AuroraMiddleware/libtomcrypt
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add copy_or_zeromem()

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This commit is contained in:
Steffen Jaeckel 2017-10-25 15:30:05 +02:00
parent c0b7c8dd67
commit 5c0b1b4bf6
3 changed files with 65 additions and 23 deletions
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24
src/encauth/ccm/ccm_memory.c
View File

@ -51,10 +51,6 @@ int ccm_memory(int cipher,
symmetric_key *skey;
int err;
unsigned long len, L, x, y, z, CTRlen;
#ifdef LTC_FAST
LTC_FAST_TYPE fastMask = ~0; /* initialize fastMask at all zeroes */
#endif
unsigned char mask = 0xff; /* initialize mask at all zeroes */
if (uskey == NULL) {
LTC_ARGCHK(key != NULL);
@ -360,29 +356,11 @@ int ccm_memory(int cipher,
/* Zero the plaintext if the tag was invalid (in constant time) */
if (ptlen > 0) {
y = 0;
mask *= 1 - err; /* mask = ( err ? 0 : 0xff ) */
#ifdef LTC_FAST
fastMask *= 1 - err;
if (ptlen & ~15) {
for (; y < (ptlen & ~15); y += 16) {
for (z = 0; z < 16; z += sizeof(LTC_FAST_TYPE)) {
*(LTC_FAST_TYPE_PTR_CAST(&pt_real[y+z])) = *(LTC_FAST_TYPE_PTR_CAST(&pt[y+z])) & fastMask;
}
}
}
#endif
for (; y < ptlen; y++) {
pt_real[y] = pt[y] & mask;
}
copy_or_zeromem(pt, pt_real, ptlen, err);
}
}
#ifdef LTC_CLEAN_STACK
#ifdef LTC_FAST
fastMask = 0;
#endif
mask = 0;
zeromem(PAD, sizeof(PAD));
zeromem(CTRPAD, sizeof(CTRPAD));
if (pt_work != NULL) {

3
src/headers/tomcrypt_misc.h
View File

@ -72,6 +72,9 @@ int hkdf(int hash_idx,
/* ---- MEM routines ---- */
int mem_neq(const void *a, const void *b, size_t len);
void zeromem(volatile void *dst, size_t len);
#ifdef LTC_SOURCE
void copy_or_zeromem(const unsigned char* src, unsigned char* dest, unsigned long len, int coz);
#endif
void burn_stack(unsigned long len);
const char *error_to_string(int err);

61
src/misc/copy_or_zeromem.c Normal file
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@ -0,0 +1,61 @@
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*/
#include "tomcrypt.h"
/**
@file copy_or_zeromem.c
Either copy or zero a block of memory in constant time, Steffen Jaeckel
*/
/**
Either copy or zero a block of memory in constant time
@param src The source where to read from
@param dest The destination where to write to
@param len The length of the area to process (octets)
@param coz Copy (on 0) Or Zero (> 0)
*/
void copy_or_zeromem(const unsigned char* src, unsigned char* dest, unsigned long len, int coz)
{
unsigned long y;
#ifdef LTC_FAST
unsigned long z;
LTC_FAST_TYPE fastMask = ~0; /* initialize fastMask at all ones */
#endif
unsigned char mask = 0xff; /* initialize mask at all ones */
LTC_ARGCHK(src != NULL);
LTC_ARGCHK(dest != NULL);
if (coz != 0) coz = 1;
y = 0;
mask *= 1 - coz; /* mask = ( coz ? 0 : 0xff ) */
#ifdef LTC_FAST
fastMask *= 1 - coz;
if (len & ~15) {
for (; y < (len & ~15); y += 16) {
for (z = 0; z < 16; z += sizeof(LTC_FAST_TYPE)) {
*(LTC_FAST_TYPE_PTR_CAST(&dest[y+z])) = *(LTC_FAST_TYPE_PTR_CAST(&src[y+z])) & fastMask;
}
}
}
#endif
for (; y < len; y++) {
dest[y] = src[y] & mask;
}
#ifdef LTC_CLEAN_STACK
#ifdef LTC_FAST
fastMask = 0;
#endif
mask = 0;
#endif
}
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */