Cipher for Minecraft lastlogin files implemented in JavaScript.

gistfile1.js

(function(a) {
  var j = [1056971584,1092420379, 222248973,1128348931, 239223324, 473841219,
            507790366,    924989, 457179966,1060977933,1092295748, 218317597,
           1075723843,1141775679, 239223296, 505151553],
      k = [1953896747, 688289143,2020897649,1982400117, 707557120,1897474930,
            746061866, 443773466,   2848041,2003989273,1920337524, 721820017,
            443754872, 746027052, 704673306,1903522858],
      n = [ 206766165,1442849110, 576215071,1411535372,1359237899, 542266657,
           1461722967,  72616785,1397826060, 525555200, 186799190,1477115989,
           1461670228,  69279832,1381436498, 553932064],
      t = [ 957682952, 926628886,   3552824, 151009852,  18036025, 137696788,
            989926458, 322385929, 977024568, 150994998, 339360513, 957682952,
            940114195,1008088891, 370423097, 137696055],
      v = [ 172443245, 654993734,1864845423,1835739241,1164865024,1886153800,
           1802502250,1195731496, 661457477,1766223215,1214868295,1862944107,
           1814588012,1174433386, 675835943,   7227248],
      w = [1751258980,1644520497,1714631016, 879124760,   3434263, 845612389,
           1694511971, 405955425,1711629618,1680939112, 828793112,1751396962,
            862126181,  85418547, 389310208,1667314791],
      x = [ 760041216, 256847691,1278017616,  38358288,1311715406,1347046192,
           1242501196, 771901742,1227763023,1330466050, 810110509,1259351883,
            273697866, 771752524,   3099151,1347292976],
      y = [1594958684,1499400025, 643456036,1529155847,1516264978, 606494043,
            301989981,1616782627, 623074065, 123539749,1577541722,1566122847,
              6039136,1516134144,1545872402, 304503131], 
      z = [ 169287213, 236724513, 889459721,1043930168, 254288666, 302986752,
            222238508, 605366540, 335741730, 959253547,1059391543, 137248032,
            320025114, 639041851, 339286801, 488312581,
            255336493, 187055880, 573252874, 624235567, 907086649, 976749828,
            453784352, 322844721, 723192378, 336796204, 471995678, 523308336,
            772673842, 942019331, 589762096, 555431438],
      A = [0, NaN, 3, 2, 1, 6, 7, 4, 5, 10, 9, 12, 8, 15, 11, 14, 13, 16, 19,
           21, 17, 18, 22, 25, 20], B = [0], C = 47, D = String.fromCharCode,
      E = function(d) {
        return[d].concat(isNaN(A[d - 7]) ? [] : E(A[d - 7])) },
      F = function(d) {
        var e = [Math.pow(2, d) * (31 <= d ? -1 : 1)];
        d = isNaN(A[d - 7]) ? [] : E(A[d - 7]);
        for(var f = 0;f < d.length;f++) 
          for(var b = F(d[f]), h = 0;h < b.length;h++)
            e.push(e[0] + b[h]);
        return e },
      G = function(d) {
        for(var e = C, f = 0;4 > f;f++)
          d[4 * e + (3 - f)] = B[d[e] >> 8 * f & 255] },
      H = function(d, e) {
        var f = d.length, b = 8 - f % 8;
        e && (d += D(b, b, b, b, b, b, b, b), 8 == b && (f += 8));
        for(var h = -1073379694, r = -328741063,
                p = "", u = "", s = 0, g = 0, I, J;g < f;) {
          A = d.charCodeAt(g++) << 24 | d.charCodeAt(g++) << 16
            | d.charCodeAt(g++) <<  8 | d.charCodeAt(g++);
          c = d.charCodeAt(g++) << 24 | d.charCodeAt(g++) << 16
            | d.charCodeAt(g++) <<  8 | d.charCodeAt(g++);
            
          e ? (A ^= h, c ^= r) : (I = h, J = r, h = A, r = c);
          
          b = (A >>>  4 ^ c) &  252645135; c ^= b; A ^= b <<  4;
          b = (A >>> 16 ^ c) &      65535; c ^= b; A ^= b << 16;
          b = (c >>>  2 ^ A) &  858993459; A ^= b; c ^= b <<  2;
          b = (c >>>  8 ^ A) &   16711935; A ^= b; c ^= b <<  8;
          b = (A >>>  1 ^ c) & 1431655765; c ^= b; A ^= b <<  1;
          
          A = A << 1 | A >>> 31;
          c = c << 1 | c >>> 31;
          
          for(var q = e ? 0 : 30, K = e ? 32 : -2, L = e ? 2 : -2;q != K;q += L)
            m = c ^ z[q], l = (c >>> 4 | c << 28) ^ z[q + 1], b = A, A = c,
            c = b ^ (k[m >>> 24 & 63] | t[m >>> 16 & 63] | w[m >>> 8 & 63] | y[m & 63]
                  |  j[l >>> 24 & 63] | n[l >>> 16 & 63] | v[l >>> 8 & 63] | x[l & 63]);
          
          b = A; A = c; c = b;
          
          A = A >>> 1 | A << 31;
          c = c >>> 1 | c << 31;
          
          b = (A >>>  1 ^ c) & 1431655765; c ^= b; A ^= b <<  1;
          b = (c >>>  8 ^ A) &   16711935; A ^= b; c ^= b <<  8;
          b = (c >>>  2 ^ A) &  858993459; A ^= b; c ^= b <<  2;
          b = (A >>> 16 ^ c) &      65535; c ^= b; A ^= b << 16;
          b = (A >>>  4 ^ c) &  252645135; c ^= b; A ^= b <<  4;
          
          e ? (h = A, r = c) : (A ^= I, c ^= J);
          
          p += D(A >>> 24, A >>> 16 & 255, A >>> 8 & 255, A & 255,
                 c >>> 24, c >>> 16 & 255, c >>> 8 & 255, c & 255);
          
          s += 8; 512 == s && (u += p, p = "", s = 0)
        }
        return u + p }
  for(; 16 <= C; C--) B = B.concat(F(47 - C));
  for(;  0 <= C; C--) G(j), G(k), G(n), G(t), G(v), G(w), G(x), G(y);
  a.mcll_encrypt = function(d, e) {
    d instanceof Array && (e = d[1], d = d[0]); e = e || "";
    return H(D(d.length >> 8 & 255) + D(d.length & 255) + d +
             D(e.length >> 8 & 255) + D(e.length & 255) + e, !0) }
  a.mcll_decrypt = function(d) {
    var e = ((d = H(d, !1)).charCodeAt(   ) << 8) + d.charCodeAt(1)
    return [d.substr(2, e), d.substr(e += 3,
                         (d.charCodeAt(e++) << 8) + d.charCodeAt(e))]}
})(window)