Introduction To AES And DES Encryption Algorithms In .NET

public string DecryptData(string strData, string strKey)
{
    byte[] key = { }; // Key
    byte[] IV = { 10, 20, 30, 40, 50, 60, 70, 80 };
    byte[] inputByteArray = new byte[strData.Length];
    try
    {
        key = Encoding.UTF8.GetBytes(strKey);
        DESCryptoServiceProvider ObjDES = new DESCryptoServiceProvider();
        inputByteArray = Convert.FromBase64String(strData);
        MemoryStream Objmst = new MemoryStream();
        CryptoStream Objcs = new CryptoStream(Objmst, ObjDES.CreateDecryptor(key, IV), CryptoStreamMode.Write);
        Objcs.Write(inputByteArray, 0, inputByteArray.Length);
        Objcs.FlushFinalBlock();
        Encoding encoding = Encoding.UTF8;
        return encoding.GetString(Objmst.ToArray());
    }
    catch (System.Exception ex)
    {
        throw ex;
    }
}

3DES - Called Triple DES

As we have seen, there are some security-related issues in the DES algorithm, so we can say that 3DES is an updated version of DES. In the 3DES, they also increase the key size, which was very short in DES.

AES Advanced Encryption Standard

The Advanced Encryption Standard or AES is also called Rijndael cipher. AES supports 128, 192, and 256-bit encryption, which can be determined by the key size, 128-bit encryption key size is 16 bytes, the 192-bit encryption key is 24 bytes and 256-bit encryption key size is 32 bytes. AES Encryption offers good performance and a good level of security. AES Encryption is a symmetric cipher and uses the same key for encryption and decryption.

Encryption code

Encryption code Check the comments in the code for more details.

string EncryptData(string textData, string Encryptionkey)
{
    RijndaelManaged objrij = new RijndaelManaged();
    // Set the mode for operation of the algorithm
    objrij.Mode = CipherMode.CBC;
    // Set the padding mode used in the algorithm
    objrij.Padding = PaddingMode.PKCS7;
    // Set the size, in bits, for the secret key
    objrij.KeySize = 0x80;
    // Set the block size in bits for the cryptographic operation
    objrij.BlockSize = 0x80;
    // Set the symmetric key that is used for encryption & decryption
    byte[] passBytes = Encoding.UTF8.GetBytes(Encryptionkey);
    // Set the initialization vector (IV) for the symmetric algorithm
    byte[] EncryptionkeyBytes = new byte[] { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
    int len = passBytes.Length;
    if (len > EncryptionkeyBytes.Length)
    {
        len = EncryptionkeyBytes.Length;
    }
    Array.Copy(passBytes, EncryptionkeyBytes, len);
    objrij.Key = EncryptionkeyBytes;
    objrij.IV = EncryptionkeyBytes;
    // Creates a symmetric AES object with the current key and initialization vector IV
    ICryptoTransform objtransform = objrij.CreateEncryptor();
    byte[] textDataByte = Encoding.UTF8.GetBytes(textData);
    // Final transform the test string
    return Convert.ToBase64String(objtransform.TransformFinalBlock(textDataByte, 0, textDataByte.Length));
}

Decryption code

string DecryptData(string EncryptedText, string Encryptionkey)
{
    RijndaelManaged objrij = new RijndaelManaged();
    objrij.Mode = CipherMode.CBC;
    objrij.Padding = PaddingMode.PKCS7;
    objrij.KeySize = 0x80;
    objrij.BlockSize = 0x80;
    byte[] encryptedTextByte = Convert.FromBase64String(EncryptedText);
    byte[] passBytes = Encoding.UTF8.GetBytes(Encryptionkey);
    byte[] EncryptionkeyBytes = new byte[0x10];
    int len = passBytes.Length;
    if (len > EncryptionkeyBytes.Length)
    {
        len = EncryptionkeyBytes.Length;
    }
    Array.Copy(passBytes, EncryptionkeyBytes, len);
    objrij.Key = EncryptionkeyBytes;
    objrij.IV = EncryptionkeyBytes;
    byte[] TextByte = objrij.CreateDecryptor().TransformFinalBlock(encryptedTextByte, 0, encryptedTextByte.Length);
    return Encoding.UTF8.GetString(TextByte); // it will return readable string
}

In the next article, I will explain Asymmetric Encryption RSA, DSA.