ b/AxolotlKit.podspec
@ -11,7 +11,7 @@ Pod::Spec.new do |s|
  s.source_files          = "AxolotlKit/Classes/**/*.{h,m,swift}", "AxolotlKit/Private/*.{h,m,swift}"
  s.public_header_files   = "AxolotlKit/Classes/**/*.{h}"
  s.prefix_header_file    = "AxolotlKit/SPKPrefix.h"
-  s.ios.deployment_target = "9.0"
+  s.ios.deployment_target = "10.0"
  s.osx.deployment_target = "10.8"
  s.requires_arc          = true
  
--- a/AxolotlKit.xcodeproj/project.pbxproj
+++ b/AxolotlKit.xcodeproj/project.pbxproj
@ -310,6 +310,7 @@
 			developmentRegion = English;
 			hasScannedForEncodings = 0;
 			knownRegions = (
+				English,
 				en,
 			);
 			mainGroup = B6B98F6F197D838A00B16B5E;
@ -526,7 +527,7 @@
 					"$(inherited)",
 				);
 				INFOPLIST_FILE = "AxolotlKit/AxolotlKit-Info.plist";
-				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 10.0;
 				PRODUCT_BUNDLE_IDENTIFIER = org.whispersystems.SignalProtocolKitTestApp;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				WRAPPER_EXTENSION = app;
@ -543,7 +544,7 @@
 				GCC_PRECOMPILE_PREFIX_HEADER = YES;
 				GCC_PREFIX_HEADER = "";
 				INFOPLIST_FILE = "AxolotlKit/AxolotlKit-Info.plist";
-				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 10.0;
 				PRODUCT_BUNDLE_IDENTIFIER = org.whispersystems.SignalProtocolKitTestApp;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				WRAPPER_EXTENSION = app;
@ -639,7 +640,7 @@
 					"$(inherited)",
 					/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include,
 				);
-				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 10.0;
 				MTL_ENABLE_DEBUG_INFO = YES;
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = iphoneos;
@ -685,7 +686,7 @@
 					"$(inherited)",
 					/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include,
 				);
-				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 10.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				TARGETED_DEVICE_FAMILY = "1,2";
--- a/AxolotlKit/Classes/Prekeys/PreKeyBundle.h
+++ b/AxolotlKit/Classes/Prekeys/PreKeyBundle.h
@ -1,13 +1,11 @@
 //
-//  AxolotlKeyFetch.h
-//  AxolotlKit
-//
-//  Created by Frederic Jacobs on 21/07/14.
-//  Copyright (c) 2014 Frederic Jacobs. All rights reserved.
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
 //

 #import <Foundation/Foundation.h>

+NS_ASSUME_NONNULL_BEGIN
+
@interface PreKeyBundle : NSObject <NSSecureCoding>

@property (nonatomic, readonly) NSData   *identityKey;
@ -29,3 +27,5 @@
                                    identityKey:(NSData *)identityKey;

@end
+
+NS_ASSUME_NONNULL_END
--- a/AxolotlKit/Classes/Prekeys/PreKeyBundle.m
+++ b/AxolotlKit/Classes/Prekeys/PreKeyBundle.m
@ -1,13 +1,10 @@
 //
-//  AxolotlKeyFetch.m
-//  AxolotlKit
-//
-//  Created by Frederic Jacobs on 21/07/14.
-//  Copyright (c) 2014 Frederic Jacobs. All rights reserved.
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
 //

 #import "PreKeyBundle.h"

+NS_ASSUME_NONNULL_BEGIN

 static NSString* const kCoderPKBIdentityKey           = @"kCoderPKBIdentityKey";
 static NSString* const kCoderPKBregistrationId        = @"kCoderPKBregistrationId";
@ -62,7 +59,8 @@ static NSString* const kCoderPKBsignedPreKeySignature = @"kCoderPKBsignedPreKeyS
    return self;
 }

- (id)initWithCoder:(NSCoder *)aDecoder{
+- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder
+{
    int registrationId            = [aDecoder decodeIntForKey:kCoderPKBregistrationId];
    int deviceId                  = [aDecoder decodeIntForKey:kCoderPKBdeviceId];
    int preKeyId                  = [aDecoder decodeIntForKey:kCoderPKBpreKeyId];
@ -103,3 +101,5 @@ static NSString* const kCoderPKBsignedPreKeySignature = @"kCoderPKBsignedPreKeyS
 }

@end
+
+NS_ASSUME_NONNULL_END
--- a/AxolotlKit/Classes/Prekeys/PreKeyRecord.h
+++ b/AxolotlKit/Classes/Prekeys/PreKeyRecord.h
@ -5,12 +5,20 @@
 #import <Curve25519Kit/Curve25519.h>
 #import <Foundation/Foundation.h>

+NS_ASSUME_NONNULL_BEGIN

@interface PreKeyRecord : NSObject <NSSecureCoding>

@property (nonatomic, readonly) int       Id;
@property (nonatomic, readonly) ECKeyPair *keyPair;
+@property (nonatomic, readonly, nullable) NSDate *createdAt;

- (instancetype)initWithId:(int)identifier keyPair:(ECKeyPair*)keyPair;
+- (instancetype)initWithId:(int)identifier
+                   keyPair:(ECKeyPair *)keyPair
+                 createdAt:(NSDate *)createdAt;
+
+- (void)setCreatedAtToNow;

@end
+
+NS_ASSUME_NONNULL_END
--- a/AxolotlKit/Classes/Prekeys/PreKeyRecord.m
+++ b/AxolotlKit/Classes/Prekeys/PreKeyRecord.m
@ -8,8 +8,11 @@

 #import "PreKeyRecord.h"

+NS_ASSUME_NONNULL_BEGIN
+
 static NSString* const kCoderPreKeyId        = @"kCoderPreKeyId";
 static NSString* const kCoderPreKeyPair      = @"kCoderPreKeyPair";
+static NSString* const kCoderCreatedAt       = @"kCoderCreatedAt";

@implementation PreKeyRecord

@ -17,7 +20,10 @@ static NSString* const kCoderPreKeyPair      = @"kCoderPreKeyPair";
    return YES;
 }

- (instancetype)initWithId:(int)identifier keyPair:(ECKeyPair*)keyPair{
+- (instancetype)initWithId:(int)identifier
+                   keyPair:(ECKeyPair*)keyPair
+                 createdAt:(NSDate *)createdAt
+{
    OWSAssert(keyPair);

    self = [super init];
@ -25,20 +31,30 @@ static NSString* const kCoderPreKeyPair      = @"kCoderPreKeyPair";
    if (self) {
        _Id      = identifier;
        _keyPair = keyPair;
+        _createdAt = createdAt;
    }
    
    return self;
 }

- (id)initWithCoder:(NSCoder *)aDecoder{
-    return [self initWithId:[aDecoder decodeIntForKey:kCoderPreKeyId] keyPair:[aDecoder decodeObjectOfClass:[ECKeyPair class] forKey:kCoderPreKeyPair]];
+- (nullable id)initWithCoder:(NSCoder *)aDecoder {
+    return [self initWithId:[aDecoder decodeIntForKey:kCoderPreKeyId]
+                    keyPair:[aDecoder decodeObjectOfClass:[ECKeyPair class] forKey:kCoderPreKeyPair]
+                  createdAt:[aDecoder decodeObjectOfClass:[NSDate class] forKey:kCoderCreatedAt]];
 }

 - (void)encodeWithCoder:(NSCoder *)aCoder{
    [aCoder encodeInteger:_Id forKey:kCoderPreKeyId];
    [aCoder encodeObject:_keyPair forKey:kCoderPreKeyPair];
+    if (_createdAt != nil) {
+        [aCoder encodeObject:_createdAt forKey:kCoderCreatedAt];
+    }
 }

