JS - AES 256 crypt/decrypt compatible with 'openssl enc' format - depends on sjcl for SHA256 Raw

aes256-compat-openssl-enc-dec.js

/*
 * AES 256 crypt/decrypt compatible with 'openssl enc' format
 * Depends on sjcl for SHA256: https://bitwiseshiftleft.github.io/sjcl/
 * 
 * Usage:
    <script type="text/javascript" src="sjcl.js"></script>
		<script type="text/javascript" src="this_file.js"></script>
 *
 * Author: Zorro Aka Diego de la Vega
 *
 */

function hexToBin(hex)
{
	var bytes = new Array(hex.length / 2);
	var i = 0;

	for(; i < hex.length; i += 2) {
		bytes[i / 2] = (parseInt(hex.substr(i, 2), 16));
	}
	return bytes;
}

function binToHex(bin)
{
	var hex = "";
	bin.forEach(function(b) {
		hex += ('0' + (b & 0xFF).toString(16)).slice(-2);
	});
	return hex;
}

// EVP_BytesToKey (With Stanford Javascript Crypto Library For SHA256)
// (GitHub = https://github.com/bitwiseshiftleft/sjcl/)
function EVP_BytesToKey(salt, passphrase, nkey, niv)
{
	var md_buf = null;
	var key = [];
	var iv = [];
	var addmd = 0;
	var i = 0;

	while(key.length < nkey || iv.length < niv) {
		var sha = new sjcl.hash.sha256();
		if (addmd) {
			sha.update(md_buf);
		} else {
			addmd++;
		}
		sha.update(passphrase);
		sha.update(salt);
		md_buf = sha.finalize();
		var md_buf2 = sjcl.codec.hex.fromBits(md_buf);
		var md_buf3 = hexToBin(md_buf2);
		md_buf2 = hexToBin(md_buf2);
		if (key.length < nkey) {
			var pos = nkey - key.length;
			for(i = 0; i < pos; i++) {
				key.push(md_buf2[i]);
			}
			md_buf2 = [];
			for(; i < md_buf3.length; i++) {
				md_buf2.push(md_buf3[i]);
			}
		}
		if (iv.length < niv) {
			var diff = niv - iv.length;
			for(i = 0; i < diff; i++) {
				if (i >= md_buf2.length) {
					break;
				}
				iv.push(md_buf2[i]);
			}
		}
	}
	return [key, iv];
}

// AES-CBC Encrypt Function (With window.crypto.subtle.encrypt Function)
// (Doc = https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/encrypt)
const encryptText = async (plainText, password, iv) => {
	const ptUtf8 = new TextEncoder().encode(plainText);
	const pwHash = new Uint8Array(password).buffer;
	const myiv = new Uint8Array(iv);
	const alg = { name: "AES-CBC", iv: myiv };
	const key = await crypto.subtle.importKey('raw', pwHash, alg, false, ['encrypt']);
	return crypto.subtle.encrypt(alg, key, ptUtf8);
}

// AES-CBC Decrypt Function (With window.crypto.subtle.decrypt Function)
// (Doc = https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/decrypt)
const decryptText = async (encBuffer, password, iv) => {
	const pwHash = new Uint8Array(password).buffer;
	const myiv = new Uint8Array(iv);
	const alg = { name: "AES-CBC", iv: myiv };
	const key = await crypto.subtle.importKey('raw', pwHash, alg, false, ['decrypt']);
	return crypto.subtle.decrypt(alg, key, encBuffer);
}


// Set Values
var salt = "\x01\x02\x03\x04\x05\x06\x07\x08"; // TODO Random
var pass = "et";
var data = "toto";
// Get Key/IV
var aKeyIV = EVP_BytesToKey(salt, pass, 32, 16);
console.log("KEY = ", binToHex(aKeyIV[0]))
console.log("IV = ", binToHex(aKeyIV[1]));
// Pad Data
var pad = 16 - data.length % 16;
var i = 0;
for(; i < pad; i++) {
	data += String.fromCharCode(pad);
}
// Encrypt/Decrypt Data
(async () => {
	var enc = await encryptText(data, aKeyIV[0], aKeyIV[1]);
	var ret = new Uint8Array(enc.slice(0, enc.byteLength - 16)); // Remove 16Bytes Because Encrypt '\0'
	var txt = "Salted__" + salt + String.fromCharCode.apply(null, ret);
	console.log("ENC = ", btoa(txt));
	// Decrypt (TODO Base64 Decode, Get Salt...)
	var dec = await decryptText(enc, aKeyIV[0], aKeyIV[1]);
	ret = String.fromCharCode.apply(null, new Uint8Array(dec));
	// Remove Padding
	var i = 0;
	for(i = ret.length; i >= 0; i--) {
		if (ret.charCodeAt(i) > 16) {
			break;
		}
	}
	if (i > 0) {
		txt = ret.substr(0, i + 1);
	} else {
		txt = "";
	}
	console.log("DEC = ", txt);
})();

lovely, thanks a lot for making this 😄