148 lines
3.6 KiB
JavaScript
148 lines
3.6 KiB
JavaScript
import toArrayBuffer from 'to-arraybuffer'
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import { Buffer } from 'buffer' // 兼容浏览器环境
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import { leftShift } from './utils'
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// 官方文档以比特作为操作单位，此处以字节作为操作单位。
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const padding = (buf) => {
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// 首字节 0b10000000 填充
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const p1 = Buffer.alloc(1, 0x80)
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// 取值 "0" 的 k 比特填充
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let k = buf.length % 64 // 64 * 8 === 512
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k = k >= 56 ? 64 - (k % 56) - 1 : 56 - k - 1 // 56 * 8 === 448
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const p2 = Buffer.alloc(k, 0)
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// 64 比特(8 字节)的消息长度填充
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const p3 = Buffer.alloc(8)
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const size = buf.length * 8 // 不超过 2^53 -1
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p3.writeUInt32BE(Math.floor(size / 2 ** 32), 0) // 高 32 位
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p3.writeUInt32BE(size % 2 ** 32, 4) // 低 32 位
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return Buffer.concat([buf, p1, p2, p3], buf.length + 1 + k + 8)
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}
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const T = (j) => (j < 16 ? 0x79cc4519 : 0x7a879d8a)
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const FF = (X, Y, Z, j) => (j < 16 ? X ^ Y ^ Z : (X & Y) | (X & Z) | (Y & Z))
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const GG = (X, Y, Z, j) => (j < 16 ? X ^ Y ^ Z : (X & Y) | (~X & Z))
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const P0 = (X) => X ^ leftShift(X, 9) ^ leftShift(X, 17)
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const P1 = (X) => X ^ leftShift(X, 15) ^ leftShift(X, 23)
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// 消息扩展(512-bits): 16 个字 => 132 个字
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const extendFn = (Bi) => {
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const W = new Array(132)
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// 将消息分组 B(i) 划分为 16 个字 W0, W1, · · · , W15
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Bi.forEach((v, i) => {
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W[i] = v
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})
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/**
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FOR j=16 TO 67
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Wj ← P1(Wj−16 ⊕ Wj−9 ⊕ (Wj−3 ≪ 15)) ⊕ (Wj−13 ≪ 7) ⊕ Wj−6
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ENDFOR
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*/
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for (let j = 16; j < 68; j++) {
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W[j] =
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P1(W[j - 16] ^ W[j - 9] ^ leftShift(W[j - 3], 15)) ^
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leftShift(W[j - 13], 7) ^
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W[j - 6]
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}
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/**
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FOR j=0 TO 63
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W′j = Wj ⊕ Wj+4
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ENDFOR
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*/
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for (let j = 0; j < 64; j++) {
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W[j + 68] = W[j] ^ W[j + 4]
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}
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return W
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}
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// 压缩函数
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// - Vi => 8 个字(256-bits)
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// - Bi => 16 个字(512-bits)
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const CF = (Vi, Bi, i) => {
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const W = extendFn(Bi) // 消息扩展, 返回 132 个字
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let [A, B, C, D, E, F, G, H] = Vi
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let SS1, SS2, TT1, TT2
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for (let j = 0; j < 64; j++) {
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SS1 = leftShift(leftShift(A, 12) + E + leftShift(T(j), j), 7)
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SS2 = SS1 ^ leftShift(A, 12)
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TT1 = FF(A, B, C, j) + D + SS2 + W[j + 68]
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TT2 = GG(E, F, G, j) + H + SS1 + W[j]
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D = C
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C = leftShift(B, 9)
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B = A
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A = TT1
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H = G
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G = leftShift(F, 19)
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F = E
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E = P0(TT2)
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}
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return [
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A ^ Vi[0],
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B ^ Vi[1],
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C ^ Vi[2],
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D ^ Vi[3],
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E ^ Vi[4],
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F ^ Vi[5],
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G ^ Vi[6],
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H ^ Vi[7]
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]
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}
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export const digest = (data, inputEncoding, outputEncoding) => {
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// 输入参数校验 `string` | `ArrayBuffer` | `Buffer`
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if (typeof data === 'string') {
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data = Buffer.from(data, inputEncoding || 'utf8')
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} else if (data instanceof ArrayBuffer) {
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data = Buffer.from(data)
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}
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if (!Buffer.isBuffer(data)) {
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throw new TypeError(
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`Expected "string" | "Buffer" | "ArrayBuffer" but received "${Object.prototype.toString.call(
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data
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)}"`
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)
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}
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data = padding(data) // 数据填充
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const n = data.length / 64 // 512 比特对应 64 字节
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const B = new Array(n)
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for (let i = 0; i < n; i++) {
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B[i] = new Array(16)
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for (let j = 0; j < 16; j++) {
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const offset = i * 64 + j * 4
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B[i][j] = data.readUInt32BE(offset)
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}
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}
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const V = new Array(n)
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V[0] = [
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0x7380166f,
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0x4914b2b9,
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0x172442d7,
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0xda8a0600,
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0xa96f30bc,
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0x163138aa,
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0xe38dee4d,
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0xb0fb0e4e
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]
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// 迭代压缩
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for (let i = 0; i < n; i++) {
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V[i + 1] = CF(V[i], B[i], i)
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}
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const hash = Buffer.alloc(32)
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V[n].forEach((i32, j) => hash.writeInt32BE(i32, j * 4))
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return outputEncoding ? hash.toString(outputEncoding) : toArrayBuffer(hash)
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}
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