-
+- (void)setCreatedAtToNow {
+    _createdAt = [NSDate date];
+}

@end
+
+NS_ASSUME_NONNULL_END
--- a/AxolotlKit/Classes/Prekeys/SignedPrekeyRecord.h
+++ b/AxolotlKit/Classes/Prekeys/SignedPrekeyRecord.h
@ -6,6 +6,8 @@
 #import "PreKeyRecord.h"
 #import <Curve25519Kit/Curve25519.h>

+NS_ASSUME_NONNULL_BEGIN
+
@interface SignedPreKeyRecord : PreKeyRecord <NSSecureCoding>

@property (nonatomic, readonly) NSData *signature;
@ -19,3 +21,5 @@
 - (void)markAsAcceptedByService;

@end
+
+NS_ASSUME_NONNULL_END
--- a/AxolotlKit/Classes/Prekeys/SignedPrekeyRecord.m
+++ b/AxolotlKit/Classes/Prekeys/SignedPrekeyRecord.m
@ -4,6 +4,8 @@

 #import "SignedPrekeyRecord.h"

+NS_ASSUME_NONNULL_BEGIN
+
 static NSString* const kCoderPreKeyId        = @"kCoderPreKeyId";
 static NSString* const kCoderPreKeyPair      = @"kCoderPreKeyPair";
 static NSString* const kCoderPreKeyDate      = @"kCoderPreKeyDate";
@ -26,7 +28,9 @@ static NSString *const kCoderPreKeyWasAcceptedByService = @"kCoderPreKeyWasAccep
    OWSAssert(signature);
    OWSAssert(generatedAt);

-    self = [super initWithId:identifier keyPair:keyPair];
+    self = [super initWithId:identifier
+                     keyPair:keyPair
+                   createdAt:generatedAt];

    if (self) {
        _signature = signature;
@ -38,7 +42,9 @@ static NSString *const kCoderPreKeyWasAcceptedByService = @"kCoderPreKeyWasAccep
 }

 - (instancetype)initWithId:(int)identifier keyPair:(ECKeyPair *)keyPair signature:(NSData*)signature generatedAt:(NSDate *)generatedAt{
-    self = [super initWithId:identifier keyPair:keyPair];
+    self = [super initWithId:identifier
+                     keyPair:keyPair
+                   createdAt:generatedAt];
    
    if (self) {
        _signature = signature;
@ -48,7 +54,7 @@ static NSString *const kCoderPreKeyWasAcceptedByService = @"kCoderPreKeyWasAccep
    return self;
 }

- (id)initWithCoder:(NSCoder *)aDecoder{
+- (nullable id)initWithCoder:(NSCoder *)aDecoder{
    return [self initWithId:[aDecoder decodeIntForKey:kCoderPreKeyId]
                     keyPair:[aDecoder decodeObjectOfClass:[ECKeyPair class] forKey:kCoderPreKeyPair]
                   signature:[aDecoder decodeObjectOfClass:[NSData class] forKey:kCoderPreKeySignature]
@ -75,3 +81,5 @@ static NSString *const kCoderPreKeyWasAcceptedByService = @"kCoderPreKeyWasAccep
 }

@end
+
+NS_ASSUME_NONNULL_END
--- a/AxolotlKit/Classes/SessionCipher.h
+++ b/AxolotlKit/Classes/SessionCipher.h
@ -1,11 +1,12 @@
 //
-//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
 //

 #import "AxolotlStore.h"
 #import "IdentityKeyStore.h"
 #import "PreKeyStore.h"
 #import "PreKeyWhisperMessage.h"
+#import "SPKProtocolContext.h"
 #import "SessionState.h"
 #import "SessionStore.h"
 #import "SignedPreKeyStore.h"
@ -24,20 +25,22 @@ NS_ASSUME_NONNULL_BEGIN
 // identity and session store writes are coordinated and/or occur within a single
 // transaction.
 - (id<CipherMessage>)throws_encryptMessage:(NSData *)paddedMessage
-                           protocolContext:(nullable id)protocolContext NS_SWIFT_UNAVAILABLE("throws objc exceptions");
+                           protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext NS_SWIFT_UNAVAILABLE("throws objc exceptions");
 - (nullable id<CipherMessage>)encryptMessage:(NSData *)paddedMessage
-                             protocolContext:(nullable id)protocolContext
+                             protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
                                       error:(NSError **)outError;

 - (NSData *)throws_decrypt:(id<CipherMessage>)whisperMessage
-           protocolContext:(nullable id)protocolContext NS_SWIFT_UNAVAILABLE("throws objc exceptions");
+           protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext NS_SWIFT_UNAVAILABLE("throws objc exceptions");
 - (nullable NSData *)decrypt:(id<CipherMessage>)whisperMessage
-             protocolContext:(nullable id)protocolContext
+             protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
                       error:(NSError **)outError;

- (int)throws_remoteRegistrationId:(nullable id)protocolContext NS_SWIFT_UNAVAILABLE("throws objc exceptions");
+- (int)throws_remoteRegistrationId:(nullable id<SPKProtocolReadContext>)protocolContext
+    NS_SWIFT_UNAVAILABLE("throws objc exceptions");

- (int)throws_sessionVersion:(nullable id)protocolContext NS_SWIFT_UNAVAILABLE("throws objc exceptions");
+- (int)throws_sessionVersion:(nullable id<SPKProtocolReadContext>)protocolContext
+    NS_SWIFT_UNAVAILABLE("throws objc exceptions");

@end

--- a/AxolotlKit/Classes/SessionCipher.m
+++ b/AxolotlKit/Classes/SessionCipher.m
@ -1,5 +1,5 @@
 //
-//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
 //

 #import "SessionCipher.h"
@ -20,6 +20,7 @@
 #import <Curve25519Kit/Ed25519.h>
 #import <HKDFKit/HKDFKit.h>
 #import <SignalCoreKit/SCKExceptionWrapper.h>
+#import <SignalCoreKit/NSData+OWS.h>

 NS_ASSUME_NONNULL_BEGIN

@ -69,6 +70,7 @@ NS_ASSUME_NONNULL_BEGIN
        _deviceId = deviceId;
        _sessionStore = sessionStore;
        _identityKeyStore = identityKeyStore;
+        _prekeyStore = preKeyStore;
        _sessionBuilder = [[SessionBuilder alloc] initWithSessionStore:sessionStore
                                                           preKeyStore:preKeyStore
                                                     signedPreKeyStore:signedPreKeyStore
@ -81,7 +83,7 @@ NS_ASSUME_NONNULL_BEGIN
 }

 - (nullable id<CipherMessage>)encryptMessage:(NSData *)paddedMessage
-                             protocolContext:(nullable id)protocolContext
+                             protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
                                       error:(NSError **)outError
 {
    __block id<CipherMessage> result;
@ -94,7 +96,7 @@ NS_ASSUME_NONNULL_BEGIN
    return result;
 }

- (id<CipherMessage>)throws_encryptMessage:(NSData *)paddedMessage protocolContext:(nullable id)protocolContext
+- (id<CipherMessage>)throws_encryptMessage:(NSData *)paddedMessage protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    OWSAssert(paddedMessage);

@ -111,7 +113,7 @@ NS_ASSUME_NONNULL_BEGIN
                                         recipientId:self.recipientId
                                           direction:TSMessageDirectionOutgoing
                                     protocolContext:protocolContext]) {
-        DDLogWarn(
+        OWSLogWarn(
            @"%@ Previously known identity key for while encrypting for recipient: %@", self.tag, self.recipientId);
        @throw [NSException exceptionWithName:UntrustedIdentityKeyException
                                       reason:@"There is a previously known identity key."
@ -139,7 +141,8 @@ NS_ASSUME_NONNULL_BEGIN
        PendingPreKey *items = [sessionState unacknowledgedPreKeyMessageItems];
        int localRegistrationId = [sessionState localRegistrationId];

-        DDLogInfo(@"Building PreKeyWhisperMessage for: %@ with preKeyId: %d", self.recipientId, items.preKeyId);
+        OWSLogInfo(@"Building PreKeyWhisperMessage for: %@.%lu with preKeyId: %d",
+                  self.recipientId, (unsigned long) self.deviceId, items.preKeyId);

        cipherMessage =
            [[PreKeyWhisperMessage alloc] init_throws_withWhisperMessage:cipherMessage
@ -160,7 +163,7 @@ NS_ASSUME_NONNULL_BEGIN
 }

