noble-ciphers

Auditable & minimal JS implementation of AES SIV, Salsa20 and ChaCha20.

• 🔒 Auditable
• 🔻 Tree-shaking-friendly: use only what's necessary, other code won't be included
• 🏎 Ultra-fast, hand-optimized for caveats of JS engines
• 🔍 Unique tests ensure correctness: property-based, cross-library and Wycheproof vectors
• 💼 AES: GCM (Galois Counter Mode), SIV (Nonce Misuse-Resistant encryption)
• 💃 Salsa20, ChaCha20, XSalsa20, XChaCha20, Poly1305, ChaCha8, ChaCha12
• ✍️ FF1 format-preserving encryption
• 🧂 Compatible with NaCl / libsodium secretbox
• 🪶 Just 500 lines / 4KB gzipped for Salsa + ChaCha + Poly build

_slow file contains minimal, readable implementation of algorithms. Other files contain unrolled loops, which are fast, but less auditable.

This library belongs to noble crypto

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

• No dependencies, protection against supply chain attacks
• Auditable TypeScript / JS code
• Supported on all major platforms
• Releases are signed with PGP keys and built transparently with NPM provenance
• Check out homepage & all libraries: ciphers, curves (4kb versions secp256k1, ed25519), hashes

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 crypto.getRandomValues. If you don't like NPM, a standalone noble-ciphers.js is also available.

// import * from '@noble/ciphers'; // Error
// Use sub-imports for tree-shaking, to ensure small size of your apps
import { xsalsa20_poly1305, secretbox } from '@noble/ciphers/salsa';
import { chacha20_poly1305 } from '@noble/ciphers/chacha';
import { randomBytes } from '@noble/ciphers/webcrypto/utils';
import { utf8ToBytes } from '@noble/ciphers/utils';

const key = randomBytes(32);
const data = utf8ToBytes('hello, noble'); // strings must be converted to Uint8Array

const nonce24 = randomBytes(24);
const stream_s = xsalsa20_poly1305(key, nonce24);
const encrypted_s = stream_s.encrypt(data);
stream_s.decrypt(encrypted_s); // === data

const nonce12 = randomBytes(12);
const stream_c = chacha20_poly1305(key, nonce12);
const encrypted_c = stream_c.encrypt(data);
stream_c.decrypt(encrypted_c); // === data

import {
  aes_128_gcm, aes_128_ctr, aes_128_cbc,
  aes_256_gcm, aes_256_ctr, aes_256_cbc
} from '@noble/ciphers/webcrypto/aes';

const stream_aes = aes_256_gcm(key, nonce);
const ciphertext_aes = await stream_aes.encrypt(data); // async
const plaintext_aes = await stream_a.decrypt(ciphertext_aes); // === data

import { aes_256_gcm_siv } from '@noble/ciphers/webcrypto/siv';
import { FF1, BinaryFF1 } from '@noble/ciphers/webcrypto/ff1';

// All algoritms, written in minimal, auditable way
import * as ciphers from '@noble/ciphers/_slow';

How to encrypt properly

1. Use unpredictable, random key; don't re-use keys between different protocols
2. Use new nonce every time and don't repeat it
3. Be aware of rules for cryptographic key wear-out and encryption limits
4. Prefer authenticated encryption, with MACs like poly1305, GCM, hmac

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.

To safely use random nonces, utilize XSalsa20 or XChaCha20: 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 RFC draft 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

Salsa

import { xsalsa20_poly1305, secretbox } from '@noble/ciphers/salsa';
import { utf8ToBytes } from '@noble/ciphers/utils';
import { randomBytes } from '@noble/ciphers/webcrypto/utils';

const key = randomBytes(32);
const data = utf8ToBytes('hello, noble'); // strings must be converted to Uint8Array

const nonce = randomBytes(24);
const stream_x = xsalsa20_poly1305(key, nonce); // === secretbox(key, nonce)
const ciphertext = stream_x.encrypt(data);      // === secretbox.seal(data)
const plaintext = stream_x.decrypt(ciphertext); // === secretbox.open(ciphertext)

