@noble/ciphers

noble-ciphers

Audited & minimal JS implementation of Salsa20, ChaCha and AES.

• 🔒 Audited by an independent security firm
• 🔻 Tree-shakeable: unused code is excluded from your builds
• 🏎 Fast: hand-optimized for caveats of JS engines
• 🔍 Reliable: property-based / cross-library / wycheproof tests ensure correctness
• 💼 AES: ECB, CBC, CTR, CFB, GCM, SIV (nonce misuse-resistant), AESKW, AESKWP
• 💃 Salsa20, ChaCha, XSalsa20, XChaCha, ChaCha8, ChaCha12, Poly1305
• 🥈 Two AES implementations: pure JS or friendly wrapper around webcrypto
• 🪶 29KB (11KB gzipped) for everything, 7KB (3KB gzipped) for ChaCha build

Take a glance at GitHub Discussions for questions and support.

This library belongs to noble cryptography

noble cryptography — high-security, easily auditable set of contained cryptographic libraries and tools.

• Zero or minimal dependencies
• Highly readable TypeScript / JS code
• PGP-signed releases and transparent NPM builds
• All libraries: ciphers, curves, hashes, post-quantum, 4kb secp256k1 / ed25519
• Check out homepage for reading resources, documentation and apps built with noble

Usage

npm install @noble/ciphers

We support all major platforms and runtimes. For Deno, ensure to use npm specifier. For React Native, you may need a polyfill for getRandomValues. A standalone file noble-ciphers.js is also available.

// import * from '@noble/ciphers'; // Error: use sub-imports, to ensure small app size
import { xchacha20poly1305 } from '@noble/ciphers/chacha';
// import { xchacha20poly1305 } from 'npm:@noble/ciphers@1.1.0/chacha'; // Deno

• Examples
  • Encrypt with XChaCha20-Poly1305
  • Encrypt with AES-256-GCM
  • AES: gcm, siv, ctr, cfb, cbc, ecb
  • Friendly WebCrypto AES
  • AESKW and AESKWP
  • Auto-handle nonces
  • Reuse array for input and output
  • All imports
• Internals
  • Implemented primitives
  • Which cipher should I pick?
  • How to encrypt properly
  • Nonces
  • Encryption limits
  • AES internals and block modes
• Security
• Speed
• Upgrading
• Contributing & testing
• Resources

Examples

[!NOTE] Use different nonce every time encrypt() is done.

Encrypt with XChaCha20-Poly1305

import { xchacha20poly1305 } from '@noble/ciphers/chacha';
import { utf8ToBytes } from '@noble/ciphers/utils';
import { randomBytes } from '@noble/ciphers/webcrypto';
const key = randomBytes(32);    // random key
// const key = new Uint8Array([ // existing key
//   169, 88, 160, 139, 168, 29, 147, 196, 14, 88, 237, 76, 243, 177, 109, 140,
//   195, 140, 80, 10, 216, 134, 215, 71, 191, 48, 20, 104, 189, 37, 38, 55,
// ]);
// import { hexToBytes } from '@noble/ciphers/utils'; // hex key
// const key = hexToBytes('4b7f89bac90a1086fef73f5da2cbe93b2fae9dfbf7678ae1f3e75fd118ddf999');
const nonce = randomBytes(24);
const chacha = xchacha20poly1305(key, nonce);
const data = utf8ToBytes('hello, noble');
const ciphertext = chacha.encrypt(data);
const data_ = chacha.decrypt(ciphertext); // utils.bytesToUtf8(data_) === data

Encrypt with AES-256-GCM

import { gcm } from '@noble/ciphers/aes';
import { utf8ToBytes } from '@noble/ciphers/utils';
import { randomBytes } from '@noble/ciphers/webcrypto';
const key = randomBytes(32);
const nonce = randomBytes(24);
const data = utf8ToBytes('hello, noble');
const aes = gcm(key, nonce);
const ciphertext = aes.encrypt(data);
const data_ = aes.decrypt(ciphertext); // utils.bytesToUtf8(data_) === data

