nodejs tls hpkp

tls-hpkp.js

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

var options = {
	host: "test.dev",
	port: 8888,
	ca: [fs.readFileSync("cert.pem"), fs.readFileSync("cert2.pem")],
};

// cert fingerprint 99:5B:7B:AD:28:F4:7C:72:96:6C:24:9E:6A:63:A4:B0:AF:04:E5:43
// openssl x509 -in cert.pem -outform DER | shasum

// hpkp base64 wh8TAnmj3IABejy1snFQdaqCjkFm73iArCmXKHGJGKc=
// hpkp: openssl x509 -in cert.pem -pubkey -noout | openssl rsa -pubin -outform der | openssl dgst -sha256 -binary | openssl enc -base64

function rsaPublicKeyDer(modulus_b64, exponent_b64) {
	function prepadSigned(hexStr) {
		msb = hexStr[0]
		if (
			(msb>='8' && msb<='9') || 
			(msb>='a' && msb<='f') || 
			(msb>='A'&&msb<='F')) {
			return '00'+hexStr;
		} else {
			return hexStr;
		}
	}

	function toHex(number) {
		var nstr = number.toString(16)
		if (nstr.length%2==0) return nstr
		return '0'+nstr
	}

	// encode ASN.1 DER length field
	// if <=127, short form
	// if >=128, long form
	function encodeLengthHex(n) {
		if (n<=127) return toHex(n)
		else {
			n_hex = toHex(n)
			length_of_length_byte = 128 + n_hex.length/2 // 0x80+numbytes
			return toHex(length_of_length_byte)+n_hex
		}
	}

	var modulus = new Buffer(modulus_b64,'base64');
	var exponent = new Buffer(exponent_b64, 'base64');

	var modulus_hex = modulus.toString('hex')
	var exponent_hex = exponent.toString('hex')

	modulus_hex = prepadSigned(modulus_hex)
	exponent_hex = prepadSigned(exponent_hex)

	var modlen = modulus_hex.length/2
	var explen = exponent_hex.length/2

	var encoded_modlen = encodeLengthHex(modlen)
	var encoded_explen = encodeLengthHex(explen)
	var encoded_pubkey = '30' + 
		encodeLengthHex(
			modlen + 
			explen + 
			encoded_modlen.length/2 + 
			encoded_explen.length/2 + 2
		) + 
		'02' + encoded_modlen + modulus_hex +
		'02' + encoded_explen + exponent_hex;

	var seq2 = 
		'30 0d ' +
		  '06 09 2a 86 48 86 f7 0d 01 01 01' +
		  '05 00 ' +
		'03' + encodeLengthHex(encoded_pubkey.length/2 + 1) +
		'00' + encoded_pubkey;

	seq2 = seq2.replace(/ /g,'');

	var der_hex = '30' + encodeLengthHex(seq2.length/2) + seq2;

	der_hex = der_hex.replace(/ /g, '');

	return new Buffer(der_hex, 'hex');
}

function rsaPublicKeyPem(modulus_b64, exponent_b64) {
	var der = rsaPublicKeyDer(modulus_b64, exponent_b64);
	var der_b64 = der.toString('base64');

	var pem = '-----BEGIN PUBLIC KEY-----\n' 
		+ der_b64.match(/.{1,64}/g).join('\n') 
		+ '\n-----END PUBLIC KEY-----\n';

	return pem
}

function generateHpbkPin(publicKeyDer) {
	return crypto.createHash("sha256").update(publicKeyDer).digest("base64");
}

function validateHpbkPin(peerCertificate, pin) {
	var publicKey = rsaPublicKeyDer(
		new Buffer(peerCertificate.modulus, "hex").toString("base64"),
		new Buffer((peerCertificate.exponent.length % 2 ? "0" : "")+peerCertificate.exponent, "hex").toString("base64")
	);
	
	var hash = generateHpbkPin(publicKey);
	return hash === pin;
}

var socket = tls.connect(options, function (err) {
	console.log("connected");
	
	console.log(socket.getPeerCertificate());
	console.log(socket.getPeerCertificate().modulus);
	console.log(socket.getPeerCertificate().exponent);
	
	console.log(validateHpbkPin(socket.getPeerCertificate(), 'wh8TAnmj3IABejy1snFQdaqCjkFm73iArCmXKHGJGKc='));
	
	process.stdin.pipe(socket);
	process.stdin.resume();
});
socket.setEncoding("utf8");
socket.on("data", function (data) {
	console.log(data);
});