node-ebics-client/lib/Signer.js

'use strict';

// const crypto = require('crypto');
const Crypto = require('./crypto/Crypto');

const { DOMParser, XMLSerializer } = require('xmldom');
const xpath = require('xpath');
const C14n = require('xml-crypto/lib/c14n-canonicalization').C14nCanonicalization;


module.exports = class Signer {
	/**
	 * Contructor.
	 *
	 * @param {Keys} keys
	 * @param {String} data
	 */
	constructor(keys, data) {
		/**
		 * Keys to operate with
		 *
		 * @type {Keys}
		 */
		this.keys = keys;

		/**
		 * Request data - generated xml
		 *
		 * @type {String}
		 */
		this.doc = new DOMParser().parseFromString(data, 'text/xml');
	}

	digest() {
		// get the xml node, where the digested value is supposed to be
		const nodeDigestValue = this.doc.getElementsByTagName('ds:DigestValue')[0];

		// canonicalize the node that has authenticate='true' attribute
		const contentToDigest = xpath.select("//*[@authenticate='true']", this.doc)
			.map(x => new C14n().process(x)).join('');

		// fix the canonicalization
		const fixedContent = contentToDigest.replace(/xmlns="urn:org:ebics:H004"/g, 'xmlns="urn:org:ebics:H004" xmlns:ds="http://www.w3.org/2000/09/xmldsig#"');

		if (nodeDigestValue)
			nodeDigestValue.textContent = Crypto.digestWithHash(fixedContent).toString('base64').trim();
	}

	sign() {
		const nodeSignatureValue = this.doc.getElementsByTagName('ds:SignatureValue')[0];

		if (nodeSignatureValue) {
			const select = xpath.useNamespaces({ ds: 'http://www.w3.org/2000/09/xmldsig#' });
			const contentToSign = (new C14n().process(select('//ds:SignedInfo', this.doc)[0])).replace('xmlns:ds="http://www.w3.org/2000/09/xmldsig#"', 'xmlns="urn:org:ebics:H004" xmlns:ds="http://www.w3.org/2000/09/xmldsig#"');

			nodeSignatureValue.textContent = Crypto.privateSign(this.keys.x(), contentToSign); // this.keys.x().key.sign(contentToSign, 'base64');
		}
	}

	toXML() {
		return new XMLSerializer().serializeToString(this.doc);
	}
};