@noble/curves
Version:
Audited & minimal JS implementation of elliptic curve cryptography
335 lines • 12.1 kB
JavaScript
/**
* Hex, bytes and number utilities.
* @module
*/
/*! noble-curves - MIT License (c) 2022 Paul Miller (paulmillr.com) */
// 100 lines of code in the file are duplicated from noble-hashes (utils).
// This is OK: `abstract` directory does not use noble-hashes.
// User may opt-in into using different hashing library. This way, noble-hashes
// won't be included into their bundle.
const _0n = /* @__PURE__ */ BigInt(0);
const _1n = /* @__PURE__ */ BigInt(1);
const _2n = /* @__PURE__ */ BigInt(2);
export function isBytes(a) {
return a instanceof Uint8Array || (ArrayBuffer.isView(a) && a.constructor.name === 'Uint8Array');
}
export function abytes(item) {
if (!isBytes(item))
throw new Error('Uint8Array expected');
}
export function abool(title, value) {
if (typeof value !== 'boolean')
throw new Error(title + ' boolean expected, got ' + value);
}
// Array where index 0xf0 (240) is mapped to string 'f0'
const hexes = /* @__PURE__ */ Array.from({ length: 256 }, (_, i) => i.toString(16).padStart(2, '0'));
/**
* @example bytesToHex(Uint8Array.from([0xca, 0xfe, 0x01, 0x23])) // 'cafe0123'
*/
export function bytesToHex(bytes) {
abytes(bytes);
// pre-caching improves the speed 6x
let hex = '';
for (let i = 0; i < bytes.length; i++) {
hex += hexes[bytes[i]];
}
return hex;
}
export function numberToHexUnpadded(num) {
const hex = num.toString(16);
return hex.length & 1 ? '0' + hex : hex;
}
export function hexToNumber(hex) {
if (typeof hex !== 'string')
throw new Error('hex string expected, got ' + typeof hex);
return hex === '' ? _0n : BigInt('0x' + hex); // Big Endian
}
// We use optimized technique to convert hex string to byte array
const asciis = { _0: 48, _9: 57, A: 65, F: 70, a: 97, f: 102 };
function asciiToBase16(ch) {
if (ch >= asciis._0 && ch <= asciis._9)
return ch - asciis._0; // '2' => 50-48
if (ch >= asciis.A && ch <= asciis.F)
return ch - (asciis.A - 10); // 'B' => 66-(65-10)
if (ch >= asciis.a && ch <= asciis.f)
return ch - (asciis.a - 10); // 'b' => 98-(97-10)
return;
}
/**
* @example hexToBytes('cafe0123') // Uint8Array.from([0xca, 0xfe, 0x01, 0x23])
*/
export function hexToBytes(hex) {
if (typeof hex !== 'string')
throw new Error('hex string expected, got ' + typeof hex);
const hl = hex.length;
const al = hl / 2;
if (hl % 2)
throw new Error('hex string expected, got unpadded hex of length ' + hl);
const array = new Uint8Array(al);
for (let ai = 0, hi = 0; ai < al; ai++, hi += 2) {
const n1 = asciiToBase16(hex.charCodeAt(hi));
const n2 = asciiToBase16(hex.charCodeAt(hi + 1));
if (n1 === undefined || n2 === undefined) {
const char = hex[hi] + hex[hi + 1];
throw new Error('hex string expected, got non-hex character "' + char + '" at index ' + hi);
}
array[ai] = n1 * 16 + n2; // multiply first octet, e.g. 'a3' => 10*16+3 => 160 + 3 => 163
}
return array;
}
// BE: Big Endian, LE: Little Endian
export function bytesToNumberBE(bytes) {
return hexToNumber(bytesToHex(bytes));
}
export function bytesToNumberLE(bytes) {
abytes(bytes);
return hexToNumber(bytesToHex(Uint8Array.from(bytes).reverse()));
}
export function numberToBytesBE(n, len) {
return hexToBytes(n.toString(16).padStart(len * 2, '0'));
}
export function numberToBytesLE(n, len) {
return numberToBytesBE(n, len).reverse();
}
// Unpadded, rarely used
export function numberToVarBytesBE(n) {
return hexToBytes(numberToHexUnpadded(n));
}
/**
* Takes hex string or Uint8Array, converts to Uint8Array.
