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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>StatiCrypt: Password protect static HTML</title>
<meta name="description" content="" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<link
rel="stylesheet"
type="text/css"
href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css"
integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u"
crossorigin="anonymous"
/>
<style>
a.no-style {
color: inherit;
text-decoration: inherit;
}
body {
font-size: 16px;
}
label.no-style {
font-weight: normal;
}
@media screen and (-webkit-min-device-pixel-ratio:0) {
.staticrypt-form input[type="password"],
input[type="text"] {
font-size: 16px;
}
}
</style>
</head>
<body>
<div class="container">
<div class="row">
<div class="col-xs-12">
<h1>
StatiCrypt
<div class="pull-right">
<iframe
src="https://ghbtns.com/github-btn.html?user=robinmoisson&repo=staticrypt&type=star&size=large"
frameborder="0"
scrolling="0"
width="80px"
height="30px"
></iframe>
<iframe
src="https://ghbtns.com/github-btn.html?user=robinmoisson&repo=staticrypt&type=fork&size=large"
frameborder="0"
scrolling="0"
width="80px"
height="30px"
></iframe>
</div>
<br />
<small>Password protect a static HTML page</small>
</h1>
<p>
StatiCrypt uses AES-256 with WebCrypto to encrypt your html string with your long password, in
your browser (client side).
</p>
<p>
Download your encrypted string in a HTML page with a password prompt you can upload anywhere
(see <a target="_blank" href="example/encrypted/example.html">example</a>).
</p>
<p>
The tool is also available as
<a href="https://npmjs.com/package/staticrypt">a CLI on NPM</a> and is
<a href="https://github.com/robinmoisson/staticrypt">open source on GitHub</a>.
</p>
<br />
<h4>
<a class="no-style" id="toggle-concept" href="#">
<span id="toggle-concept-sign">►</span> HOW IT WORKS
</a>
</h4>
<div id="concept" class="hidden">
<p>
<b class="text-danger">Disclaimer</b> if you are an at-risk activist, or have extra
sensitive banking data, you should probably use something else!
</p>
<p>
StatiCrypt generates a static, password protected page that can be decrypted in-browser:
just send or upload the generated page to a place serving static content (github pages, for
example) and you're done: the javascript will prompt users for password, decrypt the page
and load your HTML.
</p>
<p>
The page is encrypted with AES-256 in CBC mode (see why this mode is appropriate for
StatiCrypt in
<a href="https://github.com/robinmoisson/staticrypt/issues/19">#19</a>). The password is
hashed with PBKDF2 (599k iterations with SHA-256, plus 1k with SHA-1 for legacy reasons (see
<a href="https://github.com/robinmoisson/staticrypt/issues/159">#159</a>), for the added
<a
href="https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html#pbkdf2"
>recommended total</a
>
of 600k) and used to encrypt the page.
</p>
<p>
It basically encrypts your page and puts everything with a user-friendly way to use a
password in the new file. AES-256 is state of the art but
<b
>brute-force/dictionary attacks would be easy to do at a really fast pace: use a long,
unusual password!</b
>
<br />
=> To be safe, we recommend 16+ alphanum characters, and using a password manager like the
open-source <a href="http://bitwarden.com">Bitwarden</a>.
</p>
<p>
Feel free to contribute or report any thought to the
<a href="https://github.com/robinmoisson/staticrypt">GitHub project</a>.
</p>
</div>
<br />
</div>
</div>
<div class="row">
<div class="col-xs-12">
<form id="encrypt_form">
<div class="form-group">
<label for="password">Password</label>
<input
type="password"
class="form-control"
id="password"
placeholder="Password (choose a long one!)"
/>
</div>
<div class="form-group">
<label for="unencrypted_html">HTML/string to encrypt</label>
<textarea
class="form-control"
id="unencrypted_html"
placeholder="<html><head>..."
rows="5"
></textarea>
</div>
<div class="form-group">
<label class="no-style">
<input type="checkbox" id="remember" checked />
Add "Remember me" checkbox (append <code>#staticrypt_logout</code> to your URL to
logout)
<small>
<abbr
class="text-muted"
title='The password will be stored in clear text in the browser's localStorage upon entry by the user. See "More options" to set the expiration (default: none)'
>
(?)
