Aes_ecb_encryptor::Aes_ecb_encryptor (const unsigned char* raw_key)
: impl(new Aes_impl)
{
if (AES_set_encrypt_key(raw_key, KEY_LEN * 8, &(impl->key)) != 0) {
throw Crypto_error("Aes_ctr_encryptor::Aes_ctr_encryptor", "AES_set_encrypt_key failed");
}
}
Aes_ctr_encryptor::Aes_ctr_encryptor (const unsigned char* raw_key, const unsigned char* arg_nonce)
{
if (AES_set_encrypt_key(raw_key, KEY_LEN * 8, &key) != 0) {
throw Crypto_error("Aes_ctr_encryptor::Aes_ctr_encryptor", "AES_set_encrypt_key failed");
}
std::memcpy(nonce, arg_nonce, NONCE_LEN);
byte_counter = 0;
std::memset(otp, '\0', sizeof(otp));
}
void random_bytes (unsigned char* buffer, size_t len)
{
if (RAND_bytes(buffer, len) != 1) {
std::ostringstream message;
while (unsigned long code = ERR_get_error()) {
char error_string[120];
ERR_error_string_n(code, error_string, sizeof(error_string));
message << "OpenSSL Error: " << error_string << "; ";
}
throw Crypto_error("random_bytes", message.str());
}
}
void Aes_ctr_encryptor::process (const unsigned char* in, unsigned char* out, size_t len)
{
for (size_t i = 0; i < len; ++i) {
if (byte_counter % BLOCK_LEN == 0) {
unsigned char ctr[BLOCK_LEN];
// First 12 bytes of CTR: nonce
std::memcpy(ctr, nonce, NONCE_LEN);
// Last 4 bytes of CTR: block number (sequentially increasing with each block) (big endian)
store_be32(ctr + NONCE_LEN, byte_counter / BLOCK_LEN);
// Generate a new OTP
AES_encrypt(ctr, otp, &key);
}
// encrypt one byte
out[i] = in[i] ^ otp[byte_counter++ % BLOCK_LEN];
if (byte_counter == 0) {
throw Crypto_error("Aes_ctr_encryptor::process", "Too much data to encrypt securely");
}
}
}
