Encryption in C# Continue

From our previous article Encryption in C#, encryption is the process of translating plain text data (plaintext) into something that appears to be random and meaningless (ciphertext). It is used to transform a data into some un-readable form so that authenticated person only can read/access the data. It requires some secret information to transform the plain text to cipher text; it is usually referred as key.

Decryption is the process of converting ciphertext back to plaintext. To encrypt more than a small amount of data, symmetric encryption is used.

There are many modern cryptographic methods used for encryption and decryption and it is classified in to two classes of key based algorithms.

1.      Symmetric Algorithm

o    Same key is used for both Encryption and Decryption. The key will be kept as secret.

o    Symmetric Ciphers is divided into Stream and Block Ciphers.

§  Stream Ciphers – It encrypts a single bit of plain text at a time.

§  Block Ciphers – It takes number of bits and encrypts them as a single unit.

2.     Asymmetric Algorithm

o    Different key is used for Encryption and Decryption. It is also called as public Key algorithm.

o    Encryption key is public and the Decryption key will be kept as secret.

o    By using this asymmetric algorithm, anyone can encrypt the message by using encryption key but the message can be decrypted only by using decryption key.

3.     Hybrid Encryption – Symmetric and Asymmetric algorithm are used together and it is called as Hybrid Encryption.

Symmetric Encryption Algorithm are as below

• Data Encryption Standard (DES)
• Blow Fish
• Triple DES (3DES)
• Advanced Encryption Standard (AES)

The code snippets below demonstrate the encryption and decryption using C# programming Language

Encryption

public static string EncryptText(string plainText)

        {

            //Convert the plain text to bytes array

            var plaintextToArray = UTF8Encoding.UTF8.GetBytes(plainText);

            //Instantiate the MD5 cryptor Service provider

            MD5CryptoServiceProvider serviceProvider = new MD5CryptoServiceProvider();

 

            var securityKeyArray = serviceProvider.ComputeHash(UTF8Encoding.UTF8.GetBytes(securityKey));

            //

            serviceProvider.Clear();

            // Data encryption Standard Service Provider

            var desServiceProvider = new TripleDESCryptoServiceProvider

            {

                Key = securityKeyArray,

                Mode = CipherMode.ECB,

                Padding = PaddingMode.PKCS7

            };

          // Create Encryption

            var cryptoTransform = desServiceProvider.CreateEncryptor();

 

            byte[] encrytedArray = cryptoTransform.TransformFinalBlock(plaintextToArray, 0, plaintextToArray.Length);

 

            desServiceProvider.Clear();

 

            return Convert.ToBase64String(encrytedArray, 0, encrytedArray.Length);

        }

 

Decryption

public static string DecryptText(string encryptedText)

        {

            var encryptedTextArray = Convert.FromBase64String(encryptedText);

 

            var cryptoServiceProvider = new MD5CryptoServiceProvider();

 

            var secuKey = cryptoServiceProvider.ComputeHash(UTF8Encoding.UTF8.GetBytes(securityKey));

            //

            cryptoServiceProvider.Clear();

 

            var desTripleCryptoService = new TripleDESCryptoServiceProvider

            {

                Key = secuKey,

                Mode = CipherMode.ECB,

                Padding = PaddingMode.PKCS7

            };

 

            var cryptoTransform = desTripleCryptoService.CreateDecryptor();

 

            var decryptedArray = cryptoTransform.TransformFinalBlock(encryptedTextArray, 0, encryptedTextArray.Length);

            //

            desTripleCryptoService.Clear();

            //

            return UTF8Encoding.UTF8.GetString(decryptedArray);

        }

Thank you