streams/view/js/crypto.js

function str_rot13 (str) {
  // http://kevin.vanzonneveld.net
  // +   original by: Jonas Raoni Soares Silva (http://www.jsfromhell.com)
  // +   improved by: Ates Goral (http://magnetiq.com)
  // +   bugfixed by: Onno Marsman
  // +   improved by: Rafa? Kukawski (http://blog.kukawski.pl)
  // *     example 1: str_rot13('Kevin van Zonneveld');
  // *     returns 1: 'Xriva ina Mbaariryq'
  // *     example 2: str_rot13('Xriva ina Mbaariryq');
  // *     returns 2: 'Kevin van Zonneveld'
  // *     example 3: str_rot13(33);
  // *     returns 3: '33'
	return (str + '').replace(/[a-z]/gi, function (s) {
		return String.fromCharCode(s.charCodeAt(0) + (s.toLowerCase() < 'n' ? 13 : -13));
	});
}

// Arrays for pluggable encryptors/decryptors

let red_encryptors = new Array();
let red_decryptors = new Array();

async function sodium_encrypt(element) {
	if (!window.sodium) {
		window.sodium = await SodiumPlus.auto();
	}

	if (typeof tinyMCE !== typeof undefined) {
		tinyMCE.triggerSave(false,true);
	}

	let message = $(element).val();

	if (!message) {
		return false;
	}

	let password = prompt(aStr['passphrase']);

	if (!password) {
		return false;
	}

	let hint = bin2hex(prompt(aStr['passhint']));

	let salt = await sodium.randombytes_buf(16);
	let nonce = await sodium.randombytes_buf(24);

	let key = await sodium.crypto_pwhash(
		32,
		password,
		salt,
		sodium.CRYPTO_PWHASH_OPSLIMIT_INTERACTIVE,
		sodium.CRYPTO_PWHASH_MEMLIMIT_INTERACTIVE
	);

	// Message can be a string, buffer, array, etc.
	let ciphertext = await sodium.crypto_secretbox(message, nonce, key);
	delete message, password, key;

	let payload = {
		hint: hint,
		alg: 'XSalsa20',
		salt: await sodium.sodium_bin2hex(salt),
		nonce: await sodium.sodium_bin2hex(nonce),
		ciphertext: await sodium.sodium_bin2hex(ciphertext)
	};

	let val = "[crypt]" + window.btoa(JSON.stringify(payload)) + '[/crypt]';

	$(element).val(val);
}

async function sodium_decrypt(payload, element) {
	let arr = JSON.parse(window.atob(payload));

	if (arr.alg !== 'XSalsa20') {
		alert('Unsupported algorithm');
		return false;
	}

	let password = prompt((arr.hint.length) ? hex2bin(arr.hint) : aStr['passphrase']);

	if (!password) {
		return false;
	}

	let salt = await sodium.sodium_hex2bin(arr.salt);
	let nonce = await sodium.sodium_hex2bin(arr.nonce);
	let ciphertext = await sodium.sodium_hex2bin(arr.ciphertext);

	let key = await sodium.crypto_pwhash(
		32,
		password,
		salt,
		sodium.CRYPTO_PWHASH_OPSLIMIT_INTERACTIVE,
		sodium.CRYPTO_PWHASH_MEMLIMIT_INTERACTIVE
	);

	let decrypted = await sodium.crypto_secretbox_open(ciphertext, nonce, key);
	delete password, key;

	if ($(element).css('display') === 'none' && typeof tinyMCE !== typeof undefined) {
		tinyMCE.activeEditor.setContent(decrypted.toString('utf-8'));
	}
	else {
		$(element).html(decrypted.toString('utf-8'));
	}
}


function hz_encrypt(alg, elem) {
	var enc_text = '';
	var newdiv = '';

	if(typeof tinyMCE !== "undefined")
		tinyMCE.triggerSave(false,true);

	var text = $(elem).val();

	// key and hint need to be localised

	var passphrase = prompt(aStr['passphrase']);
	// let the user cancel this dialogue
	if (passphrase == null)
			return false;
	var enc_key = bin2hex(passphrase);

	// If you don't provide a key you get rot13, which doesn't need a key
	// but consequently isn't secure.  

	if(! enc_key)
		alg = 'rot13';

	if((alg == 'rot13') || (alg == 'triple-rot13'))
		newdiv = "[crypt alg='rot13']" + window.btoa(str_rot13(text)) + '[/crypt]';

	if(alg == 'AES-128-CCM') {

			// This is the prompt we're going to use when the receiver tries to open it.
			// Maybe "Grandma's maiden name" or "our secret place" or something. 

			var enc_hint = bin2hex(prompt(aStr['passhint']));

			enc_text = sjcl.encrypt(enc_key, text);

			encrypted = enc_text.toString();

			newdiv = "[crypt alg='AES-128-CCM' hint='" + enc_hint + "']" + window.btoa(encrypted) + '[/crypt]';
	}

	if((red_encryptors.length) && (! newdiv.length)) {
		for(var i = 0; i < red_encryptors.length; i ++) {
			newdiv = red_encryptors[i](alg,text);
			if(newdiv.length)
				break;
		}
	}
	
	enc_key = '';

	// This might be a comment box on a page with a tinymce editor
	// so check if there is a tinymce editor but also check the display
	// property of our source element - because a tinymce instance
	// will have display "none". If a normal textarea such as in a comment
	// box has display "none" you wouldn't be able to type in it.
	
	if($(elem).css('display') == 'none' && typeof tinyMCE !== "undefined") {
		tinyMCE.activeEditor.setContent(newdiv);
	}
	else {
		$(elem).val(newdiv);
	}

}

function hz_decrypt(alg, hint, text, elem) {

	var dec_text = '';

	text = window.atob(text);

	if(alg == 'rot13' || alg == 'triple-rot13')
		dec_text = str_rot13(text);
	else {
		var enc_key = bin2hex(prompt((hint.length) ? hex2bin(hint) : aStr['passphrase']));
	}

	if(alg == 'AES-128-CCM') {
		dec_text = sjcl.decrypt(enc_key, text);
	}

	if((red_decryptors.length) && (! dec_text.length)) {
		for(var i = 0; i < red_decryptors.length; i ++) {
			dec_text = red_decryptors[i](alg,text,enc_key);
			if(dec_text.length)
				break;
		}
	}

	enc_key = '';

	// Not sure whether to drop this back in the conversation display.
	// It probably needs a lightbox or popup window because any conversation 
	// updates could 
	// wipe out the text and make you re-enter the key if it was in the
	// conversation. For now we do that so you can read it.

	var dec_result = dec_text.toString();
	delete dec_text;

	// incorrect decryptions *usually* but don't always have zero length
	// If the person typo'd let them try again without reloading the page
	// otherwise they'll have no "padlock" to click to try again.

	if(dec_result.length) {
		$(elem).html(b2h(dec_result));
		dec_result = '';
	}
}