void AesCounter::encrypt(const unsigned char *datain, unsigned char *dataout, int len, std::uint64_t sequenceNumber)
{
memset(ctr_buf, 0, DREL_AES_BLOCKLEN_BYTES);
if (len <= 0 || len > DREL_AES_MAXPACKETOCT) throw AesException("Invalid input plaintext message length");
if (sequenceNumber == 0xFFFFFFFFFFFFFFFF) throw AesException("Packet counter exceeded - IV");
// Copy secretIV to counter buffer
memcpy(ctr_buf, mSecretIV, DREL_AESCOUNTER_SECRETIVLEN);
// Copy packet sequence number to counter buffer
std::uint64_t beSequencenumber = San2::Utils::Endian::san_s_be64toh(sequenceNumber);
memcpy(ctr_buf + DREL_AESCOUNTER_SECRETIVLEN, &beSequencenumber, sizeof(std::uint64_t));
// Set blockCounter to one
std::uint16_t blockCounter = 1;
blockCounter = San2::Utils::Endian::san_u_htobe16(blockCounter);
memcpy(ctr_buf + DREL_AESCOUNTER_SECRETIVLEN + sizeof(std::uint64_t), &blockCounter, sizeof(std::uint16_t));
//aes_mode_reset(aes_ctx); // important!!! do not delete!!!
if (aes_encrypt_key256(mKey, aes_ctx) != EXIT_SUCCESS) throw AesException("Key setup failed");
int ret = aes_ctr_crypt(datain, dataout, len, ctr_buf, aes_custom_inc, aes_ctx);
if (ret != EXIT_SUCCESS) throw AesException("Aes encryption failed");
}
int main(int argc, char *argv[])
{
unsigned char encrypted[sizeof(message)];
unsigned char decrypted[sizeof(message)];
unsigned char nonce[] = { 0xde, 0xea, 0xbe, 0xef, 'd', 'e', 'a', 'd' };
memcpy(decrypted, message, sizeof(message));
aes_ctr_crypt(decrypted, encrypted, sizeof(message), key_size * 8, key,
nonce, true);
memset(decrypted, 0, sizeof(message));
aes_ctr_crypt(encrypted, decrypted, sizeof(message), key_size * 8, key,
nonce, true);
printf("%s", decrypted);
return 0;
}
int
BCMROMFN(aes_ccm_decrypt)(unsigned int *rk,
const size_t key_len,
const uint8 *nonce,
const size_t aad_len,
const uint8 *aad,
const size_t data_len,
const uint8 *ctxt,
uint8 *ptxt)
{
uint8 A[AES_BLOCK_SZ], X[AES_BLOCK_SZ];
/* initialize counter */
A[0] = AES_CCM_CRYPT_FLAGS;
memcpy(&A[1], nonce, AES_CCM_NONCE_LEN);
A[AES_BLOCK_SZ - 2] = 0;
A[AES_BLOCK_SZ - 1] = 1;
pres("aes_ccm_decrypt: initial counter:", AES_BLOCK_SZ, A);
/* decrypt data */
if (aes_ctr_crypt(rk, key_len, A, data_len-AES_CCM_AUTH_LEN, ctxt, ptxt))
return (-1);
pres("aes_ccm_decrypt: decrypted data:", data_len-AES_CCM_AUTH_LEN, ptxt);
/* decrypt MAC */
A[AES_BLOCK_SZ - 2] = 0;
A[AES_BLOCK_SZ - 1] = 0;
if (aes_ctr_crypt(rk, key_len, A, AES_CCM_AUTH_LEN,
ctxt+data_len-AES_CCM_AUTH_LEN, ptxt + data_len - AES_CCM_AUTH_LEN))
return (-1);
pres("aes_ccm_decrypt: decrypted MAC:", AES_CCM_AUTH_LEN,
ptxt + data_len - AES_CCM_AUTH_LEN);
/* calculate MAC */
if (aes_ccm_mac(rk, key_len, nonce, aad_len, aad,
data_len - AES_CCM_AUTH_LEN, ptxt, X))
return (-1);
pres("aes_ccm_decrypt: MAC:", AES_CCM_AUTH_LEN, X);
if (memcmp(X, ptxt + data_len - AES_CCM_AUTH_LEN, AES_CCM_AUTH_LEN) != 0)
return (-1);
return (0);
}
AES_RETURN rfc3686_crypt(const unsigned char *ibuf, unsigned char *obuf, int len,
unsigned char *cbuf, aes_encrypt_ctx cx[1])
{
return aes_ctr_crypt(ibuf, obuf, len, cbuf, rfc3686_inc, cx);
}