void append(Blob& blob, const byte* buf, uint32_t len)
{
if (len != 0) {
assert(buf != 0);
Blob::size_type size = blob.size();
if (blob.capacity() - size < len) {
blob.reserve(size + 65536);
}
blob.resize(size + len);
std::memcpy(&blob[size], buf, len);
}
} // append
Blob encryptECIES (const openssl::ec_key& secretKey, const openssl::ec_key& publicKey, Blob const& plaintext)
{
ECIES_ENC_IV_TYPE iv;
random_fill (iv.begin (), ECIES_ENC_BLK_SIZE);
ECIES_ENC_KEY_TYPE secret;
ECIES_HMAC_KEY_TYPE hmacKey;
getECIESSecret (secretKey, publicKey, secret, hmacKey);
ECIES_HMAC_TYPE hmac = makeHMAC (hmacKey, plaintext);
hmacKey.zero ();
EVP_CIPHER_CTX ctx;
EVP_CIPHER_CTX_init (&ctx);
if (EVP_EncryptInit_ex (&ctx, ECIES_ENC_ALGO, nullptr, secret.begin (), iv.begin ()) != 1)
{
EVP_CIPHER_CTX_cleanup (&ctx);
secret.zero ();
throw std::runtime_error ("init cipher ctx");
}
secret.zero ();
Blob out (plaintext.size () + ECIES_HMAC_SIZE + ECIES_ENC_KEY_SIZE + ECIES_ENC_BLK_SIZE, 0);
int len = 0, bytesWritten;
// output IV
memcpy (& (out.front ()), iv.begin (), ECIES_ENC_BLK_SIZE);
len = ECIES_ENC_BLK_SIZE;
// Encrypt/output HMAC
bytesWritten = out.capacity () - len;
assert (bytesWritten > 0);
if (EVP_EncryptUpdate (&ctx, & (out.front ()) + len, &bytesWritten, hmac.begin (), ECIES_HMAC_SIZE) < 0)
{
EVP_CIPHER_CTX_cleanup (&ctx);
throw std::runtime_error ("");
}
len += bytesWritten;
// encrypt/output plaintext
bytesWritten = out.capacity () - len;
assert (bytesWritten > 0);
if (EVP_EncryptUpdate (&ctx, & (out.front ()) + len, &bytesWritten, & (plaintext.front ()), plaintext.size ()) < 0)
{
EVP_CIPHER_CTX_cleanup (&ctx);
throw std::runtime_error ("");
}
len += bytesWritten;
// finalize
bytesWritten = out.capacity () - len;
if (EVP_EncryptFinal_ex (&ctx, & (out.front ()) + len, &bytesWritten) < 0)
{
EVP_CIPHER_CTX_cleanup (&ctx);
throw std::runtime_error ("encryption error");
}
len += bytesWritten;
// Output contains: IV, encrypted HMAC, encrypted data, encrypted padding
assert (len <= (plaintext.size () + ECIES_HMAC_SIZE + (2 * ECIES_ENC_BLK_SIZE)));
assert (len >= (plaintext.size () + ECIES_HMAC_SIZE + ECIES_ENC_BLK_SIZE)); // IV, HMAC, data
out.resize (len);
EVP_CIPHER_CTX_cleanup (&ctx);
return out;
}