RSA Encryption and Decryption using Private and Public Key, client and server side

RSA Encryption and Decryption using Private and Public Key, client and server side

Here i used two approach 

1. Server Side Encryption (using Public Key) and Server Side Decryption (using Private Key)

using System;
using System.Security.Cryptography;
using System.Text;

public partial class RSA_RSAEncDec : System.Web.UI.Page
{
    string publicKey = "";
    string privateKey = "";


    /*
     * Very Use full Site to develop this functionality
    //https://raskeyconverter.azurewebsites.net/XmlToPem?handler=ConvertPEM
    // For Encryption we user Private key PEM like below sample public key format i.e.  
    -----BEGIN PUBLIC KEY-----
    MIIBIjANBgkqhki....
-----END PUBLIC KEY-----

    For Decryption we required XMl file hence generate using the PEM and result like this..
    xpuS70fWBZv.....AQAB
+m+08g5NTiFXrh5f0...
ywUa2jNho8BFlQobo.....59OegfABWdD9tH4Dn7....B1t1AKlSBYQnQ....v4iZ7IpuX4yc....YC5TWCHX2duUR0a.....
    */
    protected void Page_Load(object sender, EventArgs e)
    {
		string PreFix = @"C:\Users\murdhusi\Downloads\Biometric (2)\Biometric\Murli\";
		publicKey = System.IO.File.ReadAllText(PreFix + @"RSApublicKeyM.txt");
        privateKey = System.IO.File.ReadAllText(PreFix + @"RSAprivateKeyM.txt");
    }

    protected void btnEncrypt_Click(object sender, EventArgs e)
    {
        txtencrypt.Text = GenerateKeyAndEncrypt();
    }

    protected void btnDecrypt_Click(object sender, EventArgs e)
    {
        txtdecrypt.Text = GetKeyandDecrypt(Convert.FromBase64String(txtencrypt.Text));
    }

    #region For Encryption
    private string GenerateKeyAndEncrypt()
    {
        // Generate RSA key pair
        using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
        {
            // Convert the data to bytes
            string data = txtplain.Text;// "Hello, RSA! MURLi";
            //lblMessage.Text += ("
 Orignal data: " + data);
            byte[] dataBytes = Encoding.UTF8.GetBytes(data);

            // Encrypt the data using the public key
            byte[] encryptedData = EncryptData(dataBytes, publicKey);

            string encData = Convert.ToBase64String(encryptedData);
            // Store or transmit the encrypted data
            //lblMessage.Text += ("
Encrypted data: " + encData);

            return encData;
        }
    }

    static byte[] EncryptData(byte[] dataBytes, string publicKey)
    {
        //if (true)
        {
            using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
            {
                // Import the recipient's public key
                rsa.FromXmlString(publicKey);

                // Encrypt the data using the public key
                byte[] encryptedData = rsa.Encrypt(dataBytes, true);

                return encryptedData;
            }
        }
    }
    #endregion

    #region For Decryption
    private string GetKeyandDecrypt(byte[] encData)
    {
        string originalData = "";
        string privateKeyXml = "";

        // Retrieve the encrypted data
        byte[] encryptedData = null; // Get the encrypted data

        privateKeyXml = privateKey;
        encryptedData = encData;

        // Create an instance of RSACryptoServiceProvider
        using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
        {
            // Import the private key
            rsa.FromXmlString(privateKeyXml);

            // Decrypt the data using the private key
            byte[] decryptedData = rsa.Decrypt(encryptedData, true);

            // Convert the decrypted data back to its original form
            originalData = Encoding.UTF8.GetString(decryptedData);

            // Display the decrypted data
            //lblMessage.Text += ("
Decrypted data: " + originalData);
        }
        return originalData;
    } 
    #endregion
}

2. Client Side Encryption (using Public Key) and Server Side Decryption (using Private Key)

<script src="https://cdn.jsdelivr.net/npm/jsencrypt@latest/bin/jsencrypt.min.js"></script>

    <script src="js/jsencrypt.min.js"></script>

<!--Your custom script that uses JSEncrypt-->

<script type="text/javascript">

    // Define the encryption function with a single parameter (the data to be encrypted).

    function encrypt(data) {

        //debugger;

        var encrypt = new JSEncrypt(); // Create a new instance of the JSEncrypt library.

        public_key = `-----BEGIN PUBLIC KEY-----

MIIBIjANBgkqhkiG9w.....

-----END PUBLIC KEY-----`;

        

        encrypt.setPublicKey(public_key); // Set the public key for the encryption library.

        var encrypted = encrypt.encrypt(data); // Use the encrypt method of the library to encrypt the data.

        //console.log("encrypted Text: ", encrypted);

        return encrypted; // Return the encrypted data.

    }

let encData = encrypt("Text for encryption");

</script>

Download Sample Code from here