 - (nullable NSData *)decrypt:(id<CipherMessage>)whisperMessage
-             protocolContext:(nullable id)protocolContext
+             protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
                       error:(NSError **)outError
 {
    __block NSData *_Nullable result;
@ -173,7 +176,7 @@ NS_ASSUME_NONNULL_BEGIN
    return result;
 }

- (NSData *)throws_decrypt:(id<CipherMessage>)whisperMessage protocolContext:(nullable id)protocolContext
+- (NSData *)throws_decrypt:(id<CipherMessage>)whisperMessage protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    OWSAssert(whisperMessage);

@ -198,7 +201,7 @@ NS_ASSUME_NONNULL_BEGIN
 }

 - (NSData *)throws_decryptPreKeyWhisperMessage:(PreKeyWhisperMessage *)preKeyWhisperMessage
-                               protocolContext:(nullable id)protocolContext
+                               protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    OWSAssert(preKeyWhisperMessage);

@ -218,13 +221,14 @@ NS_ASSUME_NONNULL_BEGIN

    // If there was an unsigned PreKey
    if (unsignedPreKeyId >= 0) {
-        [self.prekeyStore removePreKey:unsignedPreKeyId];
+        [self.prekeyStore removePreKey:unsignedPreKeyId
+                       protocolContext:protocolContext];
    }
    
    return plaintext;
 }

- (NSData *)throws_decryptWhisperMessage:(WhisperMessage *)whisperMessage protocolContext:(nullable id)protocolContext
+- (NSData *)throws_decryptWhisperMessage:(WhisperMessage *)whisperMessage protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    OWSAssert(whisperMessage);

@ -234,20 +238,27 @@ NS_ASSUME_NONNULL_BEGIN
                                               whisperMessage:whisperMessage
                                              protocolContext:protocolContext];

-    if (![self.identityKeyStore isTrustedIdentityKey:sessionRecord.sessionState.remoteIdentityKey
-                                         recipientId:self.recipientId
-                                           direction:TSMessageDirectionIncoming
-                                     protocolContext:protocolContext]) {
-        DDLogWarn(
-            @"%@ Previously known identity key for while decrypting from recipient: %@", self.tag, self.recipientId);
-        @throw [NSException exceptionWithName:UntrustedIdentityKeyException
-                                       reason:@"There is a previously known identity key."
-                                     userInfo:@{}];
+    // Our current session state may not have a remote identity key
+    // if we decrypted this message using an old session. It's safe
+    // to ignore this, as the identity key message was already surfaced
+    // when it originally changed.
+    if (sessionRecord.sessionState.remoteIdentityKey) {
+        if (![self.identityKeyStore isTrustedIdentityKey:sessionRecord.sessionState.remoteIdentityKey
+                                             recipientId:self.recipientId
+                                               direction:TSMessageDirectionIncoming
+                                         protocolContext:protocolContext]) {
+            OWSLogWarn(
+                @"%@ Previously known identity key for while decrypting from recipient: %@", self.tag, self.recipientId);
+            @throw [NSException exceptionWithName:UntrustedIdentityKeyException
+                                           reason:@"There is a previously known identity key."
+                                         userInfo:@{}];
+        }
+
+        [self.identityKeyStore saveRemoteIdentity:sessionRecord.sessionState.remoteIdentityKey
+                                      recipientId:self.recipientId
+                                  protocolContext:protocolContext];
    }

-    [self.identityKeyStore saveRemoteIdentity:sessionRecord.sessionState.remoteIdentityKey
-                                  recipientId:self.recipientId
-                              protocolContext:protocolContext];
    [self.sessionStore storeSession:self.recipientId
                           deviceId:self.deviceId
                            session:sessionRecord
@ -256,9 +267,14 @@ NS_ASSUME_NONNULL_BEGIN
    return plaintext;
 }

+- (void)logDecryptionFailureForWhisperMessage:(WhisperMessage *)whisperMessage sessionState:(SessionState *)sessionState
+{
+    OWSFailDebug(@"Failed to decrypt whisper message with ratchet key: %@ and counter: %d. Session loaded using recipientId: %@ and deviceId: %d. Local session has base key: %@ and counter: %d", whisperMessage.senderRatchetKey.hexadecimalString, whisperMessage.counter, self.recipientId, self.deviceId, sessionState.senderRatchetKey.hexadecimalString, sessionState.previousCounter);
+}
+
 - (NSData *)throws_decryptWithSessionRecord:(SessionRecord *)sessionRecord
                             whisperMessage:(WhisperMessage *)whisperMessage
-                            protocolContext:(nullable id)protocolContext
+                            protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    OWSAssert(sessionRecord);
    OWSAssert(whisperMessage);
@ -270,51 +286,49 @@ NS_ASSUME_NONNULL_BEGIN
        NSData *decryptedData = [self throws_decryptWithSessionState:sessionState
                                                      whisperMessage:whisperMessage
                                                     protocolContext:protocolContext];
-        DDLogDebug(@"%@ successfully decrypted with current session state: %@", self.tag, sessionState);
+        OWSLogDebug(@"%@ successfully decrypted with current session state: %@", self.tag, sessionState);
        return decryptedData;
    }
    @catch (NSException *exception) {
        if ([exception.name isEqualToString:InvalidMessageException]) {
            [exceptions addObject:exception];
        } else {
+            [self logDecryptionFailureForWhisperMessage:whisperMessage sessionState:sessionState];
            @throw exception;
        }
    }

    // If we can decrypt the message with an "old" session state, that means the sender is using an "old" session.
-    // In which case, we promote that session to "active" so as to converge on a single session for sending/receiving.
-    __block NSUInteger stateToPromoteIdx;
-    __block NSData *decryptedData;
+    // We can continue to receive messages from this sender, but we will send to them using our current session.
+    __block NSData *_Nullable decryptedData;
    [[sessionRecord previousSessionStates]
        enumerateObjectsUsingBlock:^(SessionState *_Nonnull previousState, NSUInteger idx, BOOL *_Nonnull stop) {
            @try {
                decryptedData = [self throws_decryptWithSessionState:previousState
                                                      whisperMessage:whisperMessage
                                                     protocolContext:protocolContext];
-                DDLogInfo(@"%@ successfully decrypted with PREVIOUS session state: %@", self.tag, previousState);
+                OWSLogInfo(@"%@ successfully decrypted with PREVIOUS session state: %@", self.tag, previousState);
                OWSAssert(decryptedData != nil);
-                stateToPromoteIdx = idx;
                *stop = YES;
            } @catch (NSException *exception) {
+                if (![exception.name isEqualToString:InvalidMessageException]) {
+                    [self logDecryptionFailureForWhisperMessage:whisperMessage sessionState:sessionState];
+                }
+
                [exceptions addObject:exception];
            }
        }];

    if (decryptedData) {
-        SessionState *sessionStateToPromote = [sessionRecord previousSessionStates][stateToPromoteIdx];
-        OWSAssert(sessionStateToPromote != nil);
-        DDLogInfo(@"%@ promoting session: %@", self.tag, sessionStateToPromote);
-        [[sessionRecord previousSessionStates] removeObjectAtIndex:stateToPromoteIdx];
-        [sessionRecord promoteState:sessionStateToPromote];
-
        return decryptedData;
    }

    BOOL containsActiveSession =
        [self.sessionStore containsSession:self.recipientId deviceId:self.deviceId protocolContext:protocolContext];
-    DDLogError(@"%@ No valid session for recipient: %@ containsActiveSession: %@, previousStates: %lu",
+    OWSLogError(@"%@ No valid session for recipient: %@.%lu containsActiveSession: %@, previousStates: %lu",
        self.tag,
        self.recipientId,
+        (unsigned long) self.deviceId,
        (containsActiveSession ? @"YES" : @"NO"),
        (unsigned long)sessionRecord.previousSessionStates.count);

