An example of RSA Encryption implemented in Node.js

rsa.js

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,
})

console.log(
	publicKey.export({
		type: "pkcs1",
		format: "pem",
	}),

	privateKey.export({
		type: "pkcs1",
		format: "pem",
	})
)

// 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: "sha256",
	},
	// 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: "sha256",
	},
	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("sha256", 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(
	"sha256",
	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)

hi , my module is angular js, Can i run this in angular

thank you so much i gave you credit in my dapp

how to store a public and private key in a single-string and later use it in encrypt/decrypt logic

what i had in mind is this

const publicKey = "";

const encryptedData = crypto.publicEncrypt(
	{
		key: Buffer.from(publicKey),
......
}

tried using this but got error : Error: error:0909006C:PEM routines:get_name:no start line

Hi @sohamkamani,
I am new in node.js. Can you please share your package.json file or let me know what module to be installed via npm to make your code working. What module to install for - const crypto = require("crypto")? When I searched https://www.npmjs.com/ for crypto, I didn't find anything matching exactly. Please share the URL of the module name in npmjs.com if possible.

@mainakaich crypto is a native module from Node.
https://nodejs.org/api/crypto.html