</abbr>
</small>
</label>
</div>
<p>
<a href="#" id="toggle-extra-option">+ More options</a>
</p>
<div id="extra-options" class="hidden">
<div class="form-group">
<label for="template_title">Page title</label>
<input
type="text"
class="form-control"
id="template_title"
placeholder="Default: 'Protected Page'"
/>
</div>
<div class="form-group">
<label for="template_instructions">Instructions to display the user</label>
<textarea
class="form-control"
id="template_instructions"
placeholder="Default: nothing."
></textarea>
</div>
<div class="form-group">
<label for="template_placeholder">Password input placeholder</label>
<input
type="text"
class="form-control"
id="template_placeholder"
placeholder="Default: 'Password'"
/>
</div>
<div class="form-group">
<label for="template_remember">"Remember me" checkbox label</label>
<input
type="text"
class="form-control"
id="template_remember"
placeholder="Default: 'Remember me'"
/>
</div>
<div class="form-group">
<label for="remember_in_days">"Remember me" expiration in days</label>
<input
type="number"
class="form-control"
id="remember_in_days"
step="any"
placeholder="Default: 0 (no expiration)"
/>
<small class="form-text text-muted">
After this many days, the user will have to enter the password again. Leave empty or
set to 0 for no expiration.
</small>
</div>
<div class="form-group">
<label for="template_button">Decrypt button label</label>
<input
type="text"
class="form-control"
id="template_button"
placeholder="Default: 'DECRYPT'"
/>
</div>
<div class="form-group">
<label for="template_color_primary">Primary color (button, ...)</label>
<input
type="text"
class="form-control"
id="template_color_primary"
placeholder="Default: '#4CAF50'"
/>
</div>
<div class="form-group">
<label for="template_color_secondary">Secondary color (background, ...)</label>
<input
type="text"
class="form-control"
id="template_color_secondary"
placeholder="Default: '#76B852'"
/>
</div>
</div>
<button class="btn btn-primary pull-right" type="submit">
Generate password protected HTML
</button>
</form>
</div>
</div>
<div class="row mb-5">
<div class="col-xs-12">
<h2>Encrypted HTML</h2>
<p>
<a
class="btn btn-success download"
download="encrypted.html"
id="download-link"
disabled="disabled"
>Download html file with password prompt</a
>
</p>
<pre id="encrypted_html_display">Your encrypted string</pre>
</div>
</div>
</div>
<script src="https://cdn.ckeditor.com/4.7.0/standard/ckeditor.js"></script>
<script id="cryptoEngine">
window.cryptoEngine = ((function(){
const exports = {};
const { subtle } = crypto;
const IV_BITS = 16 * 8;
const HEX_BITS = 4;
const ENCRYPTION_ALGO = "AES-CBC";
/**
* Translates between utf8 encoded hexadecimal strings
* and Uint8Array bytes.
*/
const HexEncoder = {
/**
* hex string -> bytes
* @param {string} hexString
* @returns {Uint8Array}
*/
parse: function (hexString) {
if (hexString.length % 2 !== 0) throw "Invalid hexString";
const arrayBuffer = new Uint8Array(hexString.length / 2);
for (let i = 0; i < hexString.length; i += 2) {
const byteValue = parseInt(hexString.substring(i, i + 2), 16);
if (isNaN(byteValue)) {
throw "Invalid hexString";
}
arrayBuffer[i / 2] = byteValue;
}
return arrayBuffer;
},
/**
* bytes -> hex string
* @param {Uint8Array} bytes
* @returns {string}
*/
stringify: function (bytes) {
const hexBytes = [];
for (let i = 0; i < bytes.length; ++i) {
let byteString = bytes[i].toString(16);
if (byteString.length < 2) {
byteString = "0" + byteString;
}
hexBytes.push(byteString);
}
return hexBytes.join("");
},
};
/**
* Translates between utf8 strings and Uint8Array bytes.