@ -334,7 +348,7 @@ NS_ASSUME_NONNULL_BEGIN

 - (NSData *)throws_decryptWithSessionState:(SessionState *)sessionState
                            whisperMessage:(WhisperMessage *)whisperMessage
-                           protocolContext:(nullable id)protocolContext
+                           protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    OWSAssert(sessionState);
    OWSAssert(whisperMessage);
@ -383,10 +397,10 @@ NS_ASSUME_NONNULL_BEGIN

    @try {
        if ([sessionState hasReceiverChain:theirEphemeral]) {
-            DDLogInfo(@"%@ %@.%d has existing receiver chain.", self.tag, self.recipientId, self.deviceId);
+            OWSLogInfo(@"%@ %@.%d has existing receiver chain.", self.tag, self.recipientId, self.deviceId);
            return [sessionState receiverChainKey:theirEphemeral];
        } else{
-            DDLogInfo(@"%@ %@.%d creating new chains.", self.tag, self.recipientId, self.deviceId);
+            OWSLogInfo(@"%@ %@.%d creating new chains.", self.tag, self.recipientId, self.deviceId);
            RootKey *rootKey = [sessionState rootKey];
            OWSAssert(rootKey.keyData.length == 32);

@ -442,7 +456,7 @@ NS_ASSUME_NONNULL_BEGIN
        }
    }

-    NSUInteger kCounterLimit = 2000;
+    NSUInteger kCounterLimit = 25000;
    int counterOffset;
    if (__builtin_sub_overflow(counter, chainKey.index, &counterOffset)) {
        OWSFailDebug(@"Overflow while calculating counter offset");
@ -484,7 +498,7 @@ NS_ASSUME_NONNULL_BEGIN
    return versionByte;
 }

- (int)throws_remoteRegistrationId:(nullable id)protocolContext
+- (int)throws_remoteRegistrationId:(nullable id<SPKProtocolReadContext>)protocolContext
 {
    SessionRecord *_Nullable record =
        [self.sessionStore loadSession:self.recipientId deviceId:_deviceId protocolContext:protocolContext];
@ -496,7 +510,7 @@ NS_ASSUME_NONNULL_BEGIN
    return record.sessionState.remoteRegistrationId;
 }

- (int)throws_sessionVersion:(nullable id)protocolContext
+- (int)throws_sessionVersion:(nullable id<SPKProtocolReadContext>)protocolContext
 {
    SessionRecord *_Nullable record =
        [self.sessionStore loadSession:self.recipientId deviceId:_deviceId protocolContext:protocolContext];
--- a/AxolotlKit/Classes/Sessions/SessionBuilder.h
+++ b/AxolotlKit/Classes/Sessions/SessionBuilder.h
@ -1,11 +1,12 @@
 //
-//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
 //

 #import "AxolotlStore.h"
 #import "IdentityKeyStore.h"
 #import "PreKeyBundle.h"
 #import "PreKeyStore.h"
+#import "SPKProtocolContext.h"
 #import "SessionStore.h"
 #import "SignedPreKeyStore.h"
 #import <Foundation/Foundation.h>
@ -30,14 +31,14 @@ extern const int kPreKeyOfLastResortId;
                            deviceId:(int)deviceId;

 - (void)throws_processPrekeyBundle:(PreKeyBundle *)preKeyBundle
-                   protocolContext:(nullable id)protocolContext NS_SWIFT_UNAVAILABLE("throws objc exceptions");
+                   protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext NS_SWIFT_UNAVAILABLE("throws objc exceptions");
 - (BOOL)processPrekeyBundle:(PreKeyBundle *)preKeyBundle
-            protocolContext:(nullable id)protocolContext
+            protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
                      error:(NSError **)outError;

 - (int)throws_processPrekeyWhisperMessage:(PreKeyWhisperMessage *)message
                              withSession:(SessionRecord *)sessionRecord
-                          protocolContext:(nullable id)protocolContext NS_SWIFT_UNAVAILABLE("throws objc exceptions");
+                          protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext NS_SWIFT_UNAVAILABLE("throws objc exceptions");

@end

--- a/AxolotlKit/Classes/Sessions/SessionBuilder.m
+++ b/AxolotlKit/Classes/Sessions/SessionBuilder.m
@ -1,5 +1,5 @@
 //
-//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
 //

 #import "SessionBuilder.h"
@ -80,7 +80,7 @@ const int kPreKeyOfLastResortId = 0xFFFFFF;
 }

 - (BOOL)processPrekeyBundle:(PreKeyBundle *)preKeyBundle
-            protocolContext:(nullable id)protocolContext
+            protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
                      error:(NSError **)outError
 {
    return [SCKExceptionWrapper
@ -90,7 +90,7 @@ const int kPreKeyOfLastResortId = 0xFFFFFF;
           error:outError];
 }

- (void)throws_processPrekeyBundle:(PreKeyBundle *)preKeyBundle protocolContext:(nullable id)protocolContext
+- (void)throws_processPrekeyBundle:(PreKeyBundle *)preKeyBundle protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    OWSAssert(preKeyBundle);

@ -146,12 +146,6 @@ const int kPreKeyOfLastResortId = 0xFFFFFF;
    BOOL previousIdentityExisted = [self.identityStore saveRemoteIdentity:theirIdentityKey
                                                              recipientId:self.recipientId
                                                          protocolContext:protocolContext];
-    if (previousIdentityExisted) {
-        DDLogInfo(@"%@ PKBundle removing previous session states for changed identity for recipient:%@",
-            self.tag,
-            self.recipientId);
-        [sessionRecord removePreviousSessionStates];
-    }

    [self.sessionStore storeSession:self.recipientId
                           deviceId:self.deviceId
@ -161,7 +155,7 @@ const int kPreKeyOfLastResortId = 0xFFFFFF;

 - (int)throws_processPrekeyWhisperMessage:(PreKeyWhisperMessage *)message
                              withSession:(SessionRecord *)sessionRecord
-                          protocolContext:(nullable id)protocolContext
+                          protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    OWSAssert(message);
    OWSAssert(sessionRecord);
@ -197,7 +191,7 @@ const int kPreKeyOfLastResortId = 0xFFFFFF;

 - (int)throws_processPrekeyV3:(PreKeyWhisperMessage *)message
                  withSession:(SessionRecord *)sessionRecord
-              protocolContext:(nullable id)protocolContext
+              protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    OWSAssert(message);
    OWSAssert(sessionRecord);
@ -208,11 +202,28 @@ const int kPreKeyOfLastResortId = 0xFFFFFF;
        return -1;
    }

-    ECKeyPair *ourSignedPrekey = [self.signedPreKeyStore throws_loadSignedPrekey:message.signedPrekeyId].keyPair;
+    SignedPreKeyRecord *_Nullable signedPreKeyRecord = [self.signedPreKeyStore loadSignedPreKey:message.signedPrekeyId
+                                                                                protocolContext:protocolContext];
+    if (signedPreKeyRecord == nil) {
+        OWSLogWarn(@"Signed prekey id: %lu, prekey id: %lu.",
+                  (unsigned long) message.signedPrekeyId,
+                  (unsigned long) message.prekeyID);
+        OWSLogWarn(@"Available signed prekey ids: %@",
+                  [self.signedPreKeyStore availableSignedPreKeyIdsWithProtocolContext:protocolContext]);
+
+        OWSRaiseException(InvalidKeyIdException, @"No signed prekey found matching key id");
+    }
+    ECKeyPair *ourSignedPrekey = signedPreKeyRecord.keyPair;

