Simple String Encryption and Decryption with Source Code

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Introduction

This article helps the C# beginners to do simple encryption and decryption of strings. It will be useful for simple password encryption or any such string encryption.

Encryption using the default key:

Encryption using the user's custom key:

Decryption using the user's custom key:

Using the Code

The demo application uses a class SSTCryptographer which contains two static overloaded methods and a static property. 

How To Use the Given Code

On Button clicks:

private void btnEncrypt_Click(object sender, EventArgs e)
{ 
txtOutputText.Text = SSTCryptographer.Encrypt(txtInputText.Text,SetKey());
}
private void btnDecrypt_Click(object sender, EventArgs e)
{
txtOutputText.Text = SSTCryptographer.Decrypt(txtInputText.Text,SetKey());
}

/// <summary>
/// Encrypt the given string using the default key.
/// </summary>
/// <param name="strToEncrypt">The string to be encrypted.</param>
/// <returns>The encrypted string.</returns>
public static string Encrypt(string strToEncrypt)
{
    try
    {
        return Encrypt(strToEncrypt, _key);
    }

    catch (Exception ex)
    {
        return "Wrong Input. " + ex.Message;
    }
} 

/// <summary>
/// Decrypt the given string using the default key.
/// </summary>
/// <param name="strEncrypted">The string to be decrypted.</param>
/// <returns>The decrypted string.</returns>
public static string Decrypt(string strEncrypted)
{
    try
    {
        return Decrypt(strEncrypted, _key);
    }
    catch (Exception ex)
    {
        return "Wrong Input. " + ex.Message;
    }
}

/// <summary>
/// Encrypt the given string using the specified key.
/// </summary>
/// <param name="strToEncrypt">The string to be encrypted.</param>
/// <param name="strKey">The encryption key.</param>
/// <returns>The encrypted string.</returns>
public static string Encrypt(string strToEncrypt, string strKey)
{
    try
    {
        TripleDESCryptoServiceProvider objDESCrypto = 
			new TripleDESCryptoServiceProvider();
        MD5CryptoServiceProvider objHashMD5 = new MD5CryptoServiceProvider();
        byte[] byteHash, byteBuff;
        string strTempKey = strKey;
        byteHash = objHashMD5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(strTempKey));
        objHashMD5 = null;
        objDESCrypto.Key = byteHash;
        objDESCrypto.Mode = CipherMode.ECB; //CBC, CFB
        byteBuff = ASCIIEncoding.ASCII.GetBytes(strToEncrypt);
        return Convert.ToBase64String(objDESCrypto.CreateEncryptor().
			TransformFinalBlock(byteBuff, 0, byteBuff.Length));
    }
    catch (Exception ex)
    {
        return "Wrong Input. " + ex.Message;
    }
}

/// <summary>
/// Decrypt the given string using the specified key.
/// </summary>
/// <param name="strEncrypted">The string to be decrypted.</param>
/// <param name="strKey">The decryption key.</param>
/// <returns>The decrypted string.</returns>
public static string Decrypt(string strEncrypted, string strKey)
{
    try
    {
        TripleDESCryptoServiceProvider objDESCrypto = 
			new TripleDESCryptoServiceProvider();
        MD5CryptoServiceProvider objHashMD5 = new MD5CryptoServiceProvider();
        byte[] byteHash, byteBuff;
        string strTempKey = strKey;
        byteHash = objHashMD5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(strTempKey));
        objHashMD5 = null;
        objDESCrypto.Key = byteHash;
        objDESCrypto.Mode = CipherMode.ECB; //CBC, CFB
        byteBuff = Convert.FromBase64String(strEncrypted);
        string strDecrypted = ASCIIEncoding.ASCII.GetString
		(objDESCrypto.CreateDecryptor().TransformFinalBlock
		(byteBuff, 0, byteBuff.Length));
        objDESCrypto = null;
        return strDecrypted;
    }
    catch (Exception ex)
    {
        return "Wrong Input. " + ex.Message;
    }
}