mina-painter/dist/weapp/painter-taro/lib/sha1.js

一个小程序图片生成库，轻松通过 json 方式绘制一张可以发到朋友圈的图片

let hexcase = 0;
let chrsz = 8;

export function hex_sha1(s) {
  return binb2hex(core_sha1(str2binb(s), s.length * chrsz));
}

function core_sha1(x, len) {
  x[len >> 5] |= 0x80 << (24 - (len % 32));
  x[(((len + 64) >> 9) << 4) + 15] = len;

  let w = Array(80);
  let a = 1732584193;
  let b = -271733879;
  let c = -1732584194;
  let d = 271733878;
  let e = -1009589776;

  for (let i = 0; i < x.length; i += 16) {
    let olda = a;
    let oldb = b;
    let oldc = c;
    let oldd = d;
    let olde = e;

    for (let j = 0; j < 80; j++) {
      if (j < 16) w[j] = x[i + j];
      else w[j] = rol(w[j - 3] ^ w[j - 8] ^ w[j - 14] ^ w[j - 16], 1);
      let t = safe_add(safe_add(rol(a, 5), sha1_ft(j, b, c, d)), safe_add(safe_add(e, w[j]), sha1_kt(j)));
      e = d;
      d = c;
      c = rol(b, 30);
      b = a;
      a = t;
    }

    a = safe_add(a, olda);
    b = safe_add(b, oldb);
    c = safe_add(c, oldc);
    d = safe_add(d, oldd);
    e = safe_add(e, olde);
  }
  return Array(a, b, c, d, e);
}

function sha1_ft(t, b, c, d) {
  if (t < 20) return (b & c) | (~b & d);
  if (t < 40) return b ^ c ^ d;
  if (t < 60) return (b & c) | (b & d) | (c & d);
  return b ^ c ^ d;
}

function sha1_kt(t) {
  return t < 20 ? 1518500249 : t < 40 ? 1859775393 : t < 60 ? -1894007588 : -899497514;
}

function safe_add(x, y) {
  let lsw = (x & 0xffff) + (y & 0xffff);
  let msw = (x >> 16) + (y >> 16) + (lsw >> 16);
  return (msw << 16) | (lsw & 0xffff);
}

function rol(num, cnt) {
  return (num << cnt) | (num >>> (32 - cnt));
}

function str2binb(str) {
  let bin = Array();
  let mask = (1 << chrsz) - 1;
  for (let i = 0; i < str.length * chrsz; i += chrsz)
    bin[i >> 5] |= (str.charCodeAt(i / chrsz) & mask) << (24 - (i % 32));
  return bin;
}

function binb2hex(binarray) {
  let hex_tab = hexcase ? '0123456789ABCDEF' : '0123456789abcdef';
  let str = '';
  for (let i = 0; i < binarray.length * 4; i++) {
    str +=
      hex_tab.charAt((binarray[i >> 2] >> ((3 - (i % 4)) * 8 + 4)) & 0xf) +
      hex_tab.charAt((binarray[i >> 2] >> ((3 - (i % 4)) * 8)) & 0xf);
  }
  return str;
}