Encryption in C# .NET

public class Encryption
{
    /// 

    /// Encrypts specified text using Rijndael symmetric key algorithm
    /// and returns a base64-encoded result.
    /// 
    /// 
    /// Plaintext value to be encrypted.
    /// 
    /// 
    /// Passphrase from which a pseudo-random password will be derived. The
    /// derived password will be used to generate the encryption key.
    /// Passphrase can be any string. In this example we assume that this
    /// passphrase is an ASCII string.        
    /// 
    /// 
    /// Salt value used along with passphrase to generate password. Salt can
    /// be any string. In this example we assume that salt is an ASCII string.
    /// 
    /// 
    /// Hash algorithm used to generate password. Allowed values are: "MD5" and
    /// "SHA1". SHA1 hashes are a bit slower, but more secure than MD5 hashes.
    /// 
    /// 
    /// Number of iterations used to generate password. One or two iterations
    /// should be enough.
    ///
    /// 
    /// Initialization vector (or IV). This value is required to encrypt the
    /// first block of plaintext data. For RijndaelManaged class IV must be
    /// exactly 16 ASCII characters long.
    ///
    /// 
    /// Size of encryption key in bits. Allowed values are: 128, 192, and 256.
    /// Longer keys are more secure than shorter keys.
    ///
    /// 
    /// Encrypted value formatted as a base64-encoded string.
    /// 
    public string Encrypt(string plainText, string passPhrase, string saltValue, string hashAlgorithm, int passwordIterations, string initVector, int keySize)
    {
        // Convert strings into byte arrays.
        // Let us assume that strings only contain ASCII codes.
        // If strings include Unicode characters, use Unicode, UTF7, or UTF8
        // encoding.
        byte[] initVectorBytes = Encoding.ASCII.GetBytes(initVector);
        byte[] saltValueBytes = Encoding.ASCII.GetBytes(saltValue);

        // Convert our plaintext into a byte array.
        // Let us assume that plaintext contains UTF8-encoded characters.
        byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);

        // First, we must create a password, from which the key will be derived.
        // This password will be generated from the specified passphrase and
        // salt value. The password will be created using the specified hash
        // algorithm. Password creation can be done in several iterations.
        PasswordDeriveBytes password = new PasswordDeriveBytes(passPhrase, saltValueBytes, hashAlgorithm, passwordIterations);

        // Use the password to generate pseudo-random bytes for the encryption
        // key. Specify the size of the key in bytes (instead of bits).
        byte[] keyBytes = password.GetBytes(keySize / 8);

        // Create uninitialized Rijndael encryption object.
        RijndaelManaged symmetricKey = new RijndaelManaged();

        // It is reasonable to set encryption mode to Cipher Block Chaining
        // (CBC). Use default options for other symmetric key parameters.
        symmetricKey.Mode = CipherMode.CBC;

        // Generate encryptor from the existing key bytes and initialization
        // vector. Key size will be defined based on the number of the key
        // bytes.
        ICryptoTransform encryptor = symmetricKey.CreateEncryptor(keyBytes, initVectorBytes);

        // Define memory stream which will be used to hold encrypted data.
        MemoryStream memoryStream = new MemoryStream();

        // Define cryptographic stream (always use Write mode for encryption).
        CryptoStream cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write);
        // Start encrypting.
        cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);

        // Finish encrypting.
        cryptoStream.FlushFinalBlock();

        // Convert our encrypted data from a memory stream into a byte array.
        byte[] cipherTextBytes = memoryStream.ToArray();

        // Close both streams.
        memoryStream.Close();
        cryptoStream.Close();

        // Convert encrypted data into a base64-encoded string.
        string cipherText = Convert.ToBase64String(cipherTextBytes);

