To make things easier, I like to use a Symmetric utility with state, but this is just personal preference.
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
namespace BlogSandbox.encryption
{
public class SymmetricEncryption
{
public SymmetricAlgorithm Provider { get; set; }
public SymmetricEncryption
(SymmetricAlgorithm provider,
int keySize)
{
Provider = provider;
provider.KeySize = keySize;
}
public SymmetricEncryption(
SymmetricAlgorithm provider,
byte[] key,
byte[] iv)
{
Provider = provider;
provider.Key = key;
provider.IV = iv;
}
public byte[] GetKey()
{
return Provider.Key;
}
public byte[] GetIv()
{
return Provider.IV;
}
public byte[] Encrypt(byte[] message)
{
return TransformMessage(message,
Provider.CreateEncryptor());
}
public string Encrypt(string message)
{
byte[] encrypted = TransformMessage(
Encoding.UTF8.GetBytes(message),
Provider.CreateEncryptor());
return Convert.ToBase64String(encrypted);
}
public byte[] Decrypt(byte[] message)
{
return TransformMessage(message,
Provider.CreateDecryptor());
}
public string Decrypt(string message)
{
byte[] decrypted = TransformMessage(
Convert.FromBase64String(message),
Provider.CreateDecryptor());
return Encoding.UTF8.GetString(decrypted);
}
private byte[] TransformMessage(byte[] message,
ICryptoTransform cryptoTransform)
{
MemoryStream memoryStream = new MemoryStream();
CryptoStream cryptoStream = new CryptoStream(
memoryStream,
cryptoTransform,
CryptoStreamMode.Write);
// write message to be encrypted and flush
cryptoStream.Write(message, 0, message.Length);
cryptoStream.FlushFinalBlock();
// read encrypted message into a byte[]
memoryStream.Position = 0;
byte[] result = memoryStream.ToArray();
// close up the streams
memoryStream.Close();
cryptoStream.Close();
return result;
}
}
}
When using this utility, you have the option of passing in your own key/IV or having it randomly generated by the provider. In the test code, I will simply have it generated by the provider and is the use case for all of these posts. Here is some test code:
namespace BlogSandbox
{
class Program
{
static void Main(string[] args)
{
string testText = "encrypt and decrypt me";
SymmetricEncryption enc = new SymmetricEncryption(
CryptoConfig.CreateFromName("AesManaged")
as SymmetricAlgorithm,
256);
string encText = enc.Encrypt(testText);
Console.WriteLine("Encrypted: " + encText);
string decText = enc.Decrypt(encText);
Console.WriteLine("Decrypted: " + decText);
Thread.Sleep(20000);
}
}
}
That's it for symmetric encryption/decryption. In the next post I will cover Asymmetric encryption/decryption...
