68 lines
2.1 KiB
Objective-C
68 lines
2.1 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 "TSDerivedSecrets.h"
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#import <Curve25519Kit/Curve25519.h>
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#import <SignalCoreKit/OWSAsserts.h>
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#import <HKDFKit/HKDFKit.h>
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@implementation TSDerivedSecrets
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+ (instancetype)throws_derivedSecretsWithSeed:(NSData *)masterKey salt:(NSData *)salt info:(NSData *)info
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{
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OWSAssert(masterKey.length == 32);
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OWSAssert(info);
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TSDerivedSecrets *secrets = [[TSDerivedSecrets alloc] init];
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OWSAssert(secrets);
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if (!salt) {
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const char *HKDFDefaultSalt[4] = {0};
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salt = [NSData dataWithBytes:HKDFDefaultSalt length:sizeof(HKDFDefaultSalt)];
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}
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@try {
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NSData *derivedMaterial = [HKDFKit deriveKey:masterKey info:info salt:salt outputSize:96];
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secrets.cipherKey = [derivedMaterial subdataWithRange:NSMakeRange(0, 32)];
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secrets.macKey = [derivedMaterial subdataWithRange:NSMakeRange(32, 32)];
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secrets.iv = [derivedMaterial subdataWithRange:NSMakeRange(64, 16)];
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}
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@catch (NSException *exception) {
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@throw NSInvalidArgumentException;
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}
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OWSAssert(secrets.cipherKey.length == 32);
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OWSAssert(secrets.macKey.length == 32);
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OWSAssert(secrets.iv.length == 16);
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return secrets;
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}
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+ (instancetype)throws_derivedInitialSecretsWithMasterKey:(NSData *)masterKey
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{
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OWSAssert(masterKey);
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NSData *info = [@"WhisperText" dataUsingEncoding:NSUTF8StringEncoding];
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return [self throws_derivedSecretsWithSeed:masterKey salt:nil info:info];
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}
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+ (instancetype)throws_derivedRatchetedSecretsWithSharedSecret:(NSData *)masterKey rootKey:(NSData *)rootKey
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{
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OWSAssert(masterKey);
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OWSAssert(rootKey);
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NSData *info = [@"WhisperRatchet" dataUsingEncoding:NSUTF8StringEncoding];
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return [self throws_derivedSecretsWithSeed:masterKey salt:rootKey info:info];
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}
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+ (instancetype)throws_derivedMessageKeysWithData:(NSData *)data
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{
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OWSAssert(data);
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NSData *info = [@"WhisperMessageKeys" dataUsingEncoding:NSUTF8StringEncoding];
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return [self throws_derivedSecretsWithSeed:data salt:nil info:info];
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}
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@end
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