* Validates output length.
* Will throw error for other types.
* @param title descriptive title for an error e.g. 'private key'
* @param hex hex string or Uint8Array
* @param expectedLength optional, will compare to result array's length
* @returns
*/
export function ensureBytes(title, hex, expectedLength) {
let res;
if (typeof hex === 'string') {
try {
res = hexToBytes(hex);
}
catch (e) {
throw new Error(title + ' must be hex string or Uint8Array, cause: ' + e);
}
}
else if (isBytes(hex)) {
// Uint8Array.from() instead of hash.slice() because node.js Buffer
// is instance of Uint8Array, and its slice() creates **mutable** copy
res = Uint8Array.from(hex);
}
else {
throw new Error(title + ' must be hex string or Uint8Array');
}
const len = res.length;
if (typeof expectedLength === 'number' && len !== expectedLength)
throw new Error(title + ' of length ' + expectedLength + ' expected, got ' + len);
return res;
}
/**
* Copies several Uint8Arrays into one.
*/
export function concatBytes(...arrays) {
let sum = 0;
for (let i = 0; i < arrays.length; i++) {
const a = arrays[i];
abytes(a);
sum += a.length;
}
const res = new Uint8Array(sum);
for (let i = 0, pad = 0; i < arrays.length; i++) {
const a = arrays[i];
res.set(a, pad);
pad += a.length;
}
return res;
}
// Compares 2 u8a-s in kinda constant time
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;
}
/**
* @example utf8ToBytes('abc') // new Uint8Array([97, 98, 99])
*/
export function utf8ToBytes(str) {
if (typeof str !== 'string')
throw new Error('string expected');
return new Uint8Array(new TextEncoder().encode(str)); // https://bugzil.la/1681809
}
// Is positive bigint
const isPosBig = (n) => typeof n === 'bigint' && _0n <= n;
export function inRange(n, min, max) {
return isPosBig(n) && isPosBig(min) && isPosBig(max) && min <= n && n < max;
}
/**
* Asserts min <= n < max. NOTE: It's < max and not <= max.
* @example
* aInRange('x', x, 1n, 256n); // would assume x is in (1n..255n)
*/
export function aInRange(title, n, min, max) {
// Why min <= n < max and not a (min < n < max) OR b (min <= n <= max)?
// consider P=256n, min=0n, max=P
// - a for min=0 would require -1: `inRange('x', x, -1n, P)`
// - b would commonly require subtraction: `inRange('x', x, 0n, P - 1n)`
// - our way is the cleanest: `inRange('x', x, 0n, P)
if (!inRange(n, min, max))
throw new Error('expected valid ' + title + ': ' + min + ' <= n < ' + max + ', got ' + n);
}
// Bit operations
/**
* Calculates amount of bits in a bigint.
* Same as `n.toString(2).length`
*/
export function bitLen(n) {
let len;
for (len = 0; n > _0n; n >>= _1n, len += 1)
;
return len;
}
/**
* Gets single bit at position.
* NOTE: first bit position is 0 (same as arrays)
* Same as `!!+Array.from(n.toString(2)).reverse()[pos]`
*/
export function bitGet(n, pos) {
return (n >> BigInt(pos)) & _1n;
}
/**
* Sets single bit at position.
*/
export function bitSet(n, pos, value) {
return n | ((value ? _1n : _0n) << BigInt(pos));
}
/**
* Calculate mask for N bits. Not using ** operator with bigints because of old engines.
* Same as BigInt(`0b${Array(i).fill('1').join('')}`)
*/
export const bitMask = (n) => (_2n << BigInt(n - 1)) - _1n;
// DRBG
const u8n = (data) => new Uint8Array(data); // creates Uint8Array
const u8fr = (arr) => Uint8Array.from(arr); // another shortcut
/**
* Minimal HMAC-DRBG from NIST 800-90 for RFC6979 sigs.
