128-bit encryption

Question

How to write a Csharp programme which encrypt and decrypt the password using 128-bit encryption/decryption. Quick response will be appreciated. Thanks!! Munnu

munavvar hussain · Answer

I could find out the way to solve this. You can just create a class file and paste this onto it. Create a Login Page with the user id and password a submit button. On click of a submit button put the following code... //Declare this .. EnDecrypt128 oEnDe = new EnDecrypt128(); string EncryptPwdString; string DecryptPwdString; string key=&%&$ $@!!#()*^%^%$!@s *#; // This key can be anything. EncryptPwdString = oEnDe.EncryptString(txtPwd.Text key); DecryptPwdString = oEnDe.DecryptString(EncryptPwdString key); // EnDecrypt128.cs -- This is the class name. public string EncryptString(string InputText string Password) { // Password string variable is nothing but the key(your secret key) value which is sent from the front end. // InputText string variable is the actual password sent from the login page. // We are now going to create an instance of the // Rihndael class. RijndaelManaged RijndaelCipher = new RijndaelManaged(); // First we need to turn the input strings into a byte array. byte[] PlainText = System.Text.Encoding.Unicode.GetBytes(InputText); // We are using Salt to make it harder to guess our key // using a dictionary attack. byte[] Salt = Encoding.ASCII.GetBytes(Password.Length.ToString()); // The (Secret Key) will be generated from the specified // password and Salt. //PasswordDeriveBytes -- It Derives a key from a password PasswordDeriveBytes SecretKey = new PasswordDeriveBytes(Password Salt); // Create a encryptor from the existing SecretKey bytes. // We use 32 bytes for the secret key // (the default Rijndael key length is 256 bit = 32 bytes) and // then 16 bytes for the IV (initialization vector) // (the default Rijndael IV length is 128 bit = 16 bytes) ICryptoTransform Encryptor = RijndaelCipher.CreateEncryptor(SecretKey.GetBytes(16) SecretKey.GetBytes(16)); // Create a MemoryStream that is going to hold the encrypted bytes MemoryStream memoryStream = new MemoryStream(); // Create a CryptoStream through which we are going to be processing our data. // CryptoStreamMode.Write means that we are going to be writing data // to the stream and the output will be written in the MemoryStream // we have provided. (always use write mode for encryption) CryptoStream cryptoStream = new CryptoStream(memoryStream Encryptor CryptoStreamMode.Write); // Start the encryption process. cryptoStream.Write(PlainText 0 PlainText.Length); // Finish encrypting. cryptoStream.FlushFinalBlock(); // Convert our encrypted data from a memoryStream into a byte array. byte[] CipherBytes = memoryStream.ToArray(); // Close both streams. memoryStream.Close(); cryptoStream.Close(); // Convert encrypted data into a base64-encoded string. // A common mistake would be to use an Encoding class for that. // It does not work because not all byte values can be // represented by characters. We are going to be using Base64 encoding // That is designed exactly for what we are trying to do. string EncryptedData = Convert.ToBase64String(CipherBytes); // Return encrypted string. return EncryptedData; } -------------------------------------------------------------------- public string DecryptString(string InputText string Password) { RijndaelManaged RijndaelCipher = new RijndaelManaged(); byte[] EncryptedData = Convert.FromBase64String(InputText); byte[] Salt = Encoding.ASCII.GetBytes(Password.Length.ToString()); PasswordDeriveBytes SecretKey = new PasswordDeriveBytes(Password Salt); // Create a decryptor from the existing SecretKey bytes. ICryptoTransform Decryptor = RijndaelCipher.CreateDecryptor(SecretKey.GetBytes(16) SecretKey.GetBytes(16)); MemoryStream memoryStream = new MemoryStream(EncryptedData); // Create a CryptoStream. (always use Read mode for decryption). CryptoStream cryptoStream = new CryptoStream(memoryStream Decryptor CryptoStreamMode.Read); // Since at this point we don't know what the size of decrypted data // will be allocate the buffer long enough to hold EncryptedData; // DecryptedData is never longer than EncryptedData. byte[] PlainText = new byte[EncryptedData.Length]; // Start decrypting. int DecryptedCount = cryptoStream.Read(PlainText 0 PlainText.Length); memoryStream.Close(); cryptoStream.Close(); // Convert decrypted data into a string. string DecryptedData = Encoding.Unicode.GetString(PlainText 0 DecryptedCount); // Return decrypted string. return DecryptedData; } Note: Its taken from some of the article found in google and customised to my requirement. - Have a nice time...