In previous blog Ã¢â‚¬â€œ [ Cryptography : Symmetric Encryption by Symmetric Algorithm Classes Ã¢â‚¬â€œ Part 1
] we have learned about basic introduction of Cryptography , Symmetric
Encryption , Symmetric Encryption Algorithm classes and codes for
implementing DES class.

so, now In addition to previous blog here we will learn about TripleDES class, RC2 class and Rijndael class.

## TripleDES class

The TripleDES class is an abstract class that extends the
SymmetricAlgorithm class and provides support for the Triple Data
Encryption Standard(Triple DES or TDES or TDEA) algorithm. TripleDES is a
method kind of using DES(Data Encryption Standard) to provide
additional security. TripleDES can be done by using two or with three
keys.

TripleDES as its name implies increase encryption strength by applying
the DES encryption algorithm to data three times before rendering to a
result. Since the algorithm performs an encrypt-decrypt-encrypt
sequence, this is sometimes called the EDE(Encryption Decryption
Encryption) mode. TripleDES algorithm supports an encryption key up to
168 bits (3*156) in size to 192 bits (Triple DES utilizes three 64-bit
keys, 64*3 bits) in increments of 64 bits. Triple DES gives a relatively
simple and awesome method of increasing the key size of DES(Data
Encryption Standard) to protect against attacks.

The following code sample guide you how to use and implement the TripleDESCryptoServiceProvider class.

Note SourceCode was almost same as we have read in previous article.
Just Implantation are different so keep focus on Implementation code.

To perform Encryption and Decryption. you must add

`1` | `using` `System.Security.Cryptography; ` |

Now take a look at encryption function

`01` | `public` `static` `byte` `[] Encrypt(` `string` `strText, SymmetricAlgorithm key)` |

`04` | `MemoryStream ms = ` `new` `MemoryStream();` |

`07` | `CryptoStream crypstream = ` `new` `CryptoStream(ms, key.CreateEncryptor(), CryptoStreamMode.Write);` |

`09` | `StreamWriter sw = ` `new` `StreamWriter(crypstream);` |

`16` | `byte` `[] buffer = ms.ToArray();` |

In above code, CreateEncryptor() function is used to encryptor object with the current Key property and initialization vector.

Now in same way we need to create function for Decrypt the PlainText(Encrypted Text)

have a look at given function which is responsible to decrypt encrypted text.

`01` | `public` `static` `string` `Decrypt(` `byte` `[] encryptText, SymmetricAlgorithm key)` |

`05` | ` ` `MemoryStream ms = ` `new` `MemoryStream(encryptText);` |

`07` | ` ` `CryptoStream crypstream = ` `new` `CryptoStream(ms, key.CreateDecryptor(), CryptoStreamMode.Read);` |

`09` | ` ` `StreamReader sr = ` `new` `StreamReader(crypstream);` |

`11` | ` ` `string` `val = sr.ReadLine();` |

In above code, decryption is handled in same way by using CreateDecryptor() function instead of CreateEncryptor()

Now we have created function, so we can use both function to appropriate manner to accomplishment of Encryption Decryption task.

**Note : we need to access TripleDESCryptoServiceProvider class here.**

`1` | `TripleDESCryptoServiceProvider key = ` `new` `TripleDESCryptoServiceProvider(); ` |

**How to use Encrypt Function**

`2` | `TripleDESCryptoServiceProvider key = ` `new` `TripleDESCryptoServiceProvider();` |

`4` | ` ` `byte` `[] buffer = Encrypt(` `"ABC"` `, key); ` |

**How to use Decrypt Function**

`2` | `TripleDESCryptoServiceProvider key = ` `new` `TripleDESCryptoServiceProvider();` |

`4` | `byte` `[] buffer = Encrypt(` `"ABC"` `, key);` |

`5` | `string` `strText = Decrypt(buffer, key); ` |

## RC2 class

The RC2 classis an abstract class that extends the Symmetric Algorithm class and provides support for the RC2 algorithm.

