If you are referring to the decrypting Visa Checkout Consumer information with C#, below is a C# Decryption Example:
using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
class Decrypt {
const int HMAC_LENGTH = 32, IV_LENGTH = 16;
public static String decryptPayload(String key, String wrappedKey, String payload) {
return Encoding.UTF8.GetString(decrypt(decrypt(Encoding.UTF8.GetBytes(key),
Convert.FromBase64String(wrappedKey)), Convert.FromBase64String(payload)));
}
public static byte[] decrypt(byte[] key, byte[] data) {
if (data == null || data.Length <= IV_LENGTH + HMAC_LENGTH) {
throw new ArgumentException("Bad input data", "data");
}
byte[] hmac = new byte[HMAC_LENGTH];
Array.Copy(data, 0, hmac, 0, HMAC_LENGTH);
byte[] iv = new byte[IV_LENGTH];
Array.Copy(data, HMAC_LENGTH, iv, 0, IV_LENGTH);
byte[] payload = new byte[data.Length - HMAC_LENGTH - IV_LENGTH];
Array.Copy(data, HMAC_LENGTH + IV_LENGTH, payload, 0, payload.Length);
//if (byteArrayEquals(hmac, dohmac(key, byteArrayConcat(iv, payload)))) {
// TODO: Handle HMAC validation failure
//}
Aes aes = new AesManaged();
aes.BlockSize = 128;
aes.KeySize = 256;
aes.Key = hash(key);
aes.IV = iv;
aes.Mode = CipherMode.CBC;
aes.Padding = PaddingMode.PKCS7;
MemoryStream ms = new MemoryStream();
CryptoStream cs=new CryptoStream(ms,aes.CreateDecryptor(),CryptoStreamMode.Write);
cs.Write(payload, 0, payload.Length);
cs.FlushFinalBlock();
return ms.ToArray();
}
public static byte[] hash(byte[] key) {
return (new SHA256Managed()).ComputeHash(key);
}
public static byte[] dohmac(byte[] key, byte[] data) {
return (new HMACSHA256(key)).ComputeHash(data);
}
public static void Main(string[] args) {
Console.WriteLine(decryptPayload("SECRET_KEY", "..."));
}
}