    ECKeyPair *_Nullable ourOneTimePreKey;
    if (message.prekeyID >= 0) {
-        ourOneTimePreKey = [self.prekeyStore throws_loadPreKey:message.prekeyID].keyPair;
+        PreKeyRecord *_Nullable preKey = [self.prekeyStore loadPreKey:message.prekeyID
+                                                      protocolContext:protocolContext];
+        if (preKey == nil) {
+            OWSFailDebug(@"Missing prekeyID: %lu", (unsigned long) message.prekeyID);
+            OWSRaiseException(InvalidKeyIdException, @"No pre key found matching key id");
+        }
+        ourOneTimePreKey = preKey.keyPair;
    } else {
        DDLogWarn(@"%@ Processing PreKey message which had no one-time prekey.", self.tag);
    }
--- a/AxolotlKit/Classes/Sessions/SessionRecord.h
+++ b/AxolotlKit/Classes/Sessions/SessionRecord.h
@ -11,13 +11,11 @@

 - (BOOL)hasSessionState:(int)version baseKey:(NSData*)aliceBaseKey;
 - (SessionState*)sessionState;
- (NSMutableArray<SessionState *> *)previousSessionStates;
+- (NSArray<SessionState *> *)previousSessionStates;

- (void)removePreviousSessionStates;
 - (BOOL)isFresh;
 - (void)markAsUnFresh;
 - (void)archiveCurrentState;
- (void)promoteState:(SessionState*)promotedState;
 - (void)setState:(SessionState*)sessionState;

@end
--- a/AxolotlKit/Classes/Sessions/SessionRecord.m
+++ b/AxolotlKit/Classes/Sessions/SessionRecord.m
@ -71,16 +71,11 @@
    return _sessionState;
 }

- (NSMutableArray<SessionState *> *)previousSessionStates
+- (NSArray<SessionState *> *)previousSessionStates
 {
    return _previousStates;
 }

- (void)removePreviousSessionStates
-{
-    [_previousStates removeAllObjects];
-}
-
 - (BOOL)isFresh{
    return _fresh;
 }
@ -91,6 +86,10 @@
 }

 - (void)archiveCurrentState{
+    if (self.sessionState.isFresh) {
+        OWSLogInfo(@"Skipping archive, current session state is fresh.");
+        return;
+    }
    [self promoteState:[SessionState new]];
 }

@ -103,7 +102,7 @@
        ows_sub_overflow(self.previousStates.count, ARCHIVED_STATES_MAX_LENGTH, &deleteCount);
        NSIndexSet *indexesToDelete =
            [NSIndexSet indexSetWithIndexesInRange:NSMakeRange(ARCHIVED_STATES_MAX_LENGTH, deleteCount)];
-        [self.previousSessionStates removeObjectsAtIndexes:indexesToDelete];
+        [self.previousStates removeObjectsAtIndexes:indexesToDelete];
    }
 }

--- a/AxolotlKit/Classes/Sessions/SessionState.h
+++ b/AxolotlKit/Classes/Sessions/SessionState.h
@ -39,6 +39,8 @@
@property(nonatomic)int remoteRegistrationId;
@property(nonatomic)int localRegistrationId;

+@property (nonatomic, readonly) BOOL isFresh;
+
 - (NSData*)senderRatchetKey;
 - (ECKeyPair*)senderRatchetKeyPair;

--- a/AxolotlKit/Classes/Sessions/SessionState.m
+++ b/AxolotlKit/Classes/Sessions/SessionState.m
@ -119,6 +119,11 @@ static NSString* const kCoderPendingPrekey    = @"kCoderPendingPrekey";
    [aCoder encodeObject:self.pendingPreKey forKey:kCoderPendingPrekey];
 }

+- (BOOL)isFresh
+{
+    return self.remoteIdentityKey == nil && self.localIdentityKey == nil && self.sendingChain == nil && self.receivingChains.count == 0 && self.pendingPreKey == nil;
+}
+
 - (NSData*)senderRatchetKey{
    return [[self senderRatchetKeyPair] publicKey];
 }
--- a/AxolotlKit/Classes/State/IdentityKeyStore.h
+++ b/AxolotlKit/Classes/State/IdentityKeyStore.h
@ -1,7 +1,8 @@
 //
-//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
 //

+#import "SPKProtocolContext.h"
 #import <Foundation/Foundation.h>

 NS_ASSUME_NONNULL_BEGIN
@ -17,9 +18,9 @@ typedef NS_ENUM(NSInteger, TSMessageDirection) {
 // See a discussion of the protocolContext in SessionCipher.h.
@protocol IdentityKeyStore <NSObject>

- (nullable ECKeyPair *)identityKeyPair:(nullable id)protocolContext;
+- (nullable ECKeyPair *)identityKeyPair:(nullable id<SPKProtocolWriteContext>)protocolContext;

- (int)localRegistrationId:(nullable id)protocolContext;
+- (int)localRegistrationId:(nullable id<SPKProtocolWriteContext>)protocolContext;

 /**
 * Record a recipients identity key
@ -32,7 +33,7 @@ typedef NS_ENUM(NSInteger, TSMessageDirection) {
 */
 - (BOOL)saveRemoteIdentity:(NSData *)identityKey
               recipientId:(NSString *)recipientId
-           protocolContext:(nullable id)protocolContext;
+           protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext;

 /**
 * @param   identityKey key data used to identify the recipient
@ -46,11 +47,12 @@ typedef NS_ENUM(NSInteger, TSMessageDirection) {
 - (BOOL)isTrustedIdentityKey:(NSData *)identityKey
                 recipientId:(NSString *)recipientId
                   direction:(TSMessageDirection)direction
-             protocolContext:(nullable id)protocolContext;
+             protocolContext:(nullable id<SPKProtocolReadContext>)protocolContext;

 - (nullable NSData *)identityKeyForRecipientId:(NSString *)recipientId;

- (nullable NSData *)identityKeyForRecipientId:(NSString *)recipientId protocolContext:(nullable id)protocolContext;
+- (nullable NSData *)identityKeyForRecipientId:(NSString *)recipientId
+                               protocolContext:(nullable id<SPKProtocolReadContext>)protocolContext;

@end

--- a/AxolotlKit/Classes/State/PreKeyStore.h
+++ b/AxolotlKit/Classes/State/PreKeyStore.h
@ -1,5 +1,5 @@
 //
-//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
 //

 #import "PreKeyRecord.h"
@ -9,13 +9,14 @@ NS_ASSUME_NONNULL_BEGIN

@protocol PreKeyStore <NSObject>

- (PreKeyRecord *)throws_loadPreKey:(int)preKeyId NS_SWIFT_UNAVAILABLE("throws objc exceptions");
+- (nullable PreKeyRecord *)loadPreKey:(int)preKeyId
+                      protocolContext:(nullable id<SPKProtocolReadContext>)protocolContext;

- (void)storePreKey:(int)preKeyId preKeyRecord:(PreKeyRecord *)record;
+- (void)storePreKey:(int)preKeyId preKeyRecord:(PreKeyRecord *)record
+    protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext;

- (BOOL)containsPreKey:(int)preKeyId;
-
- (void)removePreKey:(int)preKeyId;
+- (void)removePreKey:(int)preKeyId
+     protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext;

@end

--- a/AxolotlKit/Classes/State/SessionStore.h
+++ b/AxolotlKit/Classes/State/SessionStore.h
@ -1,7 +1,8 @@
 //
-//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
 //

+#import "SPKProtocolContext.h"
 #import "SessionRecord.h"
 #import <Foundation/Foundation.h>

@ -20,24 +21,24 @@ NS_ASSUME_NONNULL_BEGIN
 */
 - (SessionRecord *)loadSession:(NSString *)contactIdentifier
                      deviceId:(int)deviceId
-               protocolContext:(nullable id)protocolContext;
+               protocolContext:(nullable id<SPKProtocolReadContext>)protocolContext;

- (NSArray *)subDevicesSessions:(NSString *)contactIdentifier protocolContext:(nullable id)protocolContext __attribute__((deprecated));
+- (NSArray *)subDevicesSessions:(NSString *)contactIdentifier protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext __attribute__((deprecated));

 - (void)storeSession:(NSString *)contactIdentifier
            deviceId:(int)deviceId
             session:(SessionRecord *)session
-     protocolContext:(nullable id)protocolContext;
+     protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext;