* @returns function that will call DRBG until 2nd arg returns something meaningful
* @example
* const drbg = createHmacDRBG<Key>(32, 32, hmac);
* drbg(seed, bytesToKey); // bytesToKey must return Key or undefined
*/
export function createHmacDrbg(hashLen, qByteLen, hmacFn) {
if (typeof hashLen !== 'number' || hashLen < 2)
throw new Error('hashLen must be a number');
if (typeof qByteLen !== 'number' || qByteLen < 2)
throw new Error('qByteLen must be a number');
if (typeof hmacFn !== 'function')
throw new Error('hmacFn must be a function');
// Step B, Step C: set hashLen to 8*ceil(hlen/8)
let v = u8n(hashLen); // Minimal non-full-spec HMAC-DRBG from NIST 800-90 for RFC6979 sigs.
let k = u8n(hashLen); // Steps B and C of RFC6979 3.2: set hashLen, in our case always same
let i = 0; // Iterations counter, will throw when over 1000
const reset = () => {
v.fill(1);
k.fill(0);
i = 0;
};
const h = (...b) => hmacFn(k, v, ...b); // hmac(k)(v, ...values)
const reseed = (seed = u8n()) => {
// HMAC-DRBG reseed() function. Steps D-G
k = h(u8fr([0x00]), seed); // k = hmac(k || v || 0x00 || seed)
v = h(); // v = hmac(k || v)
if (seed.length === 0)
return;
k = h(u8fr([0x01]), seed); // k = hmac(k || v || 0x01 || seed)
v = h(); // v = hmac(k || v)
};
const gen = () => {
// HMAC-DRBG generate() function
if (i++ >= 1000)
throw new Error('drbg: tried 1000 values');
let len = 0;
const out = [];
while (len < qByteLen) {
v = h();
const sl = v.slice();
out.push(sl);
len += v.length;
}
return concatBytes(...out);
};
const genUntil = (seed, pred) => {
reset();
reseed(seed); // Steps D-G
let res = undefined; // Step H: grind until k is in [1..n-1]
while (!(res = pred(gen())))
reseed();
reset();
return res;
};
return genUntil;
}
// Validating curves and fields
const validatorFns = {
bigint: (val) => typeof val === 'bigint',
function: (val) => typeof val === 'function',
boolean: (val) => typeof val === 'boolean',
string: (val) => typeof val === 'string',
stringOrUint8Array: (val) => typeof val === 'string' || isBytes(val),
isSafeInteger: (val) => Number.isSafeInteger(val),
array: (val) => Array.isArray(val),
field: (val, object) => object.Fp.isValid(val),
hash: (val) => typeof val === 'function' && Number.isSafeInteger(val.outputLen),
};
// type Record<K extends string | number | symbol, T> = { [P in K]: T; }
export function validateObject(object, validators, optValidators = {}) {
const checkField = (fieldName, type, isOptional) => {
const checkVal = validatorFns[type];
if (typeof checkVal !== 'function')
throw new Error('invalid validator function');
const val = object[fieldName];
if (isOptional && val === undefined)
return;
if (!checkVal(val, object)) {
throw new Error('param ' + String(fieldName) + ' is invalid. Expected ' + type + ', got ' + val);
}
};
for (const [fieldName, type] of Object.entries(validators))
checkField(fieldName, type, false);
for (const [fieldName, type] of Object.entries(optValidators))
checkField(fieldName, type, true);
return object;
}
// validate type tests
// const o: { a: number; b: number; c: number } = { a: 1, b: 5, c: 6 };
// const z0 = validateObject(o, { a: 'isSafeInteger' }, { c: 'bigint' }); // Ok!
// // Should fail type-check
// const z1 = validateObject(o, { a: 'tmp' }, { c: 'zz' });
// const z2 = validateObject(o, { a: 'isSafeInteger' }, { c: 'zz' });
// const z3 = validateObject(o, { test: 'boolean', z: 'bug' });
// const z4 = validateObject(o, { a: 'boolean', z: 'bug' });
/**
* throws not implemented error
*/
export const notImplemented = () => {
throw new Error('not implemented');
};
/**
* Memoizes (caches) computation result.
* Uses WeakMap: the value is going auto-cleaned by GC after last reference is removed.
*/
export function memoized(fn) {
const map = new WeakMap();
return (arg, ...args) => {
const val = map.get(arg);
if (val !== undefined)
return val;
const computed = fn(arg, ...args);
map.set(arg, computed);
return computed;
};
}
//# sourceMappingURL=utils.js.map