@davidkhala/crypto/X509Certificate.js

## Limitation - node-forge doesn't support ECDSA yet - https://github.com/digitalbazaar/forge/issues/116 - https://github.com/digitalbazaar/forge/issues/532 - https://github.com/digitalbazaar/forge/issues/671 - https://github.com/digitalbazaar/for

import {X509} from 'jsrsasign';

export default class X509Certificate {
	constructor(pem) {
		const x509 = new X509();
		x509.readCertPEM(pem);
		this.x509 = x509;
	}

	/**
	 *
	 * @param {boolean} [asString]
	 * @return {string|Object}
	 */
	getSubject(asString) {
		const subject = this.x509.getSubject();
		if (asString) {
			return subject.str;
		}
		const {array} = subject;
		const result = {};
		for (const [item] of array) {
			const {type, value} = item;
			result[type] = value;
		}
		return result;
	}

	// authorityKeyIdentifier (AKI)
	get authorityKeyIdentifier() {
		const authorityKeyIdentifier = this.x509.getExtAuthorityKeyIdentifier();
		// it is possible that certificate does not contain Authority Key Identifier
		if (!authorityKeyIdentifier) {
			return undefined;
		}
		return authorityKeyIdentifier.kid.hex;
	}

	// serial number
	get serial() {
		return this.x509.getSerialNumberHex();
	}

}