AES: gcm, siv, ctr, cfb, cbc, ecb

import { gcm, siv, ctr, cfb, cbc, ecb } from '@noble/ciphers/aes';
import { randomBytes } from '@noble/ciphers/webcrypto';
const plaintext = new Uint8Array(32).fill(16);
for (let cipher of [gcm, siv]) {
  const key = randomBytes(32); // 24 for AES-192, 16 for AES-128
  const nonce = randomBytes(12);
  const ciphertext_ = cipher(key, nonce).encrypt(plaintext);
  const plaintext_ = cipher(key, nonce).decrypt(ciphertext_);
}
for (const cipher of [ctr, cbc, cfb]) {
  const key = randomBytes(32); // 24 for AES-192, 16 for AES-128
  const nonce = randomBytes(16);
  const ciphertext_ = cipher(key, nonce).encrypt(plaintext);
  const plaintext_ = cipher(key, nonce).decrypt(ciphertext_);
}
for (const cipher of [ecb]) {
  const key = randomBytes(32); // 24 for AES-192, 16 for AES-128
  const ciphertext_ = cipher(key).encrypt(plaintext);
  const plaintext_ = cipher(key).decrypt(ciphertext_);
}

Friendly WebCrypto AES

Noble implements AES. Sometimes people want to use built-in crypto.subtle instead. However, it has terrible API. We simplify access to built-ins.

[!NOTE] Webcrypto methods are always async.

import { gcm, ctr, cbc, randomBytes } from '@noble/ciphers/webcrypto';
const plaintext = new Uint8Array(32).fill(16);
const key = randomBytes(32);
for (const cipher of [gcm]) {
  const nonce = randomBytes(12);
  const ciphertext_ = await cipher(key, nonce).encrypt(plaintext);
  const plaintext_ = await cipher(key, nonce).decrypt(ciphertext_);
}
for (const cipher of [ctr, cbc]) {
  const nonce = randomBytes(16);
  const ciphertext_ = await cipher(key, nonce).encrypt(plaintext);
  const plaintext_ = await cipher(key, nonce).decrypt(ciphertext_);
}

AESKW and AESKWP

import { aeskw, aeskwp } from '@noble/ciphers/aes';
import { hexToBytes } from '@noble/ciphers/utils';

const kek = hexToBytes('000102030405060708090A0B0C0D0E0F');
const keyData = hexToBytes('00112233445566778899AABBCCDDEEFF');
const ciphertext =  aeskw(kek).encrypt(keyData);

Auto-handle nonces

We provide API that manages nonce internally instead of exposing them to library's user.

For encrypt, a nonceBytes-length buffer is fetched from CSPRNG and prenended to encrypted ciphertext.

For decrypt, first nonceBytes of ciphertext are treated as nonce.

import { xchacha20poly1305 } from '@noble/ciphers/chacha';
import { managedNonce } from '@noble/ciphers/webcrypto';
import { hexToBytes, utf8ToBytes } from '@noble/ciphers/utils';
const key = hexToBytes('fa686bfdffd3758f6377abbc23bf3d9bdc1a0dda4a6e7f8dbdd579fa1ff6d7e1');
const chacha = managedNonce(xchacha20poly1305)(key); // manages nonces for you
const data = utf8ToBytes('hello, noble');
const ciphertext = chacha.encrypt(data);
const data_ = chacha.decrypt(ciphertext);

Reuse array for input and output

To avoid additional allocations, Uint8Array can be reused between encryption and decryption calls.

[!NOTE] Some ciphers don't support unaligned (byteOffset % 4 !== 0) Uint8Array as destination. It can decrease performance, making the optimization pointless.

import { chacha20poly1305 } from '@noble/ciphers/chacha';
import { utf8ToBytes } from '@noble/ciphers/utils';
import { randomBytes } from '@noble/ciphers/webcrypto';

const key = randomBytes(32);
const nonce = randomBytes(12);
const chacha = chacha20poly1305(key, nonce);

const input = utf8ToBytes('hello, noble'); // length == 12
const inputLength = input.length;
const tagLength = 16;

const buf = new Uint8Array(inputLength + tagLength);
const start = buf.subarray(0, inputLength);
start.set(input); // copy input to buf

chacha.encrypt(start, buf); // encrypt into `buf`
chacha.decrypt(buf, start); // decrypt into `start`

xsalsa20poly1305 also supports this, but requires 32 additional bytes for encryption / decryption, due to its inner workings.