 - (BOOL)containsSession:(NSString *)contactIdentifier
               deviceId:(int)deviceId
-        protocolContext:(nullable id)protocolContext;
+        protocolContext:(nullable id<SPKProtocolReadContext>)protocolContext;

 - (void)deleteSessionForContact:(NSString *)contactIdentifier
                       deviceId:(int)deviceId
-                protocolContext:(nullable id)protocolContext;
+                protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext;

- (void)deleteAllSessionsForContact:(NSString *)contactIdentifier protocolContext:(nullable id)protocolContext;
+- (void)deleteAllSessionsForContact:(NSString *)contactIdentifier protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext;

@end

--- a/AxolotlKit/Classes/State/SignedPreKeyStore.h
+++ b/AxolotlKit/Classes/State/SignedPreKeyStore.h
@ -1,5 +1,5 @@
 //
-//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
 //

 #import "SignedPrekeyRecord.h"
@ -9,17 +9,22 @@ NS_ASSUME_NONNULL_BEGIN

@protocol SignedPreKeyStore <NSObject>

- (SignedPreKeyRecord *)throws_loadSignedPrekey:(int)signedPreKeyId NS_SWIFT_UNAVAILABLE("throws objc exceptions");
+- (nullable SignedPreKeyRecord *)loadSignedPreKey:(int)signedPreKeyId
+                                  protocolContext:(nullable id<SPKProtocolReadContext>)protocolContext;

- (nullable SignedPreKeyRecord *)loadSignedPrekeyOrNil:(int)signedPreKeyId;
+- (NSArray<SignedPreKeyRecord *> *)loadSignedPreKeysWithProtocolContext:(nullable id<SPKProtocolReadContext>)protocolContext;

- (NSArray<SignedPreKeyRecord *> *)loadSignedPreKeys;
+- (void)storeSignedPreKey:(int)signedPreKeyId
+       signedPreKeyRecord:(SignedPreKeyRecord *)signedPreKeyRecord
+          protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext;

- (void)storeSignedPreKey:(int)signedPreKeyId signedPreKeyRecord:(SignedPreKeyRecord *)signedPreKeyRecord;
+- (BOOL)containsSignedPreKey:(int)signedPreKeyId
+             protocolContext:(nullable id<SPKProtocolReadContext>)protocolContext;

- (BOOL)containsSignedPreKey:(int)signedPreKeyId;
+- (void)removeSignedPreKey:(int)signedPreKeyId
+           protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext;

- (void)removeSignedPreKey:(int)signedPrekeyId;
+- (NSArray<NSString *> *)availableSignedPreKeyIdsWithProtocolContext:(nullable id<SPKProtocolReadContext>)protocolContext;

@end

--- a/AxolotlKit/Classes/TestUtils/SPKMockProtocolStore.m
+++ b/AxolotlKit/Classes/TestUtils/SPKMockProtocolStore.m
@ -1,5 +1,5 @@
 //
-//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
 //

 #import "SPKMockProtocolStore.h"
@ -52,31 +52,13 @@ NS_ASSUME_NONNULL_BEGIN

 #pragma mark Signed PreKey Store

- (SignedPreKeyRecord *)throws_loadSignedPrekey:(int)signedPreKeyId
+- (nullable SignedPreKeyRecord *)loadSignedPreKey:(int)signedPreKeyId
+                                  protocolContext:(nullable id<SPKProtocolReadContext>)protocolContext
 {
-    if (![[self.signedPreKeyStore allKeys] containsObject:[NSNumber numberWithInt:signedPreKeyId]]) {
-        @throw [NSException exceptionWithName:InvalidKeyIdException reason:@"No such signedprekeyrecord" userInfo:nil];
-    }
-
    return [self.signedPreKeyStore objectForKey:[NSNumber numberWithInt:signedPreKeyId]];
 }

- (nullable SignedPreKeyRecord *)loadSignedPrekeyOrNil:(int)signedPreKeyId
-{
-    if ([self containsSignedPreKey:signedPreKeyId]) {
-        @try {
-            // Given that we've checked for `contains` this really shouldn't fail.
-            return [self throws_loadSignedPrekey:signedPreKeyId];
-        } @catch (NSException *exception) {
-            OWSFailDebug(@"unexpected exception: %@", exception);
-            return nil;
-        }
-    } else {
-        return nil;
-    }
-}
-
- (NSArray<SignedPreKeyRecord *> *)loadSignedPreKeys
+- (NSArray<SignedPreKeyRecord *> *)loadSignedPreKeysWithProtocolContext:(nullable id<SPKProtocolReadContext>)protocolContext
 {
    NSMutableArray *results = [NSMutableArray array];

@ -87,12 +69,20 @@ NS_ASSUME_NONNULL_BEGIN
    return results;
 }

- (void)storeSignedPreKey:(int)signedPreKeyId signedPreKeyRecord:(SignedPreKeyRecord *)signedPreKeyRecord
+- (NSArray<NSString *> *)availableSignedPreKeyIdsWithProtocolContext:(nullable id<SPKProtocolReadContext>)protocolContext
+{
+    return @[];
+}
+
+- (void)storeSignedPreKey:(int)signedPreKeyId
+       signedPreKeyRecord:(SignedPreKeyRecord *)signedPreKeyRecord
+          protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    [self.signedPreKeyStore setObject:signedPreKeyRecord forKey:[NSNumber numberWithInteger:signedPreKeyId]];
 }

 - (BOOL)containsSignedPreKey:(int)signedPreKeyId
+             protocolContext:(nullable id<SPKProtocolReadContext>)protocolContext
 {
    if ([[self.signedPreKeyStore allKeys] containsObject:[NSNumber numberWithInteger:signedPreKeyId]]) {
        return TRUE;
@ -101,19 +91,17 @@ NS_ASSUME_NONNULL_BEGIN
    return FALSE;
 }

- (void)removeSignedPreKey:(int)signedPrekeyId
+- (void)removeSignedPreKey:(int)signedPreKeyId
+           protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
-    [self.signedPreKeyStore removeObjectForKey:[NSNumber numberWithInteger:signedPrekeyId]];
+    [self.signedPreKeyStore removeObjectForKey:[NSNumber numberWithInteger:signedPreKeyId]];
 }

 #pragma mark PreKey Store

- (PreKeyRecord *)throws_loadPreKey:(int)preKeyId
+- (nullable PreKeyRecord *)loadPreKey:(int)preKeyId
+                      protocolContext:(nullable id<SPKProtocolReadContext>)protocolContext;
 {
-    if (![[self.preKeyStore allKeys] containsObject:[NSNumber numberWithInt:preKeyId]]) {
-        @throw [NSException exceptionWithName:InvalidKeyIdException reason:@"No such signedprekeyrecord" userInfo:nil];
-    }
-
    return [self.preKeyStore objectForKey:[NSNumber numberWithInt:preKeyId]];
 }

@ -129,39 +117,32 @@ NS_ASSUME_NONNULL_BEGIN
 }

 - (void)storePreKey:(int)preKeyId preKeyRecord:(PreKeyRecord *)record
+    protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    [self.preKeyStore setObject:record forKey:[NSNumber numberWithInt:preKeyId]];
 }

- (BOOL)containsPreKey:(int)preKeyId
-{
-    if ([[self.preKeyStore allKeys] containsObject:[NSNumber numberWithInteger:preKeyId]]) {
-        return TRUE;
-    }
-
-    return FALSE;
-}
-
 - (void)removePreKey:(int)preKeyId
+     protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    [self.preKeyStore removeObjectForKey:[NSNumber numberWithInt:preKeyId]];
 }

 #pragma mark IdentityKeyStore

- (nullable ECKeyPair *)identityKeyPair:(nullable id)protocolContext
+- (nullable ECKeyPair *)identityKeyPair:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    return self.identityKeyPair;
 }

- (int)localRegistrationId:(nullable id)protocolContext
+- (int)localRegistrationId:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    return self.localRegistrationId;
 }