*/
const UTF8Encoder = {
parse: function (str) {
return new TextEncoder().encode(str);
},
stringify: function (bytes) {
return new TextDecoder().decode(bytes);
},
};
/**
* Salt and encrypt a msg with a password.
*/
async function encrypt(msg, hashedPassword) {
// Must be 16 bytes, unpredictable, and preferably cryptographically random. However, it need not be secret.
// https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/encrypt#parameters
const iv = crypto.getRandomValues(new Uint8Array(IV_BITS / 8));
const key = await subtle.importKey("raw", HexEncoder.parse(hashedPassword), ENCRYPTION_ALGO, false, ["encrypt"]);
const encrypted = await subtle.encrypt(
{
name: ENCRYPTION_ALGO,
iv: iv,
},
key,
UTF8Encoder.parse(msg)
);
// iv will be 32 hex characters, we prepend it to the ciphertext for use in decryption
return HexEncoder.stringify(iv) + HexEncoder.stringify(new Uint8Array(encrypted));
}
exports.encrypt = encrypt;
/**
* Decrypt a salted msg using a password.
*
* @param {string} encryptedMsg
* @param {string} hashedPassword
* @returns {Promise<string>}
*/
async function decrypt(encryptedMsg, hashedPassword) {
const ivLength = IV_BITS / HEX_BITS;
const iv = HexEncoder.parse(encryptedMsg.substring(0, ivLength));
const encrypted = encryptedMsg.substring(ivLength);
const key = await subtle.importKey("raw", HexEncoder.parse(hashedPassword), ENCRYPTION_ALGO, false, ["decrypt"]);
const outBuffer = await subtle.decrypt(
{
name: ENCRYPTION_ALGO,
iv: iv,
},
key,
HexEncoder.parse(encrypted)
);
return UTF8Encoder.stringify(new Uint8Array(outBuffer));
}
exports.decrypt = decrypt;
/**
* Salt and hash the password so it can be stored in localStorage without opening a password reuse vulnerability.
*
* @param {string} password
* @param {string} salt
* @returns {Promise<string>}
*/
async function hashPassword(password, salt) {
// we hash the password in multiple steps, each adding more iterations. This is because we used to allow less
// iterations, so for backward compatibility reasons, we need to support going from that to more iterations.
let hashedPassword = await hashLegacyRound(password, salt);
hashedPassword = await hashSecondRound(hashedPassword, salt);
return hashThirdRound(hashedPassword, salt);
}
exports.hashPassword = hashPassword;
/**
* This hashes the password with 1k iterations. This is a low number, we need this function to support backwards
* compatibility.
*
* @param {string} password
* @param {string} salt
* @returns {Promise<string>}
*/
function hashLegacyRound(password, salt) {
return pbkdf2(password, salt, 1000, "SHA-1");
}
exports.hashLegacyRound = hashLegacyRound;
/**
* Add a second round of iterations. This is because we used to use 1k, so for backwards compatibility with
* remember-me/autodecrypt links, we need to support going from that to more iterations.
*
* @param hashedPassword
* @param salt
* @returns {Promise<string>}
*/
function hashSecondRound(hashedPassword, salt) {
return pbkdf2(hashedPassword, salt, 14000, "SHA-256");
}
exports.hashSecondRound = hashSecondRound;
/**
* Add a third round of iterations to bring total number to 600k. This is because we used to use 1k, then 15k, so for
* backwards compatibility with remember-me/autodecrypt links, we need to support going from that to more iterations.
*
* @param hashedPassword
* @param salt
* @returns {Promise<string>}
*/
function hashThirdRound(hashedPassword, salt) {
return pbkdf2(hashedPassword, salt, 585000, "SHA-256");
}
exports.hashThirdRound = hashThirdRound;
/**
* Salt and hash the password so it can be stored in localStorage without opening a password reuse vulnerability.
