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stream/chacha - improved counter increment

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This commit is contained in:
Karel Miko 2017-04-25 17:21:35 +02:00
parent 9232f2e970
commit 90b482aa1e
1 changed files with 8 additions and 2 deletions
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10
src/stream/chacha/chacha_crypt.c
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@ -71,8 +71,14 @@ int chacha_crypt(chacha_state *st, const unsigned char *in, unsigned long inlen,
} }
for (;;) { for (;;) {
_chacha_block(buf, st->input, st->rounds); _chacha_block(buf, st->input, st->rounds);
/* increment the counter */ if (st->ivlen == 8) {
if (!++st->input[12] && !++st->input[13] && !++st->input[14]) { ++st->input[15]; } /* IV-64bit, increment 64bit counter */
if (0 == ++st->input[12] && 0 == ++st->input[13]) return CRYPT_OVERFLOW;
}
else {
/* IV-96bit, increment 32bit counter */
if (0 == ++st->input[12]) return CRYPT_OVERFLOW;
}
if (inlen <= 64) { if (inlen <= 64) {
for (i = 0; i < inlen; ++i) out[i] = in[i] ^ buf[i]; for (i = 0; i < inlen; ++i) out[i] = in[i] ^ buf[i];
st->ksleft = 64 - inlen; st->ksleft = 64 - inlen;