Node.js correct way to make rsa encrypt?

Question

i'm trying to create a WS for make soap request. In the body of the message there is a field that contains an encrypted text. I have the public key to encrypt the text but the only result that i obtain is that the text is not recognized. I use crypto module of node for making request and the text is crypted but i don't know why is not correclty encrypted.

Ps i made the same thing on php with openssl_public_encrypt function and working. But i have to do it in node.js.

Any idea or suggestion? What is different openssl_public_encrypt from crypto.publicEncrypt function?

Here is the encrypt part in node.js:

var crypto = require("crypto");
var fs = require('fs');

fs.readFile("./certificate.pem", 'utf8', function (err, data) {
    var bufferToEncrypt = new Buffer("textToEncrypt");
    var encrypted = crypto.publicEncrypt({"key":data, padding:crypto.RSA_NO_PADDING}, bufferToEncrypt).toString("base64");
    console.log(encrypted);  // length 128
}

The same thing in php:

<?php

    $publicKey = "./certificate.pem";
    $plaintext = "textToEncrypt";

    openssl_public_encrypt($plaintext, $encrypted, $publicKey);

    echo base64_encode($encrypted);   //encrypted string length 128

?>

I don't have the private key for decrypting the text, i only have the public key.

Also notice that the length of the encrypted text (in base64) is the same in php and in node.js.

Answer 1

I guess the padding is your problem. In node.js you specify padding:crypto.RSA_NO_PADDING. When looking up the doc of openssl_public_encrypt() it says that it uses OPENSSL_PKCS1_PADDING by default. Try the following:

var constants = require("constants");
var encrypted = crypto.publicEncrypt({"key":data,
    padding:constants.RSA_PKCS1_PADDING}, bufferToEncrypt).toString("base64");

I have prepared an online demo:

1. Encrypt using node.js
2. copy the resulting string
3. and paste it to $encrypted_encoded on PHP decryption example

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Advise: As a rule of thumb, don't use asymmetric encryption for actual messages. Use it to protect a symmetric key instead. However, your use case might be valid, I just want to state this every time someone talks RSA encryption.