*
* @param {string} password
* @param {string} salt
* @param {int} iterations
* @param {string} hashAlgorithm
* @returns {Promise<string>}
*/
async function pbkdf2(password, salt, iterations, hashAlgorithm) {
const key = await subtle.importKey("raw", UTF8Encoder.parse(password), "PBKDF2", false, ["deriveBits"]);
const keyBytes = await subtle.deriveBits(
{
name: "PBKDF2",
hash: hashAlgorithm,
iterations,
salt: UTF8Encoder.parse(salt),
},
key,
256
);
return HexEncoder.stringify(new Uint8Array(keyBytes));
}
function generateRandomSalt() {
const bytes = crypto.getRandomValues(new Uint8Array(128 / 8));
return HexEncoder.stringify(new Uint8Array(bytes));
}
exports.generateRandomSalt = generateRandomSalt;
async function signMessage(hashedPassword, message) {
const key = await subtle.importKey(
"raw",
HexEncoder.parse(hashedPassword),
{
name: "HMAC",
hash: "SHA-256",
},
false,
["sign"]
);
const signature = await subtle.sign("HMAC", key, UTF8Encoder.parse(message));
return HexEncoder.stringify(new Uint8Array(signature));
}
exports.signMessage = signMessage;
function getRandomAlphanum() {
const possibleCharacters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
let byteArray;
let parsedInt;
// Keep generating new random bytes until we get a value that falls
// within a range that can be evenly divided by possibleCharacters.length
do {
byteArray = crypto.getRandomValues(new Uint8Array(1));
// extract the lowest byte to get an int from 0 to 255 (probably unnecessary, since we're only generating 1 byte)
parsedInt = byteArray[0] & 0xff;
} while (parsedInt >= 256 - (256 % possibleCharacters.length));
// Take the modulo of the parsed integer to get a random number between 0 and totalLength - 1
const randomIndex = parsedInt % possibleCharacters.length;
return possibleCharacters[randomIndex];
}
/**
* Generate a random string of a given length.
*
* @param {int} length
* @returns {string}
*/
function generateRandomString(length) {
let randomString = "";
for (let i = 0; i < length; i++) {
randomString += getRandomAlphanum();
}
return randomString;
}
exports.generateRandomString = generateRandomString;
return exports;
})());
</script>
<script id="codec">
window.codec = ((function(){
const exports = {};
/**
* Initialize the codec with the provided cryptoEngine - this return functions to encode and decode messages.
*
* @param cryptoEngine - the engine to use for encryption / decryption
*/
function init(cryptoEngine) {
const exports = {};
/**
* Top-level function for encoding a message.
* Includes password hashing, encryption, and signing.
*
* @param {string} msg
* @param {string} password
* @param {string} salt
*
* @returns {string} The encoded text
*/
async function encode(msg, password, salt) {
const hashedPassword = await cryptoEngine.hashPassword(password, salt);
const encrypted = await cryptoEngine.encrypt(msg, hashedPassword);
// we use the hashed password in the HMAC because this is effectively what will be used a password (so we can store
// it in localStorage safely, we don't use the clear text password)
const hmac = await cryptoEngine.signMessage(hashedPassword, encrypted);
return hmac + encrypted;
}
exports.encode = encode;
/**
* Encode using a password that has already been hashed. This is useful to encode multiple messages in a row, that way
* we don't need to hash the password multiple times.
*
* @param {string} msg
* @param {string} hashedPassword
*
* @returns {string} The encoded text
*/
async function encodeWithHashedPassword(msg, hashedPassword) {
const encrypted = await cryptoEngine.encrypt(msg, hashedPassword);
// we use the hashed password in the HMAC because this is effectively what will be used a password (so we can store
// it in localStorage safely, we don't use the clear text password)
const hmac = await cryptoEngine.signMessage(hashedPassword, encrypted);
return hmac + encrypted;
}
exports.encodeWithHashedPassword = encodeWithHashedPassword;
/**
* Top-level function for decoding a message.
