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Merge pull request #8114 from cladmi/pr/crypto/ccm/auth_data_len_upper_bound

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crypto/ccm: fix auth_data_len check
This commit is contained in:
Koen Zandberg 2018-11-12 17:30:17 +01:00 committed by GitHub
commit 00b6e46abc
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2 changed files with 18 additions and 4 deletions
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18
sys/crypto/modes/ccm.c
View File

@ -108,13 +108,17 @@ int ccm_compute_adata_mac(cipher_t* cipher, uint8_t* auth_data,
/* 16 octet block size + max. 10 len encoding */
uint8_t auth_data_encoded[26], len_encoding = 0;
if ( auth_data_len < (((uint32_t) 2) << 16)) { /* length (0x0001 ... 0xFEFF) */
/* If 0 < l(a) < (2^16 - 2^8), then the length field is encoded as two
* octets. (RFC3610 page 2)
*/
if (auth_data_len <= 0xFEFF) {
/* length (0x0001 ... 0xFEFF) */
len_encoding = 2;
auth_data_encoded[1] = auth_data_len & 0xFF;
auth_data_encoded[0] = (auth_data_len >> 8) & 0xFF;
} else {
DEBUG("UNSUPPORTED Adata length\n");
DEBUG("UNSUPPORTED Adata length: %" PRIu32 "\n", auth_data_len);
return -1;
}
@ -167,7 +171,10 @@ int cipher_encrypt_ccm(cipher_t* cipher, uint8_t* auth_data, uint32_t auth_data_
}
/* MAC calulation (T) with additional data and plaintext */
ccm_compute_adata_mac(cipher, auth_data, auth_data_len, mac_iv);
len = ccm_compute_adata_mac(cipher, auth_data, auth_data_len, mac_iv);
if (len < 0) {
return len;
}
len = ccm_compute_cbc_mac(cipher, mac_iv, input, input_len, mac);
if (len < 0) {
return len;
@ -245,7 +252,10 @@ int cipher_decrypt_ccm(cipher_t* cipher, uint8_t* auth_data,
}
/* MAC calulation (T) with additional data and plaintext */
ccm_compute_adata_mac(cipher, auth_data, auth_data_len, mac_iv);
len = ccm_compute_adata_mac(cipher, auth_data, auth_data_len, mac_iv);
if (len < 0) {
return len;
}
len = ccm_compute_cbc_mac(cipher, mac_iv, plain, plain_len, mac);
if (len < 0) {
return len;

4
tests/unittests/tests-crypto/tests-crypto-modes-ccm.c
View File

@ -246,6 +246,10 @@ static void test_crypto_modes_ccm_check_len(void)
ret = _test_ccm_len(cipher_decrypt_ccm, 8, einput, 16, 0);
TEST_ASSERT_MESSAGE(ret > 0, "Decryption : failed with valid input_len");
/* ccm library does not support auth_data_len > 0xFEFF */
ret = _test_ccm_len(cipher_encrypt_ccm, 2, NULL, 0, 0xFEFF + 1);
TEST_ASSERT_EQUAL_INT(-1, ret);
}