String Encryption and Decryption in C# using Cryptography.Rijndael algorithm.

Here is the sample coding for string Encryption and Decryption using Rijndael algorithm.


using System.Security.Cryptography;
using System.IO;

public static string Encrypt(string clearText, string Password)
{
byte[] clearBytes = System.Text.Encoding.Unicode.GetBytes(clearText);
PasswordDeriveBytes pdb = new PasswordDeriveBytes(Password,
new byte[] {0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d,
0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76});

// PasswordDeriveBytes is for getting Key and IV.
// Using PasswordDeriveBytes object we are first getting 32 bytes for the Key (the default
//Rijndael key length is 256bit = 32bytes) and then 16 bytes for the IV.
// IV should always be the block size, which is by default 16 bytes (128 bit) for Rijndael.

byte[] encryptedData = Encrypt(clearBytes, pdb.GetBytes(32), pdb.GetBytes(16));
return Convert.ToBase64String(encryptedData);
}


// Encrypt a byte array into a byte array using a key and an IV

public static byte[] Encrypt(byte[] clearData, byte[] Key, byte[] IV)
{
MemoryStream ms = new MemoryStream();
Rijndael alg = Rijndael.Create();

// Algorithm. Rijndael is available on all platforms.

alg.Key = Key;
alg.IV = IV;
CryptoStream cs = new CryptoStream(ms, alg.CreateEncryptor(), CryptoStreamMode.Write);

//CryptoStream is for pumping our data.

cs.Write(clearData, 0, clearData.Length);
cs.Close();
byte[] encryptedData = ms.ToArray();
return encryptedData;
}


public static byte[] Decrypt(byte[] cipherData, byte[] Key, byte[] IV)
{
MemoryStream ms = new MemoryStream();
Rijndael alg = Rijndael.Create();
alg.Key = Key;
alg.IV = IV;
CryptoStream cs = new CryptoStream(ms,alg.CreateDecryptor(), CryptoStreamMode.Write);
cs.Write(cipherData, 0, cipherData.Length);
cs.Close();
byte[] decryptedData = ms.ToArray();
return decryptedData;
}


// Decrypt a string into a string using a password
// Uses Decrypt(byte[], byte[], byte[])


public static string Decrypt(string cipherText, string Password)
{
byte[] cipherBytes = Convert.FromBase64String(cipherText);
PasswordDeriveBytes pdb = new PasswordDeriveBytes(Password,
new byte[] {0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65,
0x64, 0x76, 0x65, 0x64, 0x65, 0x76});
byte[] decryptedData = Decrypt(cipherBytes, pdb.GetBytes(32), pdb.GetBytes(16));
return System.Text.Encoding.Unicode.GetString(decryptedData);
}