173 lines
5.1 KiB
JavaScript
173 lines
5.1 KiB
JavaScript
/**
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* @module sha256
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* Spec: https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.180-4.pdf
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* Resources:
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* - https://web.archive.org/web/20150315061807/http://csrc.nist.gov/groups/STM/cavp/documents/shs/sha256-384-512.pdf
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*/
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import * as binary from '../binary.js'
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/**
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* @param {number} w - a 32bit uint
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* @param {number} shift
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*/
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const rotr = (w, shift) => (w >>> shift) | (w << (32 - shift))
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/**
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* Helper for SHA-224 & SHA-256. See 4.1.2.
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* @param {number} x
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*/
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const sum0to256 = x => rotr(x, 2) ^ rotr(x, 13) ^ rotr(x, 22)
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/**
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* Helper for SHA-224 & SHA-256. See 4.1.2.
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* @param {number} x
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*/
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const sum1to256 = x => rotr(x, 6) ^ rotr(x, 11) ^ rotr(x, 25)
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/**
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* Helper for SHA-224 & SHA-256. See 4.1.2.
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* @param {number} x
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*/
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const sigma0to256 = x => rotr(x, 7) ^ rotr(x, 18) ^ x >>> 3
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/**
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* Helper for SHA-224 & SHA-256. See 4.1.2.
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* @param {number} x
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*/
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const sigma1to256 = x => rotr(x, 17) ^ rotr(x, 19) ^ x >>> 10
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// @todo don't init these variables globally
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/**
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* See 4.2.2: Constant for sha256 & sha224
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* These words represent the first thirty-two bits of the fractional parts of
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* the cube roots of the first sixty-four prime numbers. In hex, these constant words are (from left to
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* right)
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*/
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const K = new Uint32Array([
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0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
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0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
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0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
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0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
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0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
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0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
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0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
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0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
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])
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/**
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* See 5.3.3. Initial hash value.
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*
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* These words were obtained by taking the first thirty-two bits of the fractional parts of the
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* square roots of the first eight prime numbers.
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*
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* @todo shouldn't be a global variable
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*/
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const HINIT = new Uint32Array([
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0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19
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])
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// time to beat: (large value < 4.35s)
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class Hasher {
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constructor () {
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const buf = new ArrayBuffer(64 + 64 * 4)
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// Init working variables using a single arraybuffer
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this._H = new Uint32Array(buf, 0, 8)
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this._H.set(HINIT)
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// "Message schedule" - a working variable
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this._W = new Uint32Array(buf, 64, 64)
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}
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_updateHash () {
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const H = this._H
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const W = this._W
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for (let t = 16; t < 64; t++) {
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W[t] = sigma1to256(W[t - 2]) + W[t - 7] + sigma0to256(W[t - 15]) + W[t - 16]
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}
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let a = H[0]
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let b = H[1]
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let c = H[2]
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let d = H[3]
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let e = H[4]
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let f = H[5]
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let g = H[6]
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let h = H[7]
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for (let tt = 0, T1, T2; tt < 64; tt++) {
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T1 = (h + sum1to256(e) + ((e & f) ^ (~e & g)) + K[tt] + W[tt]) >>> 0
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T2 = (sum0to256(a) + ((a & b) ^ (a & c) ^ (b & c))) >>> 0
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h = g
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g = f
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f = e
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e = (d + T1) >>> 0
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d = c
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c = b
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b = a
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a = (T1 + T2) >>> 0
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}
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H[0] += a
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H[1] += b
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H[2] += c
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H[3] += d
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H[4] += e
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H[5] += f
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H[6] += g
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H[7] += h
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}
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/**
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* @param {Uint8Array} data
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*/
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digest (data) {
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let i = 0
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for (; i + 56 <= data.length;) {
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// write data in big endianess
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let j = 0
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for (; j < 16 && i + 3 < data.length; j++) {
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this._W[j] = data[i++] << 24 | data[i++] << 16 | data[i++] << 8 | data[i++]
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}
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if (i % 64 !== 0) { // there is still room to write partial content and the ending bit.
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this._W.fill(0, j, 16)
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while (i < data.length) {
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this._W[j] |= data[i] << ((3 - (i % 4)) * 8)
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i++
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}
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this._W[j] |= binary.BIT8 << ((3 - (i % 4)) * 8)
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}
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this._updateHash()
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}
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// same check as earlier - the ending bit has been written
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const isPaddedWith1 = i % 64 !== 0
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this._W.fill(0, 0, 16)
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let j = 0
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for (; i < data.length; j++) {
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for (let ci = 3; ci >= 0 && i < data.length; ci--) {
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this._W[j] |= data[i++] << (ci * 8)
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}
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}
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// Write padding of the message. See 5.1.2.
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if (!isPaddedWith1) {
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this._W[j - (i % 4 === 0 ? 0 : 1)] |= binary.BIT8 << ((3 - (i % 4)) * 8)
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}
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// write length of message (size in bits) as 64 bit uint
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// @todo test that this works correctly
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this._W[14] = data.byteLength / binary.BIT30 // same as data.byteLength >>> 30 - but works on floats
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this._W[15] = data.byteLength * 8
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this._updateHash()
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// correct H endianness to use big endiannes and return a Uint8Array
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const dv = new Uint8Array(32)
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for (let i = 0; i < this._H.length; i++) {
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for (let ci = 0; ci < 4; ci++) {
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dv[i * 4 + ci] = this._H[i] >>> (3 - ci) * 8
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}
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}
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return dv
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}
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}
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/**
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* @param {Uint8Array} data
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*/
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export const digest = data => new Hasher().digest(data)
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