@noble/post-quantum
Version:
Auditable & minimal JS implementation of post-quantum cryptography: FIPS 203, 204, 205, Falcon
391 lines • 15.3 kB
JavaScript
/**
* Utilities for hex, bytearray and number handling.
* @module
*/
/*! noble-post-quantum - MIT License (c) 2024 Paul Miller (paulmillr.com) */
import { abytes, abytes as abytes_, concatBytes, isLE, randomBytes as randb, } from '@noble/hashes/utils.js';
/**
* Asserts that a value is a byte array and optionally checks its length.
* Returns the original reference unchanged on success, and currently also accepts Node `Buffer`
* values through the upstream validator.
* This helper throws on malformed input, so APIs that must return `false` need to guard lengths
* before decoding or before calling it.
* @example
* Validate that a value is a byte array with the expected length.
* ```ts
* abytes(new Uint8Array([1]), 1);
* ```
*/
const abytesDoc = abytes;
export { abytesDoc as abytes };
/**
* Concatenates byte arrays into a new `Uint8Array`.
* Zero arguments return an empty `Uint8Array`.
* Invalid segments throw before allocation because each argument is validated first.
* @example
* Concatenate two byte arrays into one result.
* ```ts
* concatBytes(new Uint8Array([1]), new Uint8Array([2]));
* ```
*/
const concatBytesDoc = concatBytes;
export { concatBytesDoc as concatBytes };
/**
* Returns cryptographically secure random bytes.
* Requires `globalThis.crypto.getRandomValues` and throws if that API is unavailable.
* `bytesLength` is validated by the upstream helper as a non-negative integer before allocation,
* so negative and fractional values both throw instead of truncating through JS `ToIndex`.
* @param bytesLength - Number of random bytes to generate.
* @returns Fresh random bytes.
* @example
* Generate a fresh random seed.
* ```ts
* const seed = randomBytes(4);
* ```
*/
export const randomBytes = randb;
/**
* Compares two byte arrays in a length-constant way for equal lengths.
* Unequal lengths return `false` immediately, and there is no runtime type validation.
* @param a - First byte array.
* @param b - Second byte array.
* @returns Whether both arrays contain the same bytes.
* @example
* Compare two byte arrays for equality.
* ```ts
* equalBytes(new Uint8Array([1]), new Uint8Array([1]));
* ```
*/
export function equalBytes(a, b) {
if (a.length !== b.length)
return false;
let diff = 0;
for (let i = 0; i < a.length; i++)
diff |= a[i] ^ b[i];
return diff === 0;
}
/**
* Copies bytes into a fresh `Uint8Array`.
* Returns a detached plain `Uint8Array` after validating that the input is real bytes.
* @param bytes - Source bytes.
* @returns Copy of the input bytes.
* @example
* Copy bytes into a fresh array.
* ```ts
* copyBytes(new Uint8Array([1, 2]));
* ```
*/
export function copyBytes(bytes) {
// `Uint8Array.from(...)` would also accept arrays / other typed arrays. Keep this helper strict
// because callers use it at byte-validation boundaries before mutating the detached copy.
return Uint8Array.from(abytes(bytes));
}
/**
* Byte-swaps each 64-bit lane in place.
* Falcon's exact binary64 tables are stored as little-endian byte payloads, so BE runtimes need
* this boundary helper before aliasing them as host `Float64Array` lanes.
* @param arr - Byte buffer whose length is a multiple of 8.
* @returns The same buffer after in-place 64-bit lane byte swaps.
* @example
* Byte-swap one 64-bit lane in place.
* ```ts
* byteSwap64(new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8]));
* ```
*/
export function byteSwap64(arr) {
const bytes = new Uint8Array(arr.buffer, arr.byteOffset, arr.byteLength);
for (let i = 0; i < bytes.length; i += 8) {
const a0 = bytes[i + 0];
const a1 = bytes[i + 1];
const a2 = bytes[i + 2];
const a3 = bytes[i + 3];
bytes[i + 0] = bytes[i + 7];
bytes[i + 1] = bytes[i + 6];
bytes[i + 2] = bytes[i + 5];
bytes[i + 3] = bytes[i + 4];
bytes[i + 4] = a3;
bytes[i + 5] = a2;
bytes[i + 6] = a1;
bytes[i + 7] = a0;
}
return arr;
}
/**
* Byte-swaps 64-bit lanes on big-endian runtimes and returns the input unchanged on little-endian.
* This keeps Falcon's binary64 tables in canonical little-endian order before aliasing them as
* `Float64Array` lanes on the current host.
* @param arr - Buffer to pass through or swap in place.
* @returns The same buffer, normalized for Falcon's little-endian table layout.
* @example
* Normalize one host-endian buffer for Falcon's float tables.
* ```ts
* baswap64If(new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8]));
* ```
*/
export const baswap64If = isLE
? (arr) => arr
: byteSwap64;
/**
* Validates that an options bag is a plain object.
* @param opts - Options object to validate.
* @throws On wrong argument types. {@link TypeError}
* @example
* Validate that an options bag is a plain object.
