public byte[] DecryptAES256CBC4Msg(byte[] data)
{
//blocksize = OpenSSL.get_cipher(ciphername).get_blocksize()
const int blocksize = 16;
//iv = data[:blocksize]
//i = blocksize
int pos = 0;
var iv = data.ReadBytes(ref pos, blocksize);
//curve, pubkey_x, pubkey_y, i2 = ECC._decode_pubkey(data[i:])
//i += i2
UInt16 curve;
byte[] pubkeyX;
byte[] pubkeyY;
ECC._decode_pubkey(data, out curve, out pubkeyX, out pubkeyY, ref pos);
//ciphertext = data[i:len(data)-32]
//i += len(ciphertext)
var ciphertext = data.ReadBytes(ref pos, data.Length - pos - 32);
//mac = data[i:]
var mac = data.ReadBytes(ref pos, 32);
//key = sha512(self.raw_get_ecdh_key(pubkey_x, pubkey_y)).digest()
byte[] key;
using (var sha512 = new SHA512Managed())
key = sha512.ComputeHash(new ECC(null, null, null, null, Wif2PrivateKey(PrivEncryptionKeyWif), ECC.Secp256K1).raw_get_ecdh_key(pubkeyX, pubkeyY));
//key_e, key_m = key[:32], key[32:]
byte[] key_e = new byte[32];
byte[] key_m = new byte[32];
Buffer.BlockCopy(key, 0, key_e, 0, 32);
Buffer.BlockCopy(key, 32, key_m, 0, 32);
//if hmac_sha256(key_m, ciphertext) != mac:
// raise RuntimeError("Fail to verify data")
if (!new HMACSHA256(key_m).ComputeHash(ciphertext).SequenceEqual(mac))
throw new Exception("Fail to verify data");
var ctx = new Cipher(key_e, iv, false);
return ctx.Ciphering(ciphertext);
}
internal static byte[] Encrypt(byte[] data, byte[] pubkey)
{
// pyelliptic.ECC(curve='secp256k1').encrypt(msg,hexToPubkey(hexPubkey))
// curve, pubkey_x, pubkey_y, i = ECC._decode_pubkey(pubkey)
UInt16 curve = ECC.Secp256K1;
string ciphername = "aes-256-cbc";
var ephem = new ECC(null, null, null, null, null, curve);
byte[] pubkey_x = new byte[32];
byte[] pubkey_y = new byte[32];
Buffer.BlockCopy(pubkey, 1, pubkey_x, 0, 32);
Buffer.BlockCopy(pubkey, 33, pubkey_y, 0, 32);
//key = sha512(ephem.raw_get_ecdh_key(pubkey_x, pubkey_y)).digest()
byte[] key;
using (var sha512 = new SHA512Managed())
key = sha512.ComputeHash(ephem.raw_get_ecdh_key(pubkey_x, pubkey_y));
byte[] key_e = new byte[32];
byte[] key_m = new byte[32];
Buffer.BlockCopy(key, 0, key_e, 0, 32);
Buffer.BlockCopy(key, 32, key_m, 0, 32);
byte[] pubkey4Write = ephem.get_pubkey();
byte[] iv = new byte[get_blocksize("aes-256-cbc")];
using (var rnd = new RNGCryptoServiceProvider())
rnd.GetBytes(iv);
var ctx = new Cipher(key_e, iv, true, ciphername);
var ciphertext = ctx.Ciphering(data);
var mac = new HMACSHA256(key_m).ComputeHash(ciphertext);
byte[] result = new byte[iv.Length + pubkey4Write.Length + ciphertext.Length + mac.Length];
Buffer.BlockCopy(iv, 0, result, 0, iv.Length);
Buffer.BlockCopy(pubkey4Write, 0, result, iv.Length, pubkey4Write.Length);
Buffer.BlockCopy(ciphertext, 0, result, iv.Length + pubkey4Write.Length, ciphertext.Length);
Buffer.BlockCopy(mac, 0, result, iv.Length + pubkey4Write.Length + ciphertext.Length, mac.Length);
//Debug.WriteLine("iv=" + iv.ToHex());
//Debug.WriteLine("pubkey4Write=" + pubkey4Write.ToHex());
return result;
}