        // Return encrypted string.
        return cipherText;
    }

    /// 

    /// Decrypts specified ciphertext using Rijndael symmetric key algorithm.
    /// 
    /// 
    /// Base64-formatted ciphertext value.
    ///
    /// 
    /// Passphrase from which a pseudo-random password will be derived. The
    /// derived password will be used to generate the encryption key.
    /// Passphrase can be any string. In this example we assume that this
    /// passphrase is an ASCII string.
    ///
    /// 
    /// Salt value used along with passphrase to generate password. Salt can
    /// be any string. In this example we assume that salt is an ASCII string.
    ///
    /// 
    /// Hash algorithm used to generate password. Allowed values are: "MD5" and
    /// "SHA1". SHA1 hashes are a bit slower, but more secure than MD5 hashes.
    ///
    /// 
    /// Number of iterations used to generate password. One or two iterations
    /// should be enough.
    ///
    /// 
    /// Initialization vector (or IV). This value is required to encrypt the
    /// first block of plaintext data. For RijndaelManaged class IV must be
    /// exactly 16 ASCII characters long.
    ///
    /// 
    /// Size of encryption key in bits. Allowed values are: 128, 192, and 256.
    /// Longer keys are more secure than shorter keys.
    ///
    /// 
    /// Decrypted string value.
    /// 
    /// 
    /// Most of the logic in this function is similar to the Encrypt
    /// logic. In order for decryption to work, all parameters of this function
    /// - except cipherText value - must match the corresponding parameters of
    /// the Encrypt function which was called to generate the
    /// ciphertext.
    /// 
    public string Decrypt(string cipherText, string passPhrase, string saltValue, string hashAlgorithm, int passwordIterations, string initVector, int keySize)
    {
        // Convert strings defining encryption key characteristics into byte
        // arrays. Let us assume that strings only contain ASCII codes.
        // If strings include Unicode characters, use Unicode, UTF7, or UTF8
        // encoding.
        byte[] initVectorBytes = Encoding.ASCII.GetBytes(initVector);
        byte[] saltValueBytes = Encoding.ASCII.GetBytes(saltValue);

        // Convert our ciphertext into a byte array.
        byte[] cipherTextBytes = Convert.FromBase64String(cipherText);

        // First, we must create a password, from which the key will be
        // derived. This password will be generated from the specified
        // passphrase and salt value. The password will be created using
        // the specified hash algorithm. Password creation can be done in
        // several iterations.
        PasswordDeriveBytes password = new PasswordDeriveBytes(passPhrase, saltValueBytes, hashAlgorithm, passwordIterations);

        // Use the password to generate pseudo-random bytes for the encryption
        // key. Specify the size of the key in bytes (instead of bits).
        byte[] keyBytes = password.GetBytes(keySize / 8);

        // Create uninitialized Rijndael encryption object.
        RijndaelManaged symmetricKey = new RijndaelManaged();

        // It is reasonable to set encryption mode to Cipher Block Chaining
        // (CBC). Use default options for other symmetric key parameters.
        symmetricKey.Mode = CipherMode.CBC;

        // Generate decryptor from the existing key bytes and initialization
        // vector. Key size will be defined based on the number of the key
        // bytes.
        ICryptoTransform decryptor = symmetricKey.CreateDecryptor(keyBytes, initVectorBytes);

        // Define memory stream which will be used to hold encrypted data.
        MemoryStream memoryStream = new MemoryStream(cipherTextBytes);

        // Define cryptographic stream (always use Read mode for encryption).
        CryptoStream cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read);

        // Since at this point we don't know what the size of decrypted data
        // will be, allocate the buffer long enough to hold ciphertext;
        // plaintext is never longer than ciphertext.
        byte[] plainTextBytes = new byte[cipherTextBytes.Length];

        // Start decrypting.
        int decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);

        // Close both streams.
        memoryStream.Close();
        cryptoStream.Close();

        // Convert decrypted data into a string.
        // Let us assume that the original plaintext string was UTF8-encoded.
        string plainText = Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);

        // Return decrypted string.
        return plainText;
    }
}