* Includes signature check and decryption.
*
* @param {string} signedMsg
* @param {string} hashedPassword
* @param {string} salt
* @param {int} backwardCompatibleAttempt
* @param {string} originalPassword
*
* @returns {Object} {success: true, decoded: string} | {success: false, message: string}
*/
async function decode(signedMsg, hashedPassword, salt, backwardCompatibleAttempt = 0, originalPassword = "") {
const encryptedHMAC = signedMsg.substring(0, 64);
const encryptedMsg = signedMsg.substring(64);
const decryptedHMAC = await cryptoEngine.signMessage(hashedPassword, encryptedMsg);
if (decryptedHMAC !== encryptedHMAC) {
// we have been raising the number of iterations in the hashing algorithm multiple times, so to support the old
// remember-me/autodecrypt links we need to try bringing the old hashes up to speed.
originalPassword = originalPassword || hashedPassword;
if (backwardCompatibleAttempt === 0) {
const updatedHashedPassword = await cryptoEngine.hashThirdRound(originalPassword, salt);
return decode(signedMsg, updatedHashedPassword, salt, backwardCompatibleAttempt + 1, originalPassword);
}
if (backwardCompatibleAttempt === 1) {
let updatedHashedPassword = await cryptoEngine.hashSecondRound(originalPassword, salt);
updatedHashedPassword = await cryptoEngine.hashThirdRound(updatedHashedPassword, salt);
return decode(signedMsg, updatedHashedPassword, salt, backwardCompatibleAttempt + 1, originalPassword);
}
return { success: false, message: "Signature mismatch" };
}
return {
success: true,
decoded: await cryptoEngine.decrypt(encryptedMsg, hashedPassword),
};
}
exports.decode = decode;
return exports;
}
exports.init = init;
return exports;
})());
</script>
<script id="formater">
window.formater = ((function(){
const exports = {};
/**
* Replace the variable in template tags, between '/*[|variable|]* /0' (without the space in '* /0', ommiting it would
* break this comment), with the provided data.
*
* This weird format is so that we have something that doesn't break JS parser in the template files (it understands it
* as '0'), so we can still use auto-formatting. The auto-formatter might add a space before the '0', we accept both.
*
* @param {string} templateString
* @param {Object} data
*
* @returns string
*/
function renderTemplate(templateString, data) {
return templateString.replace(/\/\*\[\|\s*(\w+)\s*\|]\*\/\s*0/g, function (_, key) {
if (!data || data[key] === undefined) {
return key;
}
if (typeof data[key] === "object") {
return JSON.stringify(data[key]);
}
return data[key];
});
}
exports.renderTemplate = renderTemplate;
return exports;
})());
</script>
<script id="staticrypt">
window.staticrypt = ((function(){
const exports = {};
const cryptoEngine = ((function(){
const exports = {};
const { subtle } = crypto;
const IV_BITS = 16 * 8;
const HEX_BITS = 4;
const ENCRYPTION_ALGO = "AES-CBC";
/**
* Translates between utf8 encoded hexadecimal strings
* and Uint8Array bytes.
*/
const HexEncoder = {
/**
* hex string -> bytes
* @param {string} hexString
* @returns {Uint8Array}
*/
parse: function (hexString) {
if (hexString.length % 2 !== 0) throw "Invalid hexString";
const arrayBuffer = new Uint8Array(hexString.length / 2);
for (let i = 0; i < hexString.length; i += 2) {
const byteValue = parseInt(hexString.substring(i, i + 2), 16);
if (isNaN(byteValue)) {
throw "Invalid hexString";
}
arrayBuffer[i / 2] = byteValue;
}
return arrayBuffer;
},
/**
* bytes -> hex string
* @param {Uint8Array} bytes
* @returns {string}
*/
stringify: function (bytes) {
const hexBytes = [];
for (let i = 0; i < bytes.length; ++i) {
let byteString = bytes[i].toString(16);
if (byteString.length < 2) {
byteString = "0" + byteString;
}
hexBytes.push(byteString);
}
return hexBytes.join("");
},
};
/**
* Translates between utf8 strings and Uint8Array bytes.
