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A sample C# class to encrypt and decrypt texts using the cipher AES-256-CBC used in Laravel.
using System;
using System.Text;
using System.Security.Cryptography;
using System.Web.Script.Serialization;
using System.Collections.Generic;
namespace Aes256CbcEncrypterApp
{
class MainClass
{
public static void Main(string[] args)
{
Console.WriteLine("Hello, world!");
// The sample encryption key. Must be 32 characters.
string Key = "8UHjPgXZzXCGkhxV2QCnooyJexUzvJrO";
// The sample text to encrypt and decrypt.
string Text = "Here is some text to encrypt!";
// Encrypt and decrypt the sample text via the Aes256CbcEncrypter class.
string Encrypted = Aes256CbcEncrypter.Encrypt(Text, Key);
string Decrypted = Aes256CbcEncrypter.Decrypt(Encrypted, Key);
// Show the encrypted and decrypted data and the key used.
Console.WriteLine("Original: {0}", Text);
Console.WriteLine("Key: {0}", Key);
Console.WriteLine("Encrypted: {0}", Encrypted);
Console.WriteLine("Decrypted: {0}", Decrypted);
}
}
/**
* A class to encrypt and decrypt strings using the cipher AES-256-CBC.
*/
class Aes256CbcEncrypter
{
private static readonly Encoding encoding = Encoding.UTF8;
public static string Encrypt(string plainText, string key)
{
try
{
RijndaelManaged aes = new RijndaelManaged();
aes.KeySize = 256;
aes.BlockSize = 128;
aes.Padding = PaddingMode.PKCS7;
aes.Mode = CipherMode.CBC;
aes.Key = encoding.GetBytes(key);
aes.GenerateIV();
ICryptoTransform AESEncrypt = aes.CreateEncryptor(aes.Key, aes.IV);
byte[] buffer = encoding.GetBytes(plainText);
string encryptedText = Convert.ToBase64String(AESEncrypt.TransformFinalBlock(buffer, 0, buffer.Length));
String mac = "";
mac = BitConverter.ToString(HmacSHA256(Convert.ToBase64String(aes.IV) + encryptedText, key)).Replace("-", "").ToLower();
var keyValues = new Dictionary<string, object>
{
{ "iv", Convert.ToBase64String(aes.IV) },
{ "value", encryptedText },
{ "mac", mac },
};
JavaScriptSerializer serializer = new JavaScriptSerializer();
return Convert.ToBase64String(encoding.GetBytes(serializer.Serialize(keyValues)));
}
catch (Exception e)
{
throw new Exception("Error encrypting: " + e.Message);
}
}
public static string Decrypt(string plainText, string key)
{
try
{
RijndaelManaged aes = new RijndaelManaged();
aes.KeySize = 256;
aes.BlockSize = 128;
aes.Padding = PaddingMode.PKCS7;
aes.Mode = CipherMode.CBC;
aes.Key = encoding.GetBytes(key);
// Base 64 decode
byte[] base64Decoded = Convert.FromBase64String(plainText);
string base64DecodedStr = encoding.GetString(base64Decoded);
// JSON Decode base64Str
JavaScriptSerializer serializer = new JavaScriptSerializer();
var payload = serializer.Deserialize<Dictionary<string, string>>(base64DecodedStr);
aes.IV = Convert.FromBase64String(payload["iv"]);
ICryptoTransform AESDecrypt = aes.CreateDecryptor(aes.Key, aes.IV);
byte[] buffer = Convert.FromBase64String(payload["value"]);
return encoding.GetString(AESDecrypt.TransformFinalBlock(buffer, 0, buffer.Length));
}
catch (Exception e)
{
throw new Exception("Error decrypting: " + e.Message);
}
}
static byte[] HmacSHA256(String data, String key)
{
using (HMACSHA256 hmac = new HMACSHA256(encoding.GetBytes(key)))
{
return hmac.ComputeHash(encoding.GetBytes(data));
}
}
}
}
@doncadavona

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