feat: allow passwords with length > 73 characters (#8818)

* feat: allow passwords longer than 73 characters

Context: A bcrypt/blowfish limitation means that password length is capped at 72 characters. We can get around this without compromising on security
by hashing all incoming passwords with SHA512, and then sending that to bcrypt.

https://dropbox.tech/security/how-dropbox-securely-stores-your-passwords

* feat: add additional test for passwords > 73 chars

* fix: remove 'password-too-long' error message and all invocations

* test: added test to show that a super long password won't bring down NodeBB

* fix: remove debug log

* Revert "fix: remove 'password-too-long' error message and all invocations"

This reverts commit 1e312bf7ef.

* fix: added back password length checks, but at 512 chars

As processing a large string still uses a lot of memory

src/controllers/authentication.js

@@ -94,7 +94,7 @@ authenticationController.register = async function (req, res) {
 			throw new Error('[[user:change_password_error_match]]');
 		}
 
-		if (userData.password.length > 4096) {
+		if (userData.password.length > 512) {
 			throw new Error('[[error:password-too-long]]');
 		}
 
@@ -357,7 +357,7 @@ authenticationController.localLogin = async function (req, username, password, n
 		return next(new Error('[[error:invalid-password]]'));
 	}
 
-	if (password.length > 4096) {
+	if (password.length > 512) {
 		return next(new Error('[[error:password-too-long]]'));
 	}
 

src/password.js

@@ -1,9 +1,11 @@
 'use strict';
 
 const path = require('path');
-const bcrypt = require('bcryptjs');
+const crypto = require('crypto');
 const util = require('util');
 
+const bcrypt = require('bcryptjs');
+
 const fork = require('./meta/debugFork');
 
 function forkChild(message, callback) {
@@ -19,11 +21,17 @@ function forkChild(message, callback) {
 const forkChildAsync = util.promisify(forkChild);
 
 exports.hash = async function (rounds, password) {
+	password = crypto.createHash('sha512').update(password).digest('hex');
 	return await forkChildAsync({ type: 'hash', rounds: rounds, password: password });
 };
 
-exports.compare = async function (password, hash) {
+exports.compare = async function (password, hash, shaWrapped) {
 	const fakeHash = await getFakeHash();
+
+	if (shaWrapped) {
+		password = crypto.createHash('sha512').update(password).digest('hex');
+	}
+
 	return await forkChildAsync({ type: 'compare', password: password, hash: hash || fakeHash });
 };
 

src/user/create.js

@@ -128,7 +128,10 @@ module.exports = function (User) {
 		}
 		const hash = await User.hashPassword(password);
 		await Promise.all([
-			User.setUserField(uid, 'password', hash),
+			User.setUserFields(uid, {
+				password: hash,
+				'password:shaWrapped': 1,
+			}),
 			User.reset.updateExpiry(uid),
 		]);
 	}

src/user/password.js

@@ -17,7 +17,7 @@ module.exports = function (User) {
 
 	User.isPasswordCorrect = async function (uid, password, ip) {
 		password = password || '';
-		var hashedPassword = await db.getObjectField('user:' + uid, 'password');
+		var { password: hashedPassword, 'password:shaWrapped': shaWrapped } = await db.getObjectFields('user:' + uid, ['password', 'password:shaWrapped']);
 		if (!hashedPassword) {
 			// Non-existant user, submit fake hash for comparison
 			hashedPassword = '';
@@ -25,7 +25,7 @@ module.exports = function (User) {
 
 		User.isPasswordValid(password, 0);
 		await User.auth.logAttempt(uid, ip);
-		const ok = await Password.compare(password, hashedPassword);
+		const ok = await Password.compare(password, hashedPassword, !!parseInt(shaWrapped, 10));
 		if (ok) {
 			await User.auth.clearLoginAttempts(uid);
 		}

src/user/profile.js

@@ -324,6 +324,7 @@ module.exports = function (User) {
 		await Promise.all([
 			User.setUserFields(data.uid, {
 				password: hashedPassword,
+				'password:shaWrapped': 1,
 				rss_token: utils.generateUUID(),
 			}),
 			User.reset.cleanByUid(data.uid),

src/user/reset.js

@@ -70,7 +70,7 @@ UserReset.commit = async function (code, password) {
 
 	const hash = await user.hashPassword(password);
 
-	await user.setUserFields(uid, { password: hash, 'email:confirmed': 1 });
+	await user.setUserFields(uid, { password: hash, 'email:confirmed': 1, 'password:shaWrapped': 1 });
 	await groups.join('verified-users', uid);
 	await groups.leave('unverified-users', uid);
 	await db.deleteObjectField('reset:uid', code);

test/password.js

@@ -0,0 +1,52 @@
+'use strict';
+
+const assert = require('assert');
+const bcrypt = require('bcryptjs');
+
+const password = require('../src/password');
+
+describe('Password', () => {
+	describe('.hash()', () => {
+		it('should return a password hash when called', async () => {
+			const hash = await password.hash(12, 'test');
+			assert(hash.startsWith('$2a$'));
+		});
+	});
+
+	describe('.compare()', async () => {
+		const salt = await bcrypt.genSalt(12);
+
+		it('should correctly compare a password and a hash', async () => {
+			const hash = await password.hash(12, 'test');
+			const match = await password.compare('test', hash, true);
+			assert(match);
+		});
+
+		it('should correctly handle comparison with no sha wrapping of the input (backwards compatibility)', async () => {
+			const hash = await bcrypt.hash('test', salt);
+			const match = await password.compare('test', hash, false);
+			assert(match);
+		});
+
+		it('should continue to function even with passwords > 73 characters', async () => {
+			const arr = [];
+			arr.length = 100;
+			const hash = await password.hash(12, arr.join('a'));
+
+			arr.length = 150;
+			const match = await password.compare(arr.join('a'), hash, true);
+			assert.strictEqual(match, false);
+		});
+
+		it('should process a million-character long password quickly', async () => {
+			// ... because sha512 reduces it to a constant size
+			const arr = [];
+			const start = Date.now();
+			arr.length = 1000000;
+			await password.hash(12, arr.join('a'));
+			const end = Date.now();
+
+			assert(end - start < 5000);
+		});
+	});
+});

test/user.js

@@ -584,7 +584,7 @@ describe('User', function () {
 					},
 				}, function (err, results) {
 					assert.ifError(err);
-					Password.compare('newpassword', results.password, function (err, match) {
+					Password.compare('newpassword', results.password, true, function (err, match) {
 						assert.ifError(err);
 						assert(match);
 						assert.strictEqual(results.userData['email:confirmed'], 1);