*/
const UTF8Encoder = {
parse: function (str) {
return new TextEncoder().encode(str);
},
stringify: function (bytes) {
return new TextDecoder().decode(bytes);
},
};
/**
* Salt and encrypt a msg with a password.
*/
async function encrypt(msg, hashedPassword) {
// Must be 16 bytes, unpredictable, and preferably cryptographically random. However, it need not be secret.
// https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/encrypt#parameters
const iv = crypto.getRandomValues(new Uint8Array(IV_BITS / 8));
const key = await subtle.importKey("raw", HexEncoder.parse(hashedPassword), ENCRYPTION_ALGO, false, ["encrypt"]);
const encrypted = await subtle.encrypt(
{
name: ENCRYPTION_ALGO,
iv: iv,
},
key,
UTF8Encoder.parse(msg)
);
// iv will be 32 hex characters, we prepend it to the ciphertext for use in decryption
return HexEncoder.stringify(iv) + HexEncoder.stringify(new Uint8Array(encrypted));
}
exports.encrypt = encrypt;
/**
* Decrypt a salted msg using a password.
*
* @param {string} encryptedMsg
* @param {string} hashedPassword
* @returns {Promise<string>}
*/
async function decrypt(encryptedMsg, hashedPassword) {
const ivLength = IV_BITS / HEX_BITS;
const iv = HexEncoder.parse(encryptedMsg.substring(0, ivLength));
const encrypted = encryptedMsg.substring(ivLength);
const key = await subtle.importKey("raw", HexEncoder.parse(hashedPassword), ENCRYPTION_ALGO, false, ["decrypt"]);
const outBuffer = await subtle.decrypt(
{
name: ENCRYPTION_ALGO,
iv: iv,
},
key,
HexEncoder.parse(encrypted)
);
return UTF8Encoder.stringify(new Uint8Array(outBuffer));
}
exports.decrypt = decrypt;
/**
* Salt and hash the password so it can be stored in localStorage without opening a password reuse vulnerability.
*
* @param {string} password
* @param {string} salt
* @returns {Promise<string>}
*/
async function hashPassword(password, salt) {
// we hash the password in multiple steps, each adding more iterations. This is because we used to allow less
// iterations, so for backward compatibility reasons, we need to support going from that to more iterations.
let hashedPassword = await hashLegacyRound(password, salt);
hashedPassword = await hashSecondRound(hashedPassword, salt);
return hashThirdRound(hashedPassword, salt);
}
exports.hashPassword = hashPassword;
/**
* This hashes the password with 1k iterations. This is a low number, we need this function to support backwards
* compatibility.
*
* @param {string} password
* @param {string} salt
* @returns {Promise<string>}
*/
function hashLegacyRound(password, salt) {
return pbkdf2(password, salt, 1000, "SHA-1");
}
exports.hashLegacyRound = hashLegacyRound;
/**
* Add a second round of iterations. This is because we used to use 1k, so for backwards compatibility with
* remember-me/autodecrypt links, we need to support going from that to more iterations.
*
* @param hashedPassword
* @param salt
* @returns {Promise<string>}
*/
function hashSecondRound(hashedPassword, salt) {
return pbkdf2(hashedPassword, salt, 14000, "SHA-256");
}
exports.hashSecondRound = hashSecondRound;
/**
* Add a third round of iterations to bring total number to 600k. This is because we used to use 1k, then 15k, so for
* backwards compatibility with remember-me/autodecrypt links, we need to support going from that to more iterations.
*
* @param hashedPassword
* @param salt
* @returns {Promise<string>}
*/
function hashThirdRound(hashedPassword, salt) {
return pbkdf2(hashedPassword, salt, 585000, "SHA-256");
}
exports.hashThirdRound = hashThirdRound;
/**
* Salt and hash the password so it can be stored in localStorage without opening a password reuse vulnerability.