// We provide sodium secretbox alias, which is just xsalsa20_poly1305
const box = secretbox(key, nonce);
const ciphertext = box.seal(plaintext);
const plaintext = box.open(ciphertext);


// Standalone salsa is also available
import { salsa20, xsalsa20 } from '@noble/ciphers/salsa';
const nonce12 = randomBytes(12); // salsa uses 96-bit nonce, xsalsa uses 192-bit
const encrypted_s = salsa20(key, nonce12, data);
const encrypted_xs = xsalsa20(key, nonce, data);

Salsa20 stream cipher (website, PDF, wiki) 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.

ChaCha

import { chacha20_poly1305, xchacha20_poly1305 } from '@noble/ciphers/chacha';
import { utf8ToBytes } from '@noble/ciphers/utils';
import { randomBytes } from '@noble/ciphers/webcrypto/utils';

const key = randomBytes(32);
const data = utf8ToBytes('hello, noble'); // strings must be converted to Uint8Array

const nonce12 = randomBytes(12); // chacha uses 96-bit nonce
const stream_c = chacha20_poly1305(key, nonce12);
const ciphertext_c = stream_c.encrypt(data);
const plaintext_c = stream_c.decrypt(ciphertext_c); // === data

const nonce24 = randomBytes(24); // xchacha uses 192-bit nonce
const stream_xc = xchacha20_poly1305(key, nonce24);
const ciphertext_xc = stream_xc.encrypt(data);
const plaintext_xc = stream_xc.decrypt(ciphertext_xc); // === data


// Standalone chacha is also available
import { chacha20, xchacha20, chacha8, chacha12 } from '@noble/ciphers/chacha';
const ciphertext_pc = chacha20(key, nonce12, data);
const ciphertext_pxc = xchacha20(key, nonce24, data);
const ciphertext_8 = chacha8(key, nonce12, data);
const ciphertext_12 = chacha12(key, nonce12, data);

ChaCha20 stream cipher (website, PDF, wiki, blog post) 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 (draft RFC) extended-nonce variant is also provided. Similar to XSalsa, it's safe to use with randomly-generated nonces.

Poly1305

Poly1305 (website, PDF, wiki, blog post) 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.

Poly1305 is polynomial-evaluation MAC, which is not perfect for every situation: just like GCM, it lacks Random Key Robustness: the tags 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.

Even though poly1305 can be imported separately from the library, we suggest using chacha-poly or xsalsa-poly.

AES

import {
  aes_128_gcm, aes_128_ctr, aes_128_cbc,
  aes_256_gcm, aes_256_ctr, aes_256_cbc
} from '@noble/ciphers/webcrypto/aes';

for (let cipher of [aes_256_gcm, aes_256_ctr, aes_256_cbc]) {
  const stream_new = cipher(key, nonce);
  const ciphertext_new = await stream_new.encrypt(plaintext);
  const plaintext_new = await stream_new.decrypt(ciphertext);
}

import { aes_256_gcm_siv } from '@noble/ciphers/webcrypto/siv';
const stream_siv = aes_256_gcm_siv(key, nonce)
await stream_siv.encrypt(plaintext, AAD);

AES (wiki) is a variant of Rijndael block cipher, standardized by NIST.

We don't implement AES in pure JS for now: instead, we wrap WebCrypto built-in and provide an improved, simple API. There is a simple reason for this: webcrypto API is terrible: different block modes require different params.

Optional AES-GCM-SIV (synthetic initialization vector) nonce-misuse-resistant mode is also provided.

How AES works

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.

Block modes

We only expose GCM & SIV for now.