 - (BOOL)saveRemoteIdentity:(NSData *)identityKey
               recipientId:(NSString *)recipientId
-           protocolContext:(nullable id)protocolContext
+           protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    NSData *existingKey = [self.trustedKeys objectForKey:recipientId];

@ -176,7 +157,7 @@ NS_ASSUME_NONNULL_BEGIN
 - (BOOL)isTrustedIdentityKey:(NSData *)identityKey
                 recipientId:(NSString *)recipientId
                   direction:(TSMessageDirection)direction
-             protocolContext:(nullable id)protocolContext
+             protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    NSData *data = [self.trustedKeys objectForKey:recipientId];
    if (!data) {
@ -202,7 +183,8 @@ NS_ASSUME_NONNULL_BEGIN
    return [self identityKeyForRecipientId:recipientId protocolContext:nil];
 }

- (nullable NSData *)identityKeyForRecipientId:(NSString *)recipientId protocolContext:(nullable id)protocolContext
+- (nullable NSData *)identityKeyForRecipientId:(NSString *)recipientId
+                               protocolContext:(nullable id<SPKProtocolReadContext>)protocolContext
 {
    NSData *_Nullable data = [self.trustedKeys objectForKey:recipientId];
    return data;
@ -212,7 +194,7 @@ NS_ASSUME_NONNULL_BEGIN

 - (SessionRecord *)loadSession:(NSString *)contactIdentifier
                      deviceId:(int)deviceId
-               protocolContext:(nullable id)protocolContext
+               protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    SessionRecord *sessionRecord = [[self deviceSessionRecordsForContactIdentifier:contactIdentifier]
        objectForKey:[NSNumber numberWithInteger:deviceId]];
@ -224,10 +206,13 @@ NS_ASSUME_NONNULL_BEGIN
    return sessionRecord;
 }

- (NSArray *)subDevicesSessions:(NSString *)contactIdentifier protocolContext:(nullable id)protocolContext
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-implementations"
+- (NSArray *)subDevicesSessions:(NSString *)contactIdentifier protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    return [[self deviceSessionRecordsForContactIdentifier:contactIdentifier] allKeys];
 }
+#pragma clang diagnostic pop

 - (NSMutableDictionary *)deviceSessionRecordsForContactIdentifier:(NSString *)contactIdentifier
 {
@ -237,7 +222,7 @@ NS_ASSUME_NONNULL_BEGIN
 - (void)storeSession:(NSString *)contactIdentifier
            deviceId:(int)deviceId
             session:(SessionRecord *)session
-     protocolContext:(nullable id)protocolContext
+     protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    NSAssert(session, @"Session can't be nil");
    NSMutableDictionary *deviceSessions = self.sessionRecords[contactIdentifier];
@ -251,7 +236,7 @@ NS_ASSUME_NONNULL_BEGIN

 - (BOOL)containsSession:(NSString *)contactIdentifier
               deviceId:(int)deviceId
-        protocolContext:(nullable id)protocolContext
+        protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {

    if ([[self.sessionRecords objectForKey:contactIdentifier] objectForKey:[NSNumber numberWithInt:deviceId]]) {
@ -262,14 +247,14 @@ NS_ASSUME_NONNULL_BEGIN

 - (void)deleteSessionForContact:(NSString *)contactIdentifier
                       deviceId:(int)deviceId
-                protocolContext:(nullable id)protocolContext
+                protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    NSMutableDictionary<NSNumber *, SessionRecord *> *sessions =
        [self deviceSessionRecordsForContactIdentifier:contactIdentifier];
    [sessions removeObjectForKey:@(deviceId)];
 }

- (void)deleteAllSessionsForContact:(NSString *)contactIdentifier protocolContext:(nullable id)protocolContext
+- (void)deleteAllSessionsForContact:(NSString *)contactIdentifier protocolContext:(nullable id<SPKProtocolWriteContext>)protocolContext
 {
    [self.sessionRecords removeObjectForKey:contactIdentifier];
 }
--- a/AxolotlKit/Classes/Utility/NSData+keyVersionByte.h
+++ b/AxolotlKit/Classes/Utility/NSData+keyVersionByte.h
@ -1,9 +1,11 @@
 //
-//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
 //

 #import <Foundation/Foundation.h>

+NS_ASSUME_NONNULL_BEGIN
+
@interface NSData (keyVersionByte)

 - (instancetype)prependKeyType;
@ -12,3 +14,5 @@
 - (nullable instancetype)removeKeyTypeAndReturnError:(NSError **)outError;

@end
+
+NS_ASSUME_NONNULL_END
--- a/AxolotlKit/Classes/Utility/NSData+keyVersionByte.m
+++ b/AxolotlKit/Classes/Utility/NSData+keyVersionByte.m
@ -1,11 +1,13 @@
 //
-//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
 //

 #import "NSData+keyVersionByte.h"
 #import "AxolotlExceptions.h"
 #import <SignalCoreKit/SCKExceptionWrapper.h>

+NS_ASSUME_NONNULL_BEGIN
+
@implementation NSData (keyVersionByte)

 const Byte DJB_TYPE = 0x05;
@ -46,3 +48,5 @@ const Byte DJB_TYPE = 0x05;
 }

@end
+
+NS_ASSUME_NONNULL_END
--- a/AxolotlKit/Classes/Utility/SPKProtocolContext.h
+++ b/AxolotlKit/Classes/Utility/SPKProtocolContext.h
@ -0,0 +1,17 @@
+//
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@protocol SPKProtocolReadContext <NSObject>
+
+@end
+
+@protocol SPKProtocolWriteContext <SPKProtocolReadContext>
+
+@end
+
+NS_ASSUME_NONNULL_END
--- a/AxolotlKitTests/SessionBuilderTests.m
+++ b/AxolotlKitTests/SessionBuilderTests.m
@ -80,8 +80,16 @@
    XCTAssert([outgoingMessage isKindOfClass:[PreKeyWhisperMessage class]], @"Message should be PreKey type");
    
    PreKeyWhisperMessage *incomingMessage = (PreKeyWhisperMessage*)outgoingMessage;
-    [bobStore storePreKey:31337 preKeyRecord:[[PreKeyRecord alloc] initWithId:bobPreKey.preKeyId keyPair:bobPreKeyPair]];
-    [bobStore storeSignedPreKey:22 signedPreKeyRecord:[[SignedPreKeyRecord alloc] initWithId:22 keyPair:bobSignedPreKeyPair signature:bobSignedPreKeySignature generatedAt:[NSDate date]]];
+    [bobStore storePreKey:31337 preKeyRecord:[[PreKeyRecord alloc] initWithId:bobPreKey.preKeyId
+                                                                      keyPair:bobPreKeyPair
+                                                                    createdAt:[NSDate date]]
+          protocolContext:nil];
+    [bobStore storeSignedPreKey:22
+             signedPreKeyRecord:[[SignedPreKeyRecord alloc] initWithId:22
+                                                               keyPair:bobSignedPreKeyPair
+                                                             signature:bobSignedPreKeySignature
+                                                           generatedAt:[NSDate date]]
+     protocolContext:nil];
    
    SessionCipher *bobSessionCipher = [[SessionCipher alloc] initWithAxolotlStore:bobStore recipientId:ALICE_RECIPIENT_ID deviceId:1];
    [bobSessionCipher throws_decrypt:incomingMessage protocolContext:nil];
@ -89,7 +97,7 @@
    XCTAssert([bobStore containsSession:ALICE_RECIPIENT_ID deviceId:1 protocolContext:nil]);
    XCTAssert([bobStore loadSession:ALICE_RECIPIENT_ID deviceId:1 protocolContext:nil].sessionState.version == 3);
    XCTAssert([bobStore loadSession:ALICE_RECIPIENT_ID deviceId:1 protocolContext:nil].sessionState.aliceBaseKey != nil);
-}
+} 

