private void OnComputeHash(object sender, System.EventArgs e)
{
    // Convert A to byte array
    Byte[] data1ToHash = ConvertStringToByteArray(adata.Text);
    // Convert B to byte array
    Byte[] data2ToHash = ConvertStringToByteArray(bdata.Text);

    // Create hash value from String 1 using MD5
    // instance returned by Crypto Config system
    byte[] hashvaluea = ((HashAlgorithm) CryptoConfig.CreateFromName("MD5")).ComputeHash
(data1ToHash);

    ahash.Text = BitConverter.ToString(hashvaluea);

    // Create hash value of String 2 using directly
    // created instance of the MD5 class
    byte[] hashvalueb = (new MD5CryptoServiceProvider()).ComputeHash(data2ToHash);
    bhash.Text = BitConverter.ToString(hashvalueb);

    // Memberwise compare of hash value bytes
    bool same = true;
    if(hashvaluea.Length == hashvalueb.Length)
    {
        int i = 0;
        do
        {
            if(hashvaluea[i] != hashvalueb[i])
            {
                same = false;
                break;
            }
            i++;
        }
        while(i < hashvaluea.Length);
    }
    else
        same = false;
    if(same)
        comparison.Text = "Same";
    else
        comparison.Text = "Different";
}

// Request Security Package

. . .
// Send Initial Authentication Userid

. . .

// Parse MD5 Hash Check Response
// Format: USR 5 MD5 S 989048851.1851137130

. . .
// str3 = MD5 Hash Check
str3 = str3.Trim();
str2 = str3 + _password;

// Obtain MD5 Hash

MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
byte[] md5hash = md5.ComputeHash(Encoding.UTF8.GetBytes(str2));
str1 = GetByteString(md5hash);

tid = Convert.ToString(MessengerForm.GetNextTrialID());
str2 = "USR " + tid + " MD5 S " + str1;
SendNSData(str2);
str1 = ReceiveNSData();

private void OnEncrypt(object sender, System.EventArgs e)
{
    // Create the file streams to handle the input and output files.
    FileStream fin = new FileStream(filePath.Text, FileMode.Open, FileAccess.Read);
    FileStream fout = new FileStream(encryptedPath.Text, FileMode.OpenOrCreate, FileAccess
.Write);
    fout.SetLength(0);

    // Create variables to help with read and write.
    // This is intermediate storage for the encryption.
    byte[] bin = new byte[fileChunkSize];
    // This is the total number of bytes written.
    long rdlen = 0;
    // This is the total length of the input file.
    long totlen = fin.Length;
    // This is the number of bytes to be written at a time.
    int len;

    Debug.WriteLine("Encrypting...");
    DateTime start = DateTime.Now;

    // Creates the default implementation
    //DES instance with random key
    DESCryptoServiceProvider des = new DESCryptoServiceProvider();
    fileKey = des.Key;
    fileIV = des.IV;

    //Create DES Encryptor from this instance
    ICryptoTransform desencrypt = des.CreateEncryptor();

    //Create Crypto Stream that transforms file stream using des encryption
    CryptoStream encStream = new CryptoStream(fout,desencrypt,CryptoStreamMode.Write);

    //Read from the input file; then encrypt and write to the output file.
    while(rdlen < totlen)
    {
        len = fin.Read(bin, 0, fileChunkSize);
        encStream.Write(bin, 0, len);
        rdlen = rdlen + len;
    }
    fileSize.Text = Convert.ToString(rdlen);
    encStream.Close();
    fout.Close();
    fin.Close();
    DateTime stop = DateTime.Now;
    TimeSpan elapsed = stop - start;
    encryptTime.Text = string.Format("{0:F} ", (double)elapsed.TotalMilliseconds / 1000.0);
    decryptButton.Enabled = true;
}

private void OnDecrypt(object sender, System.EventArgs e)
{
    // Create the file streams to handle the input and output files.
    FileStream fin = new FileStream(encryptedPath.Text, FileMode.Open, FileAccess.Read);
    FileStream fout = new FileStream(filePath.Text + ".decrypted", FileMode.OpenOrCreate,
 FileAccess.Write);

    // Create variables to help with read and write.
    // This is intermediate storage for the encryption.
    byte[] bin = new byte[fileChunkSize];
    // This is the total number of bytes written.
    long rdlen = 0;
    // This is the total length of the input file.
    long totlen = fin.Length;
    // This is the number of bytes to be written at a time.
    int len;

    DateTime start = DateTime.Now;
    Debug.WriteLine("Decrypting...");

    // Creates the default implementation, which is RijndaelManaged.
    //DES instance with random key
    DESCryptoServiceProvider des = new DESCryptoServiceProvider();
    //create DES Encryptor from this instance
    ICryptoTransform desdecrypt = des.CreateDecryptor(fileKey, fileIV);

    //Create Crypto Stream that transforms file stream using des encryption
    CryptoStream decStream = new CryptoStream(fout, desdecrypt, CryptoStreamMode.Write);

    //Read from the input file; then encrypt and write to the output file.
    while(rdlen < totlen)
    {
        len = fin.Read(bin, 0, fileChunkSize);
        decStream.Write(bin, 0, len);
        rdlen = rdlen + len;
    }
    encryptedSize.Text = Convert.ToString(rdlen);
    decStream.Close();
    fout.Close();
    fin.Close();
    DateTime stop = DateTime.Now;
    TimeSpan elapsed = stop - start;
    decryptTime.Text = string.Format("{0:F} ", (double)elapsed.TotalMilliseconds / 1000.0);
}