Encrypt and Decrypt a String in C# using Cryptography

I am going to explain how to encrypt and decrypt a string in C# using Cryptography and by generating an MD5 hash from the password.

First of all we need to add System.Security.Cryptography; namespace in our code, I am going to create a class with two Methods

1) Encrypter
2) Decrypter

Encrypter used to encrypt a string and Decrypter used to descrypt the string encrypted by Encrypter.

Here is this beautiful class. Its a competetely implemented Class, what all you need to do is just Copy and Paste.

public class EncryptDecrypt
{
public EncryptDecrypt()
{
//
// TODO: Add constructor logic here
//
}

public string Encrypter(string strStringToEncrypt)
{
string strOriginal, strEncryptedString, password;
TripleDESCryptoServiceProvider des;
MD5CryptoServiceProvider hashmd5;
byte[] pwdhash, buff;

//create a secret password. the password is used to encrypt and decrypt
//strings. Without the password, the encrypted string cannot be
//decrypted and is just garbage. You must use the same password to
//decrypt an encrypted string as the string was originally encrypted with.

password = "manojjoshi";

//create a string to encrypt
//original = "String to encrypt";

strOriginal = strStringToEncrypt;

//generate an MD5 hash from the password.a hash is a one way
//encryption meaning once you generate the hash, you cant derive the
//password back from it.

hashmd5 = new MD5CryptoServiceProvider();
pwdhash = hashmd5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(password));
hashmd5 = null;

//implement DES3 encryption
des = new TripleDESCryptoServiceProvider();

//the key is the secret password hash.
des.Key = pwdhash;

//the mode is the block cipher mode which is basically the details of how
//the encryption will work. There are several kinds of ciphers available in
//DES3 and they all have benefits and drawbacks. Here the Electronic
//Codebook cipher is used which means that it encrypt each
//block individually and a given bit of text is always encrypted exactly the
// same when the same password is used.

des.Mode = CipherMode.ECB; //CBC, CFB


//----- encrypt an un-encrypted string ------------
//the original string, which needs encrypted, must be in byte array
//form to work with the des3 class. everything will because most encryption
//works at the byte level so you'll find that the class takes in byte
//arrays and returns byte arrays and you'll be converting
//those arrays to strings.

buff = ASCIIEncoding.ASCII.GetBytes(strOriginal);

//encrypt the byte buffer representation of the original string and base64
//encode the encrypted string. The reason the encrypted bytes are being
//base64 encoded as string is the encryption will have created some weird
//characters in there. Base64 encoding provides a platform independent view
//of the encrypted string and can be sent as a plain text string to wherever.

strEncryptedString = Convert.ToBase64String(
des.CreateEncryptor().TransformFinalBlock(buff, 0, buff.Length)
);

return strEncryptedString;
}

public string Decrypter(string StrEncryptedString)
{
string decrypted, password;
TripleDESCryptoServiceProvider des;
MD5CryptoServiceProvider hashmd5;
byte[] pwdhash, buff;

//create a secret password. the password is used to encrypt
//and decrypt strings. Without the password, the encrypted
//string cannot be decrypted and is just garbage. You must
//use the same password to decrypt an encrypted string as the
//string was originally encrypted with.
password = "manojjoshi

//generate an MD5 hash from the password.
//a hash is a one way encryption meaning once you generate
//the hash, you cant derive the password back from it.
hashmd5 = new MD5CryptoServiceProvider();
pwdhash = hashmd5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(password));
hashmd5 = null;

//implement DES3 encryption
des = new TripleDESCryptoServiceProvider();

//the key is the secret password hash.
des.Key = pwdhash;

//the mode is the block cipher mode which is basically the
//details of how the encryption will work. There are several
//kinds of ciphers available in DES3 and they all have benefits
//and drawbacks. Here the Electronic Codebook cipher is used
//which means that a given bit of text is always encrypted
//exactly the same when the same password is used.
des.Mode = CipherMode.ECB; //CBC, CFB


//----- decrypt an encrypted string ------------
//whenever you decrypt a string, you must do everything you
//did to encrypt the string, but in reverse order. To encrypt,
//first a normal string was des3 encrypted into a byte array
//and then base64 encoded for reliable transmission. So, to
//decrypt this string, first the base64 encoded string must be
//decoded so that just the encrypted byte array remains.
buff = Convert.FromBase64String(StrEncryptedString);

//decrypt DES 3 encrypted byte buffer and return ASCII string
decrypted = ASCIIEncoding.ASCII.GetString(
des.CreateDecryptor().TransformFinalBlock(buff, 0, buff.Length)
);

return decrypted;
}


}

And we are done with this. Now play with encryption and decryption Cheers..