From f15e09840ae114753d7fe2e323c0dced2c5afc13 Mon Sep 17 00:00:00 2001
From: Vladislav Hristov <vladislav.hristov@ecollect.net>
Date: Fri, 1 Nov 2019 13:44:29 +0200
Subject: [PATCH] add: add Key class to manage a single key

---
 lib/keymanagers/Key.js | 137 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 lib/keymanagers/Key.js

diff --git a/lib/keymanagers/Key.js b/lib/keymanagers/Key.js
new file mode 100644
index 0000000..1f17e78
--- /dev/null
+++ b/lib/keymanagers/Key.js
@@ -0,0 +1,137 @@
+'use strict';
+
+const {
+	pki: {
+		rsa,
+		publicKeyToPem,
+		privateKeyToPem,
+		publicKeyFromPem,
+		privateKeyFromPem,
+	},
+	jsbn: {
+		BigInteger,
+	},
+} = require('node-forge');
+
+const getKeyType = (str) => {
+	const matches = str.match(/(PRIVATE|PUBLIC) KEY/);
+	if (!matches)
+		return null;
+	return matches[1].toLowerCase();
+};
+
+const keyFromPem = (pem) => {
+	const type = getKeyType(pem);
+	const isPublic = type === 'public';
+	const key = isPublic ? publicKeyFromPem(pem) : privateKeyFromPem(pem);
+
+	return {
+		isPublic,
+		key,
+	};
+};
+
+/**
+ * Creates a public key from modulus and exponent
+ * @param {Buffer} mod - the modulus
+ * @param {Buffer} exp - the exponent
+ */
+const keyFromModAndExp = (mod, exp) => {
+	const bnMod = new BigInteger(mod.toString('hex'), 16);
+	const bnExp = new BigInteger(exp.toString('hex'), 16);
+
+	return {
+		key: rsa.setPublicKey(bnMod, bnExp),
+		isPublic: true,
+	};
+};
+
+module.exports = class Key {
+	constructor({
+		pem = null, mod = null, exp = null, size = 2048,
+	} = {}) {
+		// generate new private key
+		if (!pem && !mod && !exp) {
+			const keyPair = rsa.generateKeyPair(size);
+
+			this.keyIsPublic = false;
+			this.privateKey = keyPair.privateKey;
+			this.publicKey = keyPair.publicKey;
+
+			return;
+		}
+
+		// new key from pem string
+		if (pem) {
+			const { key, isPublic } = keyFromPem(pem);
+
+			this.keyIsPublic = isPublic;
+			this.privateKey = isPublic ? null : key;
+			this.publicKey = isPublic ? key : null;
+
+			return;
+		}
+
+		// new key from mod and exp
+		if (mod && exp) {
+			const { key, isPublic } = keyFromModAndExp(mod, exp);
+
+			this.keyIsPublic = isPublic;
+			this.privateKey = isPublic ? null : key;
+			this.publicKey = isPublic ? key : null;
+
+			return;
+		}
+
+		// not good
+		throw new Error(`Can not create key without ${!mod ? 'modulus' : 'exponent'}.`);
+	}
+
+	static generate(size = 2048) {
+		return new Key({ size });
+	}
+
+	static importKey({ mod, exp }) {
+		return new Key({ mod, exp });
+	}
+
+	n(to = 'buff') {
+		const key = this.keyIsPublic ? this.publicKey : this.privateKey;
+		const keyN = Buffer.from(key.n.toByteArray());
+
+		return to === 'hex' ? keyN.toString('hex', 1) : keyN;
+	}
+
+	e(to = 'buff') {
+		const key = this.keyIsPublic ? this.publicKey : this.privateKey;
+		const eKey = Buffer.from(key.e.toByteArray());
+
+		return to === 'hex'
+			? eKey.toString('hex')
+			: eKey;
+	}
+
+	d() {
+		if (this.keyIsPublic)
+			throw new Error('Can not get d component out of public key.');
+
+		return Buffer.from(this.privateKey.d.toByteArray());
+	}
+
+	isPrivate() {
+		return !this.keyIsPublic;
+	}
+
+	isPublic() {
+		return this.keyIsPublic;
+	}
+
+	// eslint-disable-next-line class-methods-use-this
+	size() {
+		return 2048;
+	}
+
+	toPem() {
+		return this.keyIsPublic ? publicKeyToPem(this.publicKey) : privateKeyToPem(this.privateKey);
+	}
+}