All imports

import { gcm, siv } from '@noble/ciphers/aes';
import { xsalsa20poly1305 } from '@noble/ciphers/salsa';
import { secretbox } from '@noble/ciphers/salsa'; // == xsalsa20poly1305
import { chacha20poly1305, xchacha20poly1305 } from '@noble/ciphers/chacha';

// Unauthenticated encryption: make sure to use HMAC or similar
import { ctr, cfb, cbc, ecb } from '@noble/ciphers/aes';
import { salsa20, xsalsa20 } from '@noble/ciphers/salsa';
import { chacha20, xchacha20, chacha8, chacha12 } from '@noble/ciphers/chacha';

// KW
import { aeskw, aeskwp } from '@noble/ciphers/aes';

// Utilities
import { bytesToHex, hexToBytes, bytesToUtf8, utf8ToBytes } from '@noble/ciphers/utils';
import { managedNonce, randomBytes } from '@noble/ciphers/webcrypto';
import { poly1305 } from '@noble/ciphers/_poly1305';
import { ghash, polyval } from '@noble/ciphers/_polyval';

Internals

Implemented primitives

• Salsa20 stream cipher was released in 2005. Salsa's goal was to implement AES replacement that does not rely on S-Boxes, which are hard to implement in a constant-time manner. Salsa20 is usually faster than AES, a big deal on slow, budget mobile phones.
  • XSalsa20, extended-nonce variant was released in 2008. It switched nonces from 96-bit to 192-bit, and became safe to be picked at random.
  • Nacl / Libsodium popularized term "secretbox", a simple black-box authenticated encryption. Secretbox is just xsalsa20-poly1305. We provide the alias and corresponding seal / open methods. We don't provide "box" or "sealedbox".
  • Check out PDF and wiki.
• ChaCha20 stream cipher was released in 2008. ChaCha aims to increase the diffusion per round, but had slightly less cryptanalysis. It was standardized in RFC 8439 and is now used in TLS 1.3.
  • XChaCha20 extended-nonce variant is also provided. Similar to XSalsa, it's safe to use with randomly-generated nonces.
  • Check out PDF and wiki.
• AES is a variant of Rijndael block cipher, standardized by NIST in 2001. We provide the fastest available pure JS implementation.
  • We support AES-128, AES-192 and AES-256: the mode is selected dynamically, based on key length (16, 24, 32).
  • AES-GCM-SIV nonce-misuse-resistant mode is also provided. It's recommended to use it, to prevent catastrophic consequences of nonce reuse. Our implementation of SIV has the same speed as GCM: there is no performance hit.
  • We also have AESKW and AESKWP from RFC 3394 / RFC 5649
  • Check out AES internals and block modes.
• We expose polynomial-evaluation MACs: Poly1305, AES-GCM's GHash and AES-SIV's Polyval.
  • Poly1305 (PDF, wiki) is a fast and parallel secret-key message-authentication code suitable for a wide variety of applications. It was standardized in RFC 8439 and is now used in TLS 1.3.
  • Polynomial MACs are not perfect for every situation: they lack Random Key Robustness: the MAC can be forged, and can't be used in PAKE schemes. See invisible salamanders attack. To combat invisible salamanders, hash(key) can be included in ciphertext, however, this would violate ciphertext indistinguishability: an attacker would know which key was used - so HKDF(key, i) could be used instead.
• Format-preserving encryption algorithm (FPE-FF1) specified in NIST Special Publication 800-38G. See more info.

Which cipher should I pick?

We suggest to use XChaCha20-Poly1305. If you can't use it, prefer AES-GCM-SIV, or AES-GCM.

