Bitcoin ABC  0.24.7
P2P Digital Currency
cleanse.cpp
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1 // Copyright (c) 2009-2010 Satoshi Nakamoto
2 // Copyright (c) 2009-2015 The Bitcoin Core developers
3 // Distributed under the MIT software license, see the accompanying
4 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
5 
6 #include <support/cleanse.h>
7 
8 #include <cstring>
9 
10 #if defined(_MSC_VER)
11 #include <Windows.h> // For SecureZeroMemory.
12 #endif
13 
14 void memory_cleanse(void *ptr, size_t len) {
15 #if defined(_MSC_VER)
16  /* SecureZeroMemory is guaranteed not to be optimized out by MSVC. */
17  SecureZeroMemory(ptr, len);
18 #else
19  std::memset(ptr, 0, len);
20 
21  /*
22  * Memory barrier that scares the compiler away from optimizing out the
23  * memset.
24  *
25  * Quoting Adam Langley <agl@google.com> in commit
26  * ad1907fe73334d6c696c8539646c21b11178f20f in BoringSSL (ISC License):
27  * As best as we can tell, this is sufficient to break any optimisations
28  * that might try to eliminate "superfluous" memsets.
29  * This method is used in memzero_explicit() the Linux kernel, too. Its
30  * advantage is that it is pretty efficient because the compiler can still
31  * implement the memset() efficiently, just not remove it entirely. See
32  * "Dead Store Elimination (Still) Considered Harmful" by Yang et al.
33  * (USENIX Security 2017) for more background.
34  */
35  __asm__ __volatile__("" : : "r"(ptr) : "memory");
36 #endif
37 }
memory_cleanse
void memory_cleanse(void *ptr, size_t len)
Secure overwrite a buffer (possibly containing secret data) with zero-bytes.
Definition: cleanse.cpp:14
cleanse.h