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Constant-time hex2bin.

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This commit is contained in:
Frank Denis 2015-02-10 17:01:51 +01:00
parent 2fb83ade4c
commit f8af1790dd
1 changed files with 12 additions and 9 deletions
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21
src/libsodium/sodium/utils.c
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@ -131,22 +131,25 @@ sodium_hex2bin(unsigned char * const bin, const size_t bin_maxlen,
int ret = 0;
unsigned char c;
unsigned char c_acc = 0U;
unsigned char c_num;
unsigned char c_alpha0, c_alpha;
unsigned char c_num0, c_num;
unsigned char c_val;
unsigned char state = 0U;
while (hex_pos < hex_len) {
c = (unsigned char) hex[hex_pos];
if ((c_num = c ^ 48U) < 10U) {
c_val = c_num;
} else if ((c_num = (c & ~32U)) > 64 && c_num < 71U) {
c_val = c_num - 55U;
} else if (ignore != NULL && strchr(ignore, c) != NULL && state == 0U) {
hex_pos++;
continue;
} else {
c_num = c ^ 48U;
c_num0 = (c_num - 10U) >> 8;
c_alpha = (c & ~32U) - 55U;
c_alpha0 = ((c_alpha - 10U) ^ (c_alpha - 16U)) >> 8;
if ((c_num0 | c_alpha0) == 0U) {
if (ignore != NULL && state == 0U && strchr(ignore, c) != NULL) {
hex_pos++;
continue;
}
break;
}
c_val = (c_num0 & c_num) | (c_alpha0 & c_alpha);
if (bin_pos >= bin_maxlen) {
ret = -1;
errno = ERANGE;