Encrypting data with a public key in Node.js

Question

I need to encrypt a string using a public key (.pem file), and then sign it using a private key (also a .pem).

I am loading the .pem files fine:

publicCert = fs.readFileSync(publicCertFile).toString(); 

But after hours of scouring Google, I can't seem to find a way to encrypt data using the public key. In PHP I simply call openssl_public_encrypt(), but I don't see any corresponding function in Node.js or in any modules.

Answer 1

A library is not necessary. Enter crypto.

Here's a janky little module you could use to encrypt/decrypt strings with RSA keys:

var crypto = require("crypto"); var path = require("path"); var fs = require("fs");  var encryptStringWithRsaPublicKey = function(toEncrypt, relativeOrAbsolutePathToPublicKey) {     var absolutePath = path.resolve(relativeOrAbsolutePathToPublicKey);     var publicKey = fs.readFileSync(absolutePath, "utf8");     var buffer = Buffer.from(toEncrypt);     var encrypted = crypto.publicEncrypt(publicKey, buffer);     return encrypted.toString("base64"); };  var decryptStringWithRsaPrivateKey = function(toDecrypt, relativeOrAbsolutePathtoPrivateKey) {     var absolutePath = path.resolve(relativeOrAbsolutePathtoPrivateKey);     var privateKey = fs.readFileSync(absolutePath, "utf8");     var buffer = Buffer.from(toDecrypt, "base64");     var decrypted = crypto.privateDecrypt(privateKey, buffer);     return decrypted.toString("utf8"); };  module.exports = {     encryptStringWithRsaPublicKey: encryptStringWithRsaPublicKey,     decryptStringWithRsaPrivateKey: decryptStringWithRsaPrivateKey } 

I would recommend not using synchronous fs methods where possible, and you could use promises to make this better, but for simple use cases this is the approach that I have seen work and would take.