How to encrypt properly

• Use unpredictable key with enough entropy
  • Random key must be using cryptographically secure random number generator (CSPRNG), not Math.random etc.
  • Non-random key generated from KDF is fine
  • Re-using key is fine, but be aware of rules for cryptographic key wear-out and encryption limits
• Use new nonce every time and don't repeat it
  • chacha and salsa20 are fine for sequential counters that never repeat: 01, 02...
  • xchacha and xsalsa20 should be used for random nonces instead
  • AES-GCM should use 12-byte nonces: smaller nonces are security risk
• Prefer authenticated encryption (AEAD)
  • chacha20poly1305 / aes-gcm / ChaCha + HMAC / AES + HMAC is good
  • chacha20 / aes-ctr / aes-cbc without poly1305 or hmac is bad
  • Flipping bits or ciphertext substitution won't be detected in unauthenticated ciphers
• Don't re-use keys between different protocols
  • For example, using secp256k1 key in AES can be bad
  • Use hkdf or, at least, a hash function to create sub-key instead

Nonces

Most ciphers need a key and a nonce (aka initialization vector / IV) to encrypt a data:

ciphertext = encrypt(plaintext, key, nonce)

Repeating (key, nonce) pair with different plaintexts would allow an attacker to decrypt it:

ciphertext_a = encrypt(plaintext_a, key, nonce)
ciphertext_b = encrypt(plaintext_b, key, nonce)
stream_diff = xor(ciphertext_a, ciphertext_b)   # Break encryption

So, you can't repeat nonces. One way of doing so is using counters:

for i in 0..:
    ciphertext[i] = encrypt(plaintexts[i], key, i)

Another is generating random nonce every time:

for i in 0..:
    rand_nonces[i] = random()
    ciphertext[i] = encrypt(plaintexts[i], key, rand_nonces[i])

Counters are OK, but it's not always possible to store current counter value: e.g. in decentralized, unsyncable systems.

Randomness is OK, but there's a catch: ChaCha20 and AES-GCM use 96-bit / 12-byte nonces, which implies higher chance of collision. In the example above, random() can collide and produce repeating nonce. Chance is even higher for 64-bit nonces, which GCM allows - don't use them.

To safely use random nonces, utilize XSalsa20 or XChaCha: they increased nonce length to 192-bit, minimizing a chance of collision. AES-SIV is also fine. In situations where you can't use eXtended-nonce algorithms, key rotation is advised. hkdf would work great for this case.

Encryption limits

A "protected message" would mean a probability of 2**-50 that a passive attacker successfully distinguishes the ciphertext outputs of the AEAD scheme from the outputs of a random function. See draft-irtf-cfrg-aead-limits for details.

• Max message size:
  • AES-GCM: ~68GB, 2**36-256
  • Salsa, ChaCha, XSalsa, XChaCha: ~256GB, 2**38-64
• Max amount of protected messages, under same key:
  • AES-GCM: 2**32.5
  • Salsa, ChaCha: 2**46, but only integrity is affected, not confidentiality
  • XSalsa, XChaCha: 2**72
• Max amount of protected messages, across all keys:
  • AES-GCM: 2**69/B where B is max blocks encrypted by a key. Meaning 2**59 for 1KB, 2**49 for 1MB, 2**39 for 1GB
  • Salsa, ChaCha, XSalsa, XChaCha: 2**100

AES internals and block modes

cipher = encrypt(block, key). Data is split into 128-bit blocks. Encrypted in 10/12/14 rounds (128/192/256bit). Every round does:

1. S-box, table substitution
2. Shift rows, cyclic shift left of all rows of data array
3. Mix columns, multiplying every column by fixed polynomial
4. Add round key, round_key xor i-th column of array

For non-deterministic (not ECB) schemes, initialization vector (IV) is mixed to block/key; and each new round either depends on previous block's key, or on some counter.

• ECB (Electronic Codebook): Deterministic encryption; identical plaintext blocks yield identical ciphertexts. Insecure due to pattern leakage. See AES Penguin
• CBC (Cipher Block Chaining): Each plaintext block is XORed with the previous ciphertext block before encryption. Hard to use: requires proper padding and an IV. Needs a separate MAC.
• CTR (Counter Mode): Turns a block cipher into a stream cipher using a counter and IV (nonce). Efficient and parallelizable. Requires a unique nonce per encryption. Better, but still needs a separate MAC.
• GCM (Galois/Counter Mode): Combines CTR mode with polynomial MAC. Efficient and widely used.
• SIV (Synthetic IV): Nonce-misuse-resistant mode; repeating nonces reveal only if plaintexts are identical. Maintains security even if nonces are reused.
• XTS: Designed for disk encryption. Similar to ECB (deterministic), but has [i][j] tweak arguments corresponding to sector i and 16-byte block (part of sector) j. Lacks MAC.

