SHA-1的JavaScript实现（简化）

function sha1(message) {
  function rotateLeft(n, s) {
    return (n << s) | (n >>> (32 - s));
  }

  function toHex(value) {
    var hex = "";
    for (var i = 0; i < 8; i++) {
      hex += ((value >>> (28 - i * 4)) & 0xf).toString(16);
    }
    return hex;
  }

  function preProcessMessage(message) {
    var originalLength = message.length * 8;
    var appendedOne = 1 << 7;
    message.push(appendedOne);

    while (message.length % 64 !== 56) {
      message.push(0);
    }

    var lengthBytes = new Array(8);
    for (var i = 0; i < 8; i++) {
      lengthBytes[i] = (originalLength >>> (56 - i * 8)) & 0xff;
    }
    message = message.concat(lengthBytes);

    return message;
  }

  var h0 = 0x67452301;
  var h1 = 0xefcdab89;
  var h2 = 0x98badcfe;
  var h3 = 0x10325476;
  var h4 = 0xc3d2e1f0;

  var messageBytes = [];
  for (var i = 0; i < message.length; i++) {
    messageBytes.push(message.charCodeAt(i) & 0xff);
  }

  messageBytes = preProcessMessage(messageBytes);

  var blocks = messageBytes.length / 64;
  for (var i = 0; i < blocks; i++) {
    var words = new Array(80);
    for (var j = 0; j < 16; j++) {
      words[j] = (messageBytes[i * 64 + j * 4] << 24) |
                 (messageBytes[i * 64 + j * 4 + 1] << 16) |
                 (messageBytes[i * 64 + j * 4 + 2] << 8) |
                 (messageBytes[i * 64 + j * 4 + 3]);
    }

    for (var j = 16; j < 80; j++) {
      words[j] = rotateLeft((words[j - 3] ^ words[j - 8] ^ words[j - 14] ^ words[j - 16]), 1);
    }

    var a = h0;
    var b = h1;
    var c = h2;
    var d = h3;
    var e = h4;

    for (var j = 0; j < 80; j++) {
      var f, k;
      if (j < 20) {
        f = (b & c) | ((~b) & d);
        k = 0x5a827999;
      } else if (j < 40) {
        f = b ^ c ^ d;
        k = 0x6ed9eba1;
      } else if (j < 60) {
        f = (b & c) | (b & d) | (c & d);
        k = 0x8f1bbcdc;
      } else {
        f = b ^ c ^ d;
        k = 0xca62c1d6;
      }

      var temp = rotateLeft(a, 5) + f + e + k + words[j];
      e = d;
      d = c;
      c = rotateLeft(b, 30);
      b = a;
      a = temp;
    }

    h0 += a;
    h1 += b;
    h2 += c;
    h3 += d;
    h4 += e;
  }

  var hash = toHex(h0) + toHex(h1) + toHex(h2) + toHex(h3) + toHex(h4);
  return hash;
}

// 示例用法
var plaintext = "Hello, SHA-1!";
var hashedText = sha1(plaintext);
console.log("Hashed Text:", hashedText);