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sys/crypto: Allow CCM encryption with AAD of length > 24

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Fixes parts of issue #8107
This commit is contained in:
Mathias Tausig 2020-01-07 21:25:06 +01:00
parent f266275afb
commit 6fe6f8f6ca
1 changed files with 25 additions and 4 deletions
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29
sys/crypto/modes/ccm.c
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@ -105,8 +105,8 @@ static int ccm_compute_adata_mac(cipher_t *cipher, const uint8_t *auth_data,
if (auth_data_len > 0) {
int len;
/* 16 octet block size + max. 10 len encoding */
uint8_t auth_data_encoded[26], len_encoding = 0;
/* Create a block with the encoded length. Block length is always 16 */
uint8_t auth_data_encoded[CCM_BLOCK_SIZE], len_encoding = 0;
/* If 0 < l(a) < (2^16 - 2^8), then the length field is encoded as two
* octets. (RFC3610 page 2)
@ -123,12 +123,32 @@ static int ccm_compute_adata_mac(cipher_t *cipher, const uint8_t *auth_data,
return -1;
}
memcpy(auth_data_encoded + len_encoding, auth_data, auth_data_len);
uint8_t auth_data_len_in_encoded =
(auth_data_len >=
(uint32_t)CCM_BLOCK_SIZE -
len_encoding) ? ((uint32_t)CCM_BLOCK_SIZE -
len_encoding) :
auth_data_len;
memcpy(auth_data_encoded + len_encoding, auth_data,
auth_data_len_in_encoded);
/* Calculate the MAC over the first block of AAD + heading length encoding */
len = ccm_compute_cbc_mac(cipher, X1, auth_data_encoded,
auth_data_len + len_encoding, X1);
auth_data_len_in_encoded + len_encoding, X1);
if (len < 0) {
return -1;
}
/* Calculate the MAC for the remainder of the AAD (if there is one) */
if (auth_data_len_in_encoded < auth_data_len) {
len = ccm_compute_cbc_mac(cipher, X1,
auth_data + auth_data_len_in_encoded,
auth_data_len - auth_data_len_in_encoded,
X1);
if (len < 0) {
return -1;
}
}
}
return 0;
@ -180,6 +200,7 @@ int cipher_encrypt_ccm(cipher_t *cipher,
if (len < 0) {
return len;
}
len = ccm_compute_cbc_mac(cipher, mac_iv, input, input_len, mac);
if (len < 0) {
return len;