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56 lines
1.3 KiB
Objective-C
56 lines
1.3 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 "NSData+OWS.h"
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NS_ASSUME_NONNULL_BEGIN
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@implementation NSData (OWS)
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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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- (NSData *)dataByAppendingData:(NSData *)data
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{
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NSMutableData *result = [self mutableCopy];
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[result appendData:data];
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return [result copy];
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}
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- (NSString *)hexadecimalString
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{
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/* Returns hexadecimal string of NSData. Empty string if data is empty. */
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const unsigned char *dataBuffer = (const unsigned char *)[self bytes];
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if (!dataBuffer) {
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return @"";
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}
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NSUInteger dataLength = [self length];
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NSMutableString *hexString = [NSMutableString stringWithCapacity:(dataLength * 2)];
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for (NSUInteger i = 0; i < dataLength; ++i) {
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[hexString appendFormat:@"%02x", dataBuffer[i]];
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}
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return [hexString copy];
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}
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@end
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NS_ASSUME_NONNULL_END
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