1*635a8641SAndroid Build Coastguard Worker // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2*635a8641SAndroid Build Coastguard Worker // Use of this source code is governed by a BSD-style license that can be 3*635a8641SAndroid Build Coastguard Worker // found in the LICENSE file. 4*635a8641SAndroid Build Coastguard Worker 5*635a8641SAndroid Build Coastguard Worker #ifndef CRYPTO_SECURE_UTIL_H_ 6*635a8641SAndroid Build Coastguard Worker #define CRYPTO_SECURE_UTIL_H_ 7*635a8641SAndroid Build Coastguard Worker 8*635a8641SAndroid Build Coastguard Worker #include <stddef.h> 9*635a8641SAndroid Build Coastguard Worker 10*635a8641SAndroid Build Coastguard Worker #include "crypto/crypto_export.h" 11*635a8641SAndroid Build Coastguard Worker 12*635a8641SAndroid Build Coastguard Worker namespace crypto { 13*635a8641SAndroid Build Coastguard Worker 14*635a8641SAndroid Build Coastguard Worker // Performs a constant-time comparison of two strings, returning true if the 15*635a8641SAndroid Build Coastguard Worker // strings are equal. 16*635a8641SAndroid Build Coastguard Worker // 17*635a8641SAndroid Build Coastguard Worker // For cryptographic operations, comparison functions such as memcmp() may 18*635a8641SAndroid Build Coastguard Worker // expose side-channel information about input, allowing an attacker to 19*635a8641SAndroid Build Coastguard Worker // perform timing analysis to determine what the expected bits should be. In 20*635a8641SAndroid Build Coastguard Worker // order to avoid such attacks, the comparison must execute in constant time, 21*635a8641SAndroid Build Coastguard Worker // so as to not to reveal to the attacker where the difference(s) are. 22*635a8641SAndroid Build Coastguard Worker // For an example attack, see 23*635a8641SAndroid Build Coastguard Worker // http://groups.google.com/group/keyczar-discuss/browse_thread/thread/5571eca0948b2a13 24*635a8641SAndroid Build Coastguard Worker CRYPTO_EXPORT bool SecureMemEqual(const void* s1, const void* s2, size_t n); 25*635a8641SAndroid Build Coastguard Worker 26*635a8641SAndroid Build Coastguard Worker } // namespace crypto 27*635a8641SAndroid Build Coastguard Worker 28*635a8641SAndroid Build Coastguard Worker #endif // CRYPTO_SECURE_UTIL_H_ 29*635a8641SAndroid Build Coastguard Worker 30