*
* @param {string} password
* @param {string} salt
* @param {int} iterations
* @param {string} hashAlgorithm
* @returns {Promise<string>}
*/
async function pbkdf2(password, salt, iterations, hashAlgorithm) {
const key = await subtle.importKey("raw", UTF8Encoder.parse(password), "PBKDF2", false, ["deriveBits"]);
const keyBytes = await subtle.deriveBits(
{
name: "PBKDF2",
hash: hashAlgorithm,
iterations,
salt: UTF8Encoder.parse(salt),
},
key,
256
);
return HexEncoder.stringify(new Uint8Array(keyBytes));
}
function generateRandomSalt() {
const bytes = crypto.getRandomValues(new Uint8Array(128 / 8));
return HexEncoder.stringify(new Uint8Array(bytes));
}
exports.generateRandomSalt = generateRandomSalt;
async function signMessage(hashedPassword, message) {
const key = await subtle.importKey(
"raw",
HexEncoder.parse(hashedPassword),
{
name: "HMAC",
hash: "SHA-256",
},
false,
["sign"]
);
const signature = await subtle.sign("HMAC", key, UTF8Encoder.parse(message));
return HexEncoder.stringify(new Uint8Array(signature));
}
exports.signMessage = signMessage;
function getRandomAlphanum() {
const possibleCharacters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
let byteArray;
let parsedInt;
// Keep generating new random bytes until we get a value that falls
// within a range that can be evenly divided by possibleCharacters.length
do {
byteArray = crypto.getRandomValues(new Uint8Array(1));
// extract the lowest byte to get an int from 0 to 255 (probably unnecessary, since we're only generating 1 byte)
parsedInt = byteArray[0] & 0xff;
} while (parsedInt >= 256 - (256 % possibleCharacters.length));
// Take the modulo of the parsed integer to get a random number between 0 and totalLength - 1
const randomIndex = parsedInt % possibleCharacters.length;
return possibleCharacters[randomIndex];
}
/**
* Generate a random string of a given length.
*
* @param {int} length
* @returns {string}
*/
function generateRandomString(length) {
let randomString = "";
for (let i = 0; i < length; i++) {
randomString += getRandomAlphanum();
}
return randomString;
}
exports.generateRandomString = generateRandomString;
return exports;
})());
const codec = ((function(){
const exports = {};
/**
* Initialize the codec with the provided cryptoEngine - this return functions to encode and decode messages.
*
* @param cryptoEngine - the engine to use for encryption / decryption
*/
function init(cryptoEngine) {
const exports = {};
/**
* Top-level function for encoding a message.
* Includes password hashing, encryption, and signing.
*
* @param {string} msg
* @param {string} password
* @param {string} salt
*
* @returns {string} The encoded text
*/
async function encode(msg, password, salt) {
const hashedPassword = await cryptoEngine.hashPassword(password, salt);
const encrypted = await cryptoEngine.encrypt(msg, hashedPassword);
// we use the hashed password in the HMAC because this is effectively what will be used a password (so we can store
// it in localStorage safely, we don't use the clear text password)
const hmac = await cryptoEngine.signMessage(hashedPassword, encrypted);
return hmac + encrypted;
}
exports.encode = encode;
/**
* Encode using a password that has already been hashed. This is useful to encode multiple messages in a row, that way
* we don't need to hash the password multiple times.
*
* @param {string} msg
* @param {string} hashedPassword
*
* @returns {string} The encoded text
*/
async function encodeWithHashedPassword(msg, hashedPassword) {
const encrypted = await cryptoEngine.encrypt(msg, hashedPassword);
// we use the hashed password in the HMAC because this is effectively what will be used a password (so we can store
// it in localStorage safely, we don't use the clear text password)
const hmac = await cryptoEngine.signMessage(hashedPassword, encrypted);
return hmac + encrypted;
}
exports.encodeWithHashedPassword = encodeWithHashedPassword;
/**
* Top-level function for decoding a message.