112 lines
4.1 KiB
Objective-C
112 lines
4.1 KiB
Objective-C
//
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// Copyright (c) 2018 Open Whisper Systems. All rights reserved.
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//
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#import "OWSVerificationStateSyncMessage.h"
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#import "Cryptography.h"
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#import "OWSIdentityManager.h"
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#import <SignalServiceKit/SignalServiceKit-Swift.h>
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NS_ASSUME_NONNULL_BEGIN
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#pragma mark -
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@interface OWSVerificationStateSyncMessage ()
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@property (nonatomic, readonly) OWSVerificationState verificationState;
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@property (nonatomic, readonly) NSData *identityKey;
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@end
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#pragma mark -
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@implementation OWSVerificationStateSyncMessage
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- (instancetype)initWithVerificationState:(OWSVerificationState)verificationState
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identityKey:(NSData *)identityKey
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verificationForRecipientId:(NSString *)verificationForRecipientId
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{
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OWSAssert(identityKey.length == kIdentityKeyLength);
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OWSAssert(verificationForRecipientId.length > 0);
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// we only sync user's marking as un/verified. Never sync the conflicted state, the sibling device
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// will figure that out on it's own.
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OWSAssert(verificationState != OWSVerificationStateNoLongerVerified);
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self = [super init];
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if (!self) {
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return self;
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}
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_verificationState = verificationState;
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_identityKey = identityKey;
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_verificationForRecipientId = verificationForRecipientId;
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// This sync message should be 1-512 bytes longer than the corresponding NullMessage
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// we store this values so the corresponding NullMessage can subtract it from the total length.
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_paddingBytesLength = arc4random_uniform(512) + 1;
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return self;
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}
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- (nullable instancetype)initWithCoder:(NSCoder *)coder
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{
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return [super initWithCoder:coder];
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}
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- (nullable SSKProtoSyncMessageBuilder *)syncMessageBuilder
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{
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OWSAssert(self.identityKey.length == kIdentityKeyLength);
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OWSAssert(self.verificationForRecipientId.length > 0);
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// we only sync user's marking as un/verified. Never sync the conflicted state, the sibling device
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// will figure that out on it's own.
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OWSAssert(self.verificationState != OWSVerificationStateNoLongerVerified);
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SSKProtoVerifiedBuilder *verifiedBuilder = [SSKProtoVerifiedBuilder new];
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verifiedBuilder.destination = self.verificationForRecipientId;
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verifiedBuilder.identityKey = self.identityKey;
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verifiedBuilder.state = OWSVerificationStateToProtoState(self.verificationState);
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OWSAssert(self.paddingBytesLength != 0);
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// We add the same amount of padding in the VerificationStateSync message and it's coresponding NullMessage so that
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// the sync message is indistinguishable from an outgoing Sent transcript corresponding to the NullMessage. We pad
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// the NullMessage so as to obscure it's content. The sync message (like all sync messages) will be *additionally*
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// padded by the superclass while being sent. The end result is we send a NullMessage of a non-distinct size, and a
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// verification sync which is ~1-512 bytes larger then that.
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verifiedBuilder.nullMessage = [Cryptography generateRandomBytes:self.paddingBytesLength];
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NSError *error;
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SSKProtoVerified *_Nullable verifiedProto = [verifiedBuilder buildAndReturnError:&error];
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if (error || !verifiedProto) {
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OWSFail(@"%@ could not build protobuf: %@", self.logTag, error);
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return nil;
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}
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SSKProtoSyncMessageBuilder *syncMessageBuilder = [SSKProtoSyncMessageBuilder new];
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[syncMessageBuilder setVerified:verifiedProto];
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return syncMessageBuilder;
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}
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- (size_t)unpaddedVerifiedLength
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{
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OWSAssert(self.identityKey.length == kIdentityKeyLength);
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OWSAssert(self.verificationForRecipientId.length > 0);
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// we only sync user's marking as un/verified. Never sync the conflicted state, the sibling device
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// will figure that out on it's own.
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OWSAssert(self.verificationState != OWSVerificationStateNoLongerVerified);
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SSKProtoVerifiedBuilder *verifiedBuilder = [SSKProtoVerifiedBuilder new];
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verifiedBuilder.destination = self.verificationForRecipientId;
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verifiedBuilder.identityKey = self.identityKey;
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verifiedBuilder.state = OWSVerificationStateToProtoState(self.verificationState);
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return [verifiedBuilder build].data.length;
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}
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@end
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NS_ASSUME_NONNULL_END
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