33 lines
746 B
Objective-C
33 lines
746 B
Objective-C
//
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// Copyright (c) 2017 Open Whisper Systems. All rights reserved.
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//
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#import "NSData+OWSConstantTimeCompare.h"
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NS_ASSUME_NONNULL_BEGIN
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@implementation NSData (OWSConstantTimeCompare)
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- (BOOL)ows_constantTimeIsEqualToData:(NSData *)other
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{
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volatile UInt8 isEqual = 0;
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if (self.length != other.length) {
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return NO;
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}
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UInt8 *leftBytes = (UInt8 *)self.bytes;
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UInt8 *rightBytes = (UInt8 *)other.bytes;
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for (int i = 0; i < self.length; i++) {
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// rather than returning as soon as we find a discrepency, we compare the rest of
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// the byte stream to maintain a constant time comparison
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isEqual |= leftBytes[i] ^ rightBytes[i];
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}
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return isEqual == 0;
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}
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@end
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NS_ASSUME_NONNULL_END
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