rsa encryption in nodejs code example

Example 1: rsa encryption js

//src https://www.sohamkamani.com/nodejs/rsa-encryption/
//e.g. https://gist.github.com/sohamkamani/b14a9053551dbe59c39f83e25c829ea7
////////////////////////////////////////////////////////////////
npm install crypto
///////////////////////////////////////////////////////////////
const crypto = require("crypto")


// The `generateKeyPairSync` method accepts two arguments:
// 1. The type ok keys we want, which in this case is "rsa"
// 2. An object with the properties of the key
const { publicKey, privateKey } = crypto.generateKeyPairSync("rsa", {
	// The standard secure default length for RSA keys is 2048 bits
	modulusLength: 2048,
})

// use the public and private keys
// ...



// This is the data we want to encrypt
const data = "my secret data"

const encryptedData = crypto.publicEncrypt(
	{
		key: publicKey,
		padding: crypto.constants.RSA_PKCS1_OAEP_PADDING,
		oaepHash: "sha512",
	},
	// We convert the data string to a buffer using `Buffer.from`
	Buffer.from(data)
)

// The encrypted data is in the form of bytes, so we print it in base64 format
// so that it's displayed in a more readable form
console.log("encypted data: ", encryptedData.toString("base64"))



const decryptedData = crypto.privateDecrypt(
	{
		key: privateKey,
		// In order to decrypt the data, we need to specify the
		// same hashing function and padding scheme that we used to
		// encrypt the data in the previous step
		padding: crypto.constants.RSA_PKCS1_OAEP_PADDING,
		oaepHash: "sha512",
	},
	encryptedData
)

// The decrypted data is of the Buffer type, which we can convert to a
// string to reveal the original data
console.log("decrypted data: ", decryptedData.toString())






// Create some sample data that we want to sign
const verifiableData = "this need to be verified"

// The signature method takes the data we want to sign, the
// hashing algorithm, and the padding scheme, and generates
// a signature in the form of bytes
const signature = crypto.sign("sha512", Buffer.from(verifiableData), {
	key: privateKey,
	padding: crypto.constants.RSA_PKCS1_PSS_PADDING,
})

console.log(signature.toString("base64"))

// To verify the data, we provide the same hashing algorithm and
// padding scheme we provided to generate the signature, along
// with the signature itself, the data that we want to
// verify against the signature, and the public key
const isVerified = crypto.verify(
	"sha512",
	Buffer.from(verifiableData),
	{
		key: publicKey,
		padding: crypto.constants.RSA_PKCS1_PSS_PADDING,
	},
	signature
)

// isVerified should be `true` if the signature is valid
console.log("signature verified: ", isVerified)

Example 2: Encryption RSA, JavaScript

<script type="text/javascript">
    $(function () {

        //Change the key size value for new keys
        $(".change-key-size").each(function (index, value) {
            var el = $(value);
            var keySize = el.attr('data-value');
            el.click(function (e) {
                var button = $('#key-size');
                button.attr('data-value', keySize);
                button.html(keySize + ' bit <span class="caret"></span>');
                e.preventDefault();
            });
        });

        // Execute when they click the button.
        $('#execute').click(function () {

            // Create the encryption object.
            var crypt = new JSEncrypt();

            // Set the private.
            crypt.setPrivateKey($('#privkey').val());
            //return;
            // If no public key is set then set it here...
            var pubkey = $('#pubkey').val();
            if (!pubkey) {
                $('#pubkey').val(crypt.getPublicKey());
            }

            // Get the input and crypted values.
            var input = $('#input').val();
            var crypted = $('#crypted').val();

            // Alternate the values.
            if (input) {
                $('#crypted').val(crypt.encrypt(input));
                $('#input').val('');
            }
            else if (crypted) {
                var decrypted = crypt.decrypt(crypted);
                if (!decrypted)
                    decrypted = 'This is a test!';
                $('#input').val(decrypted);
                $('#crypted').val('');
            }
        });

        var generateKeys = function () {
            var sKeySize = $('#key-size').attr('data-value');
            var keySize = parseInt(sKeySize);
            var crypt = new JSEncrypt({ default_key_size: keySize });
            var async = $('#async-ck').is(':checked');
            var dt = new Date();
            var time = -(dt.getTime());
            if (async) {
                $('#time-report').text('.');
                var load = setInterval(function () {
                    var text = $('#time-report').text();
                    $('#time-report').text(text + '.');
                }, 500);
                crypt.getKey(function () {
                    clearInterval(load);
                    dt = new Date();
                    time += (dt.getTime());
                    $('#time-report').text('Generated in ' + time + ' ms');
                    $('#privkey').val(crypt.getPrivateKey());
                    $('#pubkey').val(crypt.getPublicKey());
                });
                return;
            }
            crypt.getKey();
            dt = new Date();
            time += (dt.getTime());
            $('#time-report').text('Generated in ' + time + ' ms');
            $('#privkey').val(crypt.getPrivateKey());
            $('#pubkey').val(crypt.getPublicKey());
        };

        // If they wish to generate new keys.
        $('#generate').click(generateKeys);
        generateKeys();
    });
</script>