GCM / SIV are not ideal:

• Conservative key wear-out is 2**32 (4B) msgs
• MAC can be forged: see Poly1305 section above. Same for SIV

Security

The library has been independently audited:

• at version 1.0.0, in Sep 2024, by cure53
  • PDFs: website, in-repo
  • Changes since audit
  • Scope: everything
  • The audit has been funded by OpenSats

It is tested against property-based, cross-library and Wycheproof vectors, and has fuzzing by Guido Vranken's cryptofuzz.

If you see anything unusual: investigate and report.

Constant-timeness

JIT-compiler and Garbage Collector make "constant time" extremely hard to achieve timing attack resistance in a scripting language. Which means any other JS library can't have constant-timeness. Even statically typed Rust, a language without GC, makes it harder to achieve constant-time for some cases. If your goal is absolute security, don't use any JS lib — including bindings to native ones. Use low-level libraries & languages. Nonetheless we're targetting algorithmic constant time.

The library uses T-tables for AES, which leak access timings. This is also done in OpenSSL and Go stdlib for performance reasons.

Supply chain security

• Commits are signed with PGP keys, to prevent forgery. Make sure to verify commit signatures.
• Releases are transparent and built on GitHub CI. Make sure to verify provenance logs
• Rare releasing is followed to ensure less re-audit need for end-users
• Dependencies are minimized and locked-down:
  • If your app has 500 dependencies, any dep could get hacked and you'll be downloading malware with every install. We make sure to use as few dependencies as possible
  • We prevent automatic dependency updates by locking-down version ranges. Every update is checked with npm-diff
• Dev Dependencies are only used if you want to contribute to the repo. They are disabled for end-users:
  • scure-base, micro-bmark and micro-should are developed by the same author and follow identical security practices
  • prettier (linter), fast-check (property-based testing) and typescript are used for code quality, vector generation and ts compilation. The packages are big, which makes it hard to audit their source code thoroughly and fully

Randomness

We're deferring to built-in crypto.getRandomValues which is considered cryptographically secure (CSPRNG).

In the past, browsers had bugs that made it weak: it may happen again. Implementing a userspace CSPRNG to get resilient to the weakness is even worse: there is no reliable userspace source of quality entropy.

Speed

To summarize, noble is the fastest JS implementation of Salsa, ChaCha and AES.

You can gain additional speed-up and avoid memory allocations by passing output uint8array into encrypt / decrypt methods.

Benchmark results on Apple M2 with node v22:

encrypt (64B)
├─xsalsa20poly1305 x 485,908 ops/sec @ 2μs/op
├─chacha20poly1305 x 414,250 ops/sec @ 2μs/op
├─xchacha20poly1305 x 331,674 ops/sec @ 3μs/op
├─aes-256-gcm x 144,237 ops/sec @ 6μs/op
└─aes-256-gcm-siv x 121,373 ops/sec @ 8μs/op
encrypt (1KB)
├─xsalsa20poly1305 x 136,574 ops/sec @ 7μs/op
├─chacha20poly1305 x 136,017 ops/sec @ 7μs/op
├─xchacha20poly1305 x 126,008 ops/sec @ 7μs/op
├─aes-256-gcm x 40,149 ops/sec @ 24μs/op
└─aes-256-gcm-siv x 37,420 ops/sec @ 26μs/op
encrypt (8KB)
├─xsalsa20poly1305 x 22,517 ops/sec @ 44μs/op
├─chacha20poly1305 x 23,187 ops/sec @ 43μs/op
├─xchacha20poly1305 x 22,837 ops/sec @ 43μs/op
├─aes-256-gcm x 7,993 ops/sec @ 125μs/op
└─aes-256-gcm-siv x 7,836 ops/sec @ 127μs/op
encrypt (1MB)
├─xsalsa20poly1305 x 186 ops/sec @ 5ms/op
├─chacha20poly1305 x 191 ops/sec @ 5ms/op
├─xchacha20poly1305 x 191 ops/sec @ 5ms/op
├─aes-256-gcm x 71 ops/sec @ 14ms/op
└─aes-256-gcm-siv x 75 ops/sec @ 13ms/op

