Password Chameleon, the offline generator for site-specific passwords, uses the SHA-1 algorithm implemented in JavaScript to generate the hash (or the unique password).

/*
 * A JavaScript implementation of the Secure Hash Algorithm, SHA-1,
 * as defined in FIPS PUB 180-1
 * Version 2.1 Copyright Paul Johnston 2000 - 2002.
 * Other contributors: Greg Holt, Andrew Kepert, Ydnar, Lostinet
 * Distributed under the BSD License
 * See http://pajhome.org.uk/crypt/md5 for details.
 */

var b64pad = '';
var chrsz = 8;

function generate(secretpassword, sitename) {
  var pwd = '';
  var error = '';
  if (sitename.length == 0) error = error + ' sitename';
  if (secretpassword.length == 0) error = error + ' secretpassword';

  if (error.length == 0) {
    var input = secretpassword + ':' + sitename.toLowerCase();
    pwd = binb2b64(core_sha1(str2binb(input), input.length * chrsz));
    pwd = pwd.substring(0, 10);
    pwd = ensurenumberandletter(pwd);
  }
  return { password: pwd, error: error };
}

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

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

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

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

function binb2b64(binarray) {
  var tab = 'ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz123456789?!#@&$';
  var str = '';
  for (var i = 0; i < binarray.length * 4; i += 3) {
    var triplet =
      (((binarray[i >> 2] >> (8 * (3 - (i % 4)))) & 0xff) << 16) |
      (((binarray[(i + 1) >> 2] >> (8 * (3 - ((i + 1) % 4)))) & 0xff) << 8) |
      ((binarray[(i + 2) >> 2] >> (8 * (3 - ((i + 2) % 4)))) & 0xff);
    for (var j = 0; j < 4; j++) {
      if (i * 8 + j * 6 > binarray.length * 32) str += b64pad;
      else str += tab.charAt((triplet >> (6 * (3 - j))) & 0x3f);
    }
  }
  return str;
}

function ensurenumberandletter(s) {
  var numbers = '123456789';
  var letters = 'ABCDEFGHIJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz';
  var punct = '?!#@&$';
  var hasnumber = 0;
  var hasletter = 0;
  var haspunct = 0;

  for (var i = 0; i < s.length; i++) {
    if (numbers.indexOf(s[i]) > -1) hasnumber = 1;
    if (letters.indexOf(s[i]) > -1) hasletter = 1;
    if (punct.indexOf(s[i]) > -1) haspunct = 1;
  }
  if (hasnumber == 0) s = '1' + s.substring(1);
  if (hasletter == 0) s = s.substring(0, 1) + 'a' + s.substring(2);
  if (haspunct == 0) s = s.substring(0, 2) + '@' + s.substring(3);

  return s;
}