* ```ts
* validateOpts({});
* ```
*/
export function validateOpts(opts) {
// Arrays silently passed here before, but these call sites expect named option-bag fields.
if (Object.prototype.toString.call(opts) !== '[object Object]')
throw new TypeError('expected valid options object');
}
/**
* Validates common verification options.
* `context` itself is validated with `abytes(...)`, and individual algorithms may narrow support
* further after this shared plain-object gate.
* @param opts - Verification options. See {@link VerOpts}.
* @throws On wrong argument types. {@link TypeError}
* @example
* Validate common verification options.
* ```ts
* validateVerOpts({ context: new Uint8Array([1]) });
* ```
*/
export function validateVerOpts(opts) {
validateOpts(opts);
if (opts.context !== undefined)
abytes(opts.context, undefined, 'opts.context');
}
/**
* Validates common signing options.
* `extraEntropy` is validated with `abytes(...)`; exact lengths and extra algorithm-specific
* restrictions are enforced later by callers.
* @param opts - Signing options. See {@link SigOpts}.
* @throws On wrong argument types. {@link TypeError}
* @example
* Validate common signing options.
* ```ts
* validateSigOpts({ extraEntropy: new Uint8Array([1]) });
* ```
*/
export function validateSigOpts(opts) {
validateVerOpts(opts);
if (opts.extraEntropy !== false && opts.extraEntropy !== undefined)
abytes(opts.extraEntropy, undefined, 'opts.extraEntropy');
}
/**
* Builds a fixed-layout coder from byte lengths and nested coders.
* Raw-length fields decode as zero-copy `subarray(...)` views, and nested coders may preserve that
* aliasing too. Nested coder `encode(...)` results are treated as owned scratch: `splitCoder`
* copies them into the output and then zeroizes them with `fill(0)`. If a nested encoder forwards
* caller-owned bytes, it must do so only after detaching them into a disposable copy.
* @param label - Label used in validation errors.
* @param lengths - Field lengths or nested coders.
* @returns Composite fixed-length coder.
* @example
* Build a fixed-layout coder from byte lengths and nested coders.
* ```ts
* splitCoder('demo', 1, 2).encode([new Uint8Array([1]), new Uint8Array([2, 3])]);
* ```
*/
export function splitCoder(label, ...lengths) {
const getLength = (c) => typeof c === 'number' ? c : c.bytesLen;
const bytesLen = lengths.reduce((sum, a) => sum + getLength(a), 0);
return {
bytesLen,
encode: (bufs) => {
const res = new Uint8Array(bytesLen);
for (let i = 0, pos = 0; i < lengths.length; i++) {
const c = lengths[i];
const l = getLength(c);
const b = typeof c === 'number' ? bufs[i] : c.encode(bufs[i]);
abytes_(b, l, label);
res.set(b, pos);
if (typeof c !== 'number')
b.fill(0); // clean
pos += l;
}
return res;
},
decode: (buf) => {
abytes_(buf, bytesLen, label);
const res = [];
for (const c of lengths) {
const l = getLength(c);
const b = buf.subarray(0, l);
res.push(typeof c === 'number' ? b : c.decode(b));
buf = buf.subarray(l);
}
return res;
},
};
}
// nano-packed.array (fixed size)
/**
* Builds a fixed-length vector coder from another fixed-length coder.
* Element decoding receives `subarray(...)` views, so aliasing depends on the element coder.
* Element coder `encode(...)` results are treated as owned scratch: `vecCoder` copies them into
* the output and then zeroizes them with `fill(0)`. If an element encoder forwards caller-owned
* bytes, it must do so only after detaching them into a disposable copy. `vecCoder` also trusts
* the `BytesCoderLen` contract: each encoded element must already be exactly `c.bytesLen` bytes.
* @param c - Element coder.
* @param vecLen - Number of elements in the vector.
* @returns Fixed-length vector coder.
* @example
* Build a fixed-length vector coder from another fixed-length coder.
* ```ts
* vecCoder(
* { bytesLen: 1, encode: (n: number) => Uint8Array.of(n), decode: (b: Uint8Array) => b[0] || 0 },
* 2
* ).encode([1, 2]);
* ```
*/
export function vecCoder(c, vecLen) {
const coder = c;
const bytesLen = vecLen * coder.bytesLen;
return {
bytesLen,
encode: (u) => {
if (u.length !== vecLen)
throw new RangeError(`vecCoder.encode: wrong length=${u.length}. Expected: ${vecLen}`);
const res = new Uint8Array(bytesLen);
for (let i = 0, pos = 0; i < u.length; i++) {
const b = coder.encode(u[i]);
res.set(b, pos);
b.fill(0); // clean
pos += b.length;
}
return res;
},
decode: (a) => {
abytes_(a, bytesLen);
const r = [];
for (let i = 0; i < a.length; i += coder.bytesLen)
r.push(coder.decode(a.subarray(i, i + coder.bytesLen)));
return r;
},
};
}
/**
* Overwrites supported typed-array inputs with zeroes in place.
* Accepts direct typed arrays and one-level arrays of them.
* @param list - Typed arrays or one-level lists of typed arrays to clear.
* @example
* Overwrite typed arrays with zeroes.