Ron Rivest He is the one who discovered RC2, RC4, RC5, and RC6. Hence RC stands for RonÃ¢â‚¬â„¢s Codes. however Lotus Software Company is the backend in creating the whole script of RC2 algorithm.

The RC2CryptoServiceProvider object is a block cipher that encrypts
and decrypts data in blocks of 8 bytes. This class pads the final block
of data if it is less than 8 bytes. As a result of this padding, the
length of encrypted data could be greater than the original plaintext.

The RC2 class provides the EffectiveKeySize property, which is used to
get or set the effective key size of the RC2 secret encryption key. An
exception is occured whenever size is detected. The RC2CryptoServiceProvider class is the concrete RC2 algorithm class and it extends the RC2 class. The RC2CryptoServiceProvider
class provides the UseSalt Property. The UseSalt proeperty is set to
false by deafult. However in any condition if this(usesalt) property is
set to True, the encrypted value includes an 11-byte long 0 value salt.

Note : we need to access RC2CryptoServiceProvider class here.

`1` | `RC2CryptoServiceProvider key = ` `new` `RC2CryptoServiceProvider();` |

The same Function of Encryption and Decryption which we used in
previous Symmetric Encryption program. Just point to be noted to change
the Symmetric class here which is RC2CryptoServiceProvider for RC2
encryption.

**How to use Encrypt Function**

`2` | `RC2CryptoServiceProvider key = ` `new` `RC2CryptoServiceProvider();` |

`4` | ` ` `byte` `[] buffer = Encrypt(` `"ABC"` `, key); ` |

**How to use Decrypt Function**

`2` | `RC2CryptoServiceProvider key = ` `new` `RC2CryptoServiceProvider();` |

`4` | `byte` `[] buffer = Encrypt(` `"ABC"` `, key);` |

`5` | `string` `strText = Decrypt(buffer, key); ` |

## Rijndael Class

The Rijndael class is an abstract class that extends the
SymmetricAlgorithm class and provides support for the Rijndael
algorithm. The algorithm of Rijndael encryption has been designed to
replace the aging DES(Data Encryption Standard) algorithm. Like DES, it
is a block cipher. It uses 128-bit, 192-bit or 256-bit keys. This
implementation encrypts 128-bit blocks. (DES used 56-bit keys and 64-bit
blocks.)

As we have read It is considered to be the replacement for the DES algorithm and was adopted as a Federal Information Processing Standard(FIPS) standard in 2001. The RijndaelManaged
class is a concrete class and it extends the Rijndael class. The
Rijndael class is extended by CLR managed class, whereas the Symmetric
encryption classes are extened by CSPs. The RijndaelManagedTransform
class is initialized by the CreateEncryptor and CreateDecryptor methods
of the RijndaelManaged class and is used in conjuction with the
RijndaelMaaged class to encrypt data.

In .NetFramework Rijndael algorithm supports a fixed encryption key size of 128 bits, 192 bits, 192 bits or 256 bits as **9
rounds if the key/block size is 128 bits ,11 rounds if the key/block
size is 192 bits and 13 rounds if the key/block size is 256 bits**

The Rijndael class is the predecessor of the Aes algorithm. You should use the Aes algorithm instead of Rijndael.

Note : we need to access RijndaelManaged class here.

`1` | `RijndaelManaged key = ` `new` `RijndaelManaged();` |

The same Function of Encryption and Decryption which we used in
previous Symmetric Encryption program. Just point to be noted to change
the Symmetric class here which is RijndaelManaged for Rijndael encryption.

**How to use Encrypt Function**

`2` | `RijndaelManaged key = ` `new` `RijndaelManaged();` |

`4` | ` ` `byte` `[] buffer = Encrypt(` `"ABC"` `, key); ` |

**How to use Decrypt Function**

`2` | `RijndaelManaged key = ` `new` `RijndaelManaged();` |

`4` | `byte` `[] buffer = Encrypt(` `"ABC"` `, key);` |

`5` | `string` `strText = Decrypt(buffer, key); ` |

**Look at given below for output by using different Symmetric Algorithm applied on same plain text (eg : ABC)**