• ECB — simple deterministic replacement. Dangerous: always map x to y. See AES Penguin
• CBC — key is previous round’s block. Hard to use: need proper padding, also needs MAC
• CTR — counter, allows to create streaming cipher. Requires good IV. Parallelizable. OK, but no MAC
• GCM — modern CTR, parallel, with MAC. Not ideal:
  • Conservative key wear-out is 2**32 (4B) msgs
  • MAC can be forged: see Poly1305 section above
• SIV — synthetic initialization vector, nonce-misuse-resistant
  • Can be 1.5-2x slower than GCM by itself
  • nonce misuse-resistant schemes guarantee that if a nonce repeats, then the only security loss is that identical plaintexts will produce identical ciphertexts
  • MAC can be forged: see Poly1305 section above
• XTS — used in hard drives. Similar to ECB (deterministic), but has [i][j] tweak arguments corresponding to sector i and 16-byte block (part of sector) j. Not authenticated!

FF1

Format-preserving encryption algorithm (FPE-FF1) specified in NIST Special Publication 800-38G.

More info: https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-38G.pdf

Security

The library is experimental. Use at your own risk.

Speed

Benchmark results on Apple M2 with node v20:

encrypt (32B)
├─salsa x 1,562,500 ops/sec @ 640ns/op
├─chacha x 1,968,503 ops/sec @ 508ns/op
├─xsalsa x 969,932 ops/sec @ 1μs/op
├─xchacha x 959,692 ops/sec @ 1μs/op
├─xsalsa20_poly1305 x 554,631 ops/sec @ 1μs/op
├─chacha20_poly1305 x 542,888 ops/sec @ 1μs/op
└─xchacha20poly1305 x 346,140 ops/sec @ 2μs/op

encrypt (64B)
├─salsa x 1,392,757 ops/sec @ 718ns/op
├─chacha x 1,709,401 ops/sec @ 585ns/op
├─xsalsa x 892,857 ops/sec @ 1μs/op
├─xchacha x 888,099 ops/sec @ 1μs/op
├─xsalsa20_poly1305 x 476,871 ops/sec @ 2μs/op
├─chacha20_poly1305 x 488,997 ops/sec @ 2μs/op
└─xchacha20poly1305 x 326,157 ops/sec @ 3μs/op

encrypt (1KB)
├─salsa x 219,780 ops/sec @ 4μs/op
├─chacha x 227,634 ops/sec @ 4μs/op
├─xsalsa x 204,290 ops/sec @ 4μs/op
├─xchacha x 203,873 ops/sec @ 4μs/op
├─xsalsa20_poly1305 x 116,049 ops/sec @ 8μs/op
├─chacha20_poly1305 x 116,522 ops/sec @ 8μs/op
└─xchacha20poly1305 x 103,487 ops/sec @ 9μs/op

encrypt (8KB)
├─salsa x 30,695 ops/sec @ 32μs/op
├─chacha x 30,817 ops/sec @ 32μs/op
├─xsalsa x 30,193 ops/sec @ 33μs/op
├─xchacha x 30,255 ops/sec @ 33μs/op
├─xsalsa20_poly1305 x 17,402 ops/sec @ 57μs/op
├─chacha20_poly1305 x 17,513 ops/sec @ 57μs/op
└─xchacha20poly1305 x 17,208 ops/sec @ 58μs/op

encrypt (1MB)
├─salsa x 249 ops/sec @ 4ms/op
├─chacha x 250 ops/sec @ 3ms/op
├─xsalsa x 249 ops/sec @ 4ms/op
├─xchacha x 250 ops/sec @ 3ms/op
├─xsalsa20_poly1305 x 142 ops/sec @ 7ms/op
├─chacha20_poly1305 x 143 ops/sec @ 6ms/op
└─xchacha20poly1305 x 143 ops/sec @ 6ms/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

License

The MIT License (MIT)

Copyright (c) 2023 Paul Miller (https://paulmillr.com) Copyright (c) 2016 Thomas Pornin pornin@bolet.org

See LICENSE file.