* ```ts
* const buf = Uint8Array.of(1, 2, 3);
* cleanBytes(buf);
* ```
*/
export function cleanBytes(...list) {
for (const t of list) {
if (Array.isArray(t))
for (const b of t)
b.fill(0);
else
t.fill(0);
}
}
/**
* Creates a 32-bit mask with the lowest `bits` bits set.
* @param bits - Number of low bits to keep.
* @returns Bit mask with `bits` ones.
* @throws On wrong argument ranges or values. {@link RangeError}
* @example
* Create a low-bit mask for packed-field operations.
* ```ts
* const mask = getMask(4);
* ```
*/
export function getMask(bits) {
if (!Number.isSafeInteger(bits) || bits < 0 || bits > 32)
throw new RangeError(`expected bits in [0..32], got ${bits}`);
// JS shifts are modulo 32, so bit 32 needs an explicit full-width mask.
return bits === 32 ? 0xffffffff : ~(-1 << bits) >>> 0;
}
/** Shared empty byte array used as the default context. */
export const EMPTY = /* @__PURE__ */ Uint8Array.of();
/**
* Builds the domain-separated message payload for the pure sign/verify paths.
* Context length `255` is valid; only `ctx.length > 255` is rejected.
* @param msg - Message bytes.
* @param ctx - Optional context bytes.
* @returns Domain-separated message payload.
* @throws On wrong argument ranges or values. {@link RangeError}
* @example
* Build the domain-separated payload before direct signing.
* ```ts
* const payload = getMessage(new Uint8Array([1, 2]));
* ```
*/
export function getMessage(msg, ctx = EMPTY) {
abytes_(msg);
abytes_(ctx);
if (ctx.length > 255)
throw new RangeError('context should be 255 bytes or less');
return concatBytes(new Uint8Array([0, ctx.length]), ctx, msg);
}
// DER tag+length plus the shared NIST hash OID arc 2.16.840.1.101.3.4.2.* used by the
// FIPS 204 / FIPS 205 pre-hash wrappers; the final byte selects SHA-256, SHA-512, SHAKE128,
// SHAKE256, or another approved hash/XOF under that subtree.
// 06 09 60 86 48 01 65 03 04 02
const oidNistP = /* @__PURE__ */ Uint8Array.from([6, 9, 0x60, 0x86, 0x48, 1, 0x65, 3, 4, 2]);
/**
* Validates that a hash exposes a NIST hash OID and enough collision resistance.
* Current accepted surface is broader than the FIPS algorithm tables: any hash/XOF under the NIST
* `2.16.840.1.101.3.4.2.*` subtree is accepted if its effective `outputLen` is strong enough.
* XOF callers must pass a callable whose `outputLen` matches the digest length they actually intend
* to sign; bare `shake128` / `shake256` defaults are too short for the stronger prehash modes.
* @param hash - Hash function to validate.
* @param requiredStrength - Minimum required collision-resistance strength in bits.
* @throws If the hash metadata or collision resistance is insufficient. {@link Error}
* @example
* Validate that a hash exposes a NIST hash OID and enough collision resistance.
* ```ts
* import { sha256 } from '@noble/hashes/sha2.js';
* import { checkHash } from '@noble/post-quantum/utils.js';
* checkHash(sha256, 128);
* ```
*/
export function checkHash(hash, requiredStrength = 0) {
if (!hash.oid || !equalBytes(hash.oid.subarray(0, 10), oidNistP))
throw new Error('hash.oid is invalid: expected NIST hash');
// FIPS 204 / FIPS 205 require both collision and second-preimage strength; for approved NIST
// hashes/XOFs under this OID subtree, the collision bound from the configured digest length is
// the tighter runtime check, so enforce that lower bound here.
const collisionResistance = (hash.outputLen * 8) / 2;
if (requiredStrength > collisionResistance) {
throw new Error('Pre-hash security strength too low: ' +
collisionResistance +
', required: ' +
requiredStrength);
}
}
/**
* Builds the domain-separated prehash payload for the prehash sign/verify paths.
* Callers are expected to vet `hash.oid` first, e.g. via `checkHash(...)`; calling this helper
* directly with a hash object that lacks `oid` currently throws later inside `concatBytes(...)`.
* Context length `255` is valid; only `ctx.length > 255` is rejected.
* @param hash - Prehash function.
* @param msg - Message bytes.
* @param ctx - Optional context bytes.
* @returns Domain-separated prehash payload.
* @throws On wrong argument ranges or values. {@link RangeError}
* @example
* Build the domain-separated prehash payload for external hashing.
* ```ts
* import { sha256 } from '@noble/hashes/sha2.js';
* import { getMessagePrehash } from '@noble/post-quantum/utils.js';
* getMessagePrehash(sha256, new Uint8Array([1, 2]));
* ```
*/
export function getMessagePrehash(hash, msg, ctx = EMPTY) {
abytes_(msg);
abytes_(ctx);
if (ctx.length > 255)
throw new RangeError('context should be 255 bytes or less');
const hashed = hash(msg);
return concatBytes(new Uint8Array([1, ctx.length]), ctx, hash.oid, hashed);
}
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