Unauthenticated encryption:

encrypt (64B)
├─salsa x 1,221,001 ops/sec @ 819ns/op
├─chacha x 1,373,626 ops/sec @ 728ns/op
├─xsalsa x 1,019,367 ops/sec @ 981ns/op
└─xchacha x 1,019,367 ops/sec @ 981ns/op
encrypt (1KB)
├─salsa x 349,162 ops/sec @ 2μs/op
├─chacha x 372,717 ops/sec @ 2μs/op
├─xsalsa x 327,868 ops/sec @ 3μs/op
└─xchacha x 332,446 ops/sec @ 3μs/op
encrypt (8KB)
├─salsa x 55,178 ops/sec @ 18μs/op
├─chacha x 51,535 ops/sec @ 19μs/op
├─xsalsa x 54,274 ops/sec @ 18μs/op
└─xchacha x 55,645 ops/sec @ 17μs/op
encrypt (1MB)
├─salsa x 451 ops/sec @ 2ms/op
├─chacha x 464 ops/sec @ 2ms/op
├─xsalsa x 455 ops/sec @ 2ms/op
└─xchacha x 462 ops/sec @ 2ms/op

AES
encrypt (64B)
├─ctr-256 x 679,347 ops/sec @ 1μs/op
├─cbc-256 x 699,300 ops/sec @ 1μs/op
└─ecb-256 x 717,875 ops/sec @ 1μs/op
encrypt (1KB)
├─ctr-256 x 93,423 ops/sec @ 10μs/op
├─cbc-256 x 95,721 ops/sec @ 10μs/op
└─ecb-256 x 154,726 ops/sec @ 6μs/op
encrypt (8KB)
├─ctr-256 x 12,908 ops/sec @ 77μs/op
├─cbc-256 x 13,411 ops/sec @ 74μs/op
└─ecb-256 x 22,681 ops/sec @ 44μs/op
encrypt (1MB)
├─ctr-256 x 105 ops/sec @ 9ms/op
├─cbc-256 x 108 ops/sec @ 9ms/op
└─ecb-256 x 181 ops/sec @ 5ms/op

Compare to other implementations:

xsalsa20poly1305 (encrypt, 1MB)
├─tweetnacl x 108 ops/sec @ 9ms/op
└─noble x 190 ops/sec @ 5ms/op

chacha20poly1305 (encrypt, 1MB)
├─node x 1,360 ops/sec @ 735μs/op
├─stablelib x 117 ops/sec @ 8ms/op
└─noble x 193 ops/sec @ 5ms/op

chacha (encrypt, 1MB)
├─node x 2,035 ops/sec @ 491μs/op
├─stablelib x 206 ops/sec @ 4ms/op
└─noble x 474 ops/sec @ 2ms/op

ctr-256 (encrypt, 1MB)
├─node x 3,530 ops/sec @ 283μs/op
├─stablelib x 70 ops/sec @ 14ms/op
├─aesjs x 31 ops/sec @ 32ms/op
├─noble-webcrypto x 4,589 ops/sec @ 217μs/op
└─noble x 107 ops/sec @ 9ms/op

cbc-256 (encrypt, 1MB)
├─node x 993 ops/sec @ 1ms/op
├─stablelib x 63 ops/sec @ 15ms/op
├─aesjs x 29 ops/sec @ 34ms/op
├─noble-webcrypto x 1,087 ops/sec @ 919μs/op
└─noble x 110 ops/sec @ 9ms/op

gcm-256 (encrypt, 1MB)
├─node x 3,196 ops/sec @ 312μs/op
├─stablelib x 27 ops/sec @ 36ms/op
├─noble-webcrypto x 4,059 ops/sec @ 246μs/op
└─noble x 74 ops/sec @ 13ms/op

Contributing & testing

1. Clone the repository
2. npm install to install build dependencies like TypeScript
3. npm run build to compile TypeScript code
4. npm run test will execute all main tests

Resources

Check out paulmillr.com/noble for useful resources, articles, documentation and demos related to the library.

License

The MIT License (MIT)

Copyright (c) 2023 Paul Miller (https://paulmillr.com) Copyright (c) 2016 Thomas Pornin [e-mail]

See LICENSE file.