 /**
 *  Tests the case where an attacker would send a new PreKeyWhisperMessage with another IdentityKey
--- a/AxolotlKitTests/SessionCipherTest.m
+++ b/AxolotlKitTests/SessionCipherTest.m
@ -13,6 +13,10 @@
 #import <Curve25519Kit/Curve25519.h>
 #import <XCTest/XCTest.h>

+@interface SessionRecord (Private)
+- (void)promoteState:(SessionState *)promotedState;
+@end
+
@interface SessionCipherTest : XCTestCase

@property (nonatomic, readonly) NSString *aliceIdentifier;
@ -77,10 +81,11 @@
    XCTAssertNotEqualObjects(initialSessionState, activeSession.sessionState);
    XCTAssertEqualObjects(newSessionState, activeSession.sessionState);

-    // 3.) Bob should promote back the initial session after receiving a message from that old session.
+    // 3.) Bob should decrypt with initial session after receiving a message from that old session,
+    // but importantly *not* promote it to be the active session.
    [self runInteractionWithAliceRecord:aliceSessionRecord bobRecord:bobSessionRecord];
-    XCTAssertNotEqualObjects(newSessionState, activeSession.sessionState);
-    XCTAssertEqualObjects(initialSessionState, activeSession.sessionState);
+    XCTAssertNotEqualObjects(initialSessionState, activeSession.sessionState);
+    XCTAssertEqualObjects(newSessionState, activeSession.sessionState);
    XCTAssertEqual(1, bobSessionRecord.previousSessionStates.count);
    XCTAssertEqual(0, aliceSessionRecord.previousSessionStates.count);
 }
--- a/AxolotlKitTests/Util/ECKeyPair+ECKeyPairTesting.m
+++ b/AxolotlKitTests/Util/ECKeyPair+ECKeyPairTesting.m
@ -7,14 +7,6 @@

 NS_ASSUME_NONNULL_BEGIN

-@interface ECKeyPair (ECKeyPairTestingPrivate)
-
- (nullable id)initWithPublicKey:(NSData *)publicKey privateKey:(NSData *)privateKey;
-
-@end
-
-#pragma mark -
-
@implementation ECKeyPair (testing)

 + (ECKeyPair *)throws_keyPairWithPrivateKey:(NSData *)privateKey publicKey:(NSData *)publicKey
@ -27,7 +19,9 @@ NS_ASSUME_NONNULL_BEGIN
        @throw [NSException exceptionWithName:NSInvalidArgumentException reason:@"Public or Private key is not required size" userInfo:@{@"PrivateKey":privateKey, @"Public Key":publicKey}];
    }

-    ECKeyPair *keyPairCopy = [[ECKeyPair alloc] initWithPublicKey:[publicKey copy] privateKey:[privateKey copy]];
+    NSError *error;
+    ECKeyPair *_Nullable keyPairCopy = [[ECKeyPair alloc] initWithPublicKeyData:[publicKey copy] privateKeyData:[privateKey copy] error:&error];
+    OWSAssertDebug(error == nil && keyPairCopy != nil);
    return keyPairCopy;
 }

--- a/README.md
+++ b/README.md
@ -1,4 +1,4 @@
-**Deprecation Warning**: It is recommended that [libsignal-protocol-c](https://github.com/whispersystems/libsignal-protocol-c) be used for all new applications.
+**Deprecation Warning**: It is recommended that the swift interface of [libsignal-client](https://github.com/signalapp/libsignal-client) be used for all new iOS applications. This library is no longer used by us or maintained.


 # SignalProtocolKit [![Build Status](https://travis-ci.org/WhisperSystems/AxolotlKit.svg?branch=master)](https://travis-ci.org/WhisperSystems/AxolotlKit)
Author	SHA1	Message	Date
Nora Trapp	06c654a757	Update README.md	2021-04-08 10:21:14 -07:00
Nora Trapp	36601e4bbe	Don't archive sessions when they are fresh.	2021-01-16 18:04:32 -08:00
Nora Trapp	9413e47751	Increase ratchet counter limit	2021-01-16 12:49:24 -08:00
Nora Trapp	c40a9fb072	Fix tests	2020-11-12 17:45:51 -08:00
Nora Trapp	18a7031342	Merge branch 'nt/fix-missing-session-issues'	2020-11-12 17:27:02 -08:00
Nora Trapp	43aa55e6be	PR Feedback	2020-11-12 17:26:50 -08:00
Nora Trapp	89c447b636	Add additional logging for decryption errors	2020-11-12 17:24:46 -08:00
Nora Trapp	170acafbc8	Only check identity key changes if our current session state has an identity key	2020-11-12 17:24:46 -08:00
Nora Trapp	99d700a87c	Don't purge previous session states after identity key change or promote previous session states after decryption.	2020-11-12 17:23:49 -08:00
Matthew Chen	582ec1a96c	Merge branch 'charlesmchen/sessionLogging'	2020-11-12 17:20:55 -03:00
Matthew Chen	8f8d565412	Improve logging around sessions.	2020-11-11 10:19:51 -03:00
Matthew Chen	0516a98a55	Merge branch 'charlesmchen/missingEphemeralPrekey'	2020-10-23 18:45:10 -03:00
Matthew Chen	f0632b87bb	Improve logging around missing ephemeral prekeys.	2020-10-23 16:09:52 -03:00
Matthew Chen	97ae15634e	Merge branch 'charlesmchen/prekeyLifecycle'	2020-08-25 21:24:50 -03:00
Matthew Chen	34073098e9	Use protocol contexts in prekey stores.	2020-08-25 20:27:11 -03:00
Matthew Chen	61ce278894	Use protocol contexts in prekey stores.	2020-08-25 20:19:43 -03:00
Matthew Chen	852d43fe8d	Use protocol contexts in prekey stores.	2020-08-25 20:08:38 -03:00
Michael Kirk	debc5cb311	Merge branch 'mkirk/compiler-warnings'	2020-03-09 16:49:17 -06:00
Michael Kirk	6a1c548be0	fix compiler warnings: missing nullability annotations	2019-12-16 17:47:16 -08:00
Matthew Chen	97bc4ea101	Merge branch 'charlesmchen/fixBrokenTests'	2019-11-07 17:19:02 -03:00
Matthew Chen	ddcdbd04da	Fix broken tests.	2019-11-07 13:27:48 -03:00
Matthew Chen	905c5d0e0c	Merge branch 'charlesmchen/prekeyManagement'	2019-11-02 08:14:31 -03:00
Matthew Chen	fb8ca529ae	Delete old and unused one-time prekeys. Thanks Mikunj Varsani for the bug report.	2019-11-01 12:54:06 -03:00
Nora Trapp	4a4899ea14	Merge branch 'nt/deployment-target'	2019-09-23 16:52:14 -07:00
Nora Trapp	1c5425eb26	Update deployment target to iOS 10	2019-09-23 10:46:21 -07:00
Michael Kirk	8d4451262d	Merge branch 'mkirk/missing-nullability-macros'	2019-06-19 10:08:44 -06:00
Michael Kirk	832cb97c95	add missing nullability macros	2019-06-19 10:08:32 -06:00
Michael Kirk	9bdcbaade2	Merge branch 'mkirk/typed-protocol-context'	2019-05-22 14:57:45 -04:00
Michael Kirk	d1739b2669	Apply ReadContext	2019-05-22 12:00:19 -04:00
Michael Kirk	3fe60a30fe	rename ProtocolContext -> SPKProtocolWriteContext	2019-05-22 10:50:45 -04:00
Matthew Chen	41c6a84b46	Add ProtocolContext Protocol.	2019-05-22 10:40:09 -04:00
Michael Kirk	aa4b0a7bfa	Merge branch 'mkirk/no-throws-on-load'	2019-05-21 11:08:55 -04:00
Michael Kirk	f852496e31	Move throw from loadPreKey protocol to AxolotlKit	2019-05-13 15:42:21 -06:00
Michael Kirk	dedb0f987a	Merge branch 'mkirk/fixup-tests'	2018-11-12 09:21:02 -06:00