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Fix SM4-CCM counter overflow bug

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Need test vectors to check the correctness
This commit is contained in:
Zhi Guan
2024-04-22 17:43:29 +08:00
parent e05fd9c1b9
commit ae2f635b7f
1 changed files with 28 additions and 4 deletions
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32
src/sm4_ccm.c
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@@ -14,8 +14,6 @@
#include <gmssl/error.h>
static void length_to_bytes(size_t len, size_t nbytes, uint8_t *out)
{
uint8_t *p = out + nbytes - 1;
@@ -25,6 +23,32 @@ static void length_to_bytes(size_t len, size_t nbytes, uint8_t *out)
}
}
static void ctr_n_incr(uint8_t a[16], size_t n)
{
size_t i;
for (i = 15; i >= 16 - n; i--) {
a[i]++;
if (a[i]) break;
}
}
// TODO: add test vectors for counter overflow
static void sm4_ctr_n_encrypt(const SM4_KEY *key, uint8_t ctr[16], size_t n, const uint8_t *in, size_t inlen, uint8_t *out)
{
uint8_t block[16];
size_t len;
while (inlen) {
len = inlen < 16 ? inlen : 16;
sm4_encrypt(key, ctr, block);
gmssl_memxor(out, in, block, len);
ctr_n_incr(ctr, n);
in += len;
out += len;
inlen -= len;
}
}
int sm4_ccm_encrypt(const SM4_KEY *sm4_key, const uint8_t *iv, size_t ivlen,
const uint8_t *aad, size_t aadlen, const uint8_t *in, size_t inlen,
uint8_t *out, size_t taglen, uint8_t *tag)
@@ -97,7 +121,7 @@ int sm4_ccm_encrypt(const SM4_KEY *sm4_key, const uint8_t *iv, size_t ivlen,
sm4_encrypt(sm4_key, ctr, block);
ctr[15] = 1;
sm4_ctr_encrypt(sm4_key, ctr, in, inlen, out);
sm4_ctr_n_encrypt(sm4_key, ctr, 15 - ivlen, in, inlen, out);
sm4_cbc_mac_update(&mac_ctx, in, inlen);
if (inlen % 16) {
@@ -182,7 +206,7 @@ int sm4_ccm_decrypt(const SM4_KEY *sm4_key, const uint8_t *iv, size_t ivlen,
sm4_encrypt(sm4_key, ctr, block);
ctr[15] = 1;
sm4_ctr_encrypt(sm4_key, ctr, in, inlen, out);
sm4_ctr_n_encrypt(sm4_key, ctr, 15 - ivlen, in, inlen, out);
sm4_cbc_mac_update(&mac_ctx, out, inlen); // diff from encrypt
if (inlen % 16) {