siphash/lib/siphash13.js

SipHash-2-4 fast short-input pseudo-random function

var SipHash13 = (function () {
    "use strict";
    function _add(a, b) {
        var rl = a.l + b.l, a2 = {
            h: a.h + b.h + (rl / 2 >>> 31) >>> 0,
            l: rl >>> 0
        };
        a.h = a2.h;
        a.l = a2.l;
    }
    function _xor(a, b) {
        a.h ^= b.h;
        a.h >>>= 0;
        a.l ^= b.l;
        a.l >>>= 0;
    }
    function _rotl(a, n) {
        var a2 = {
            h: a.h << n | a.l >>> (32 - n),
            l: a.l << n | a.h >>> (32 - n)
        };
        a.h = a2.h;
        a.l = a2.l;
    }
    function _rotl32(a) {
        var al = a.l;
        a.l = a.h;
        a.h = al;
    }
    function _compress(v0, v1, v2, v3) {
        _add(v0, v1);
        _add(v2, v3);
        _rotl(v1, 13);
        _rotl(v3, 16);
        _xor(v1, v0);
        _xor(v3, v2);
        _rotl32(v0);
        _add(v2, v1);
        _add(v0, v3);
        _rotl(v1, 17);
        _rotl(v3, 21);
        _xor(v1, v2);
        _xor(v3, v0);
        _rotl32(v2);
    }
    function _get_int(a, offset) {
        return a[offset + 3] << 24 |
            a[offset + 2] << 16 |
            a[offset + 1] << 8 |
            a[offset];
    }
    function hash(key, m) {
        if (typeof m === "string") {
            m = string_to_u8(m);
        }
        var k0 = {
            h: key[1] >>> 0,
            l: key[0] >>> 0
        }, k1 = {
            h: key[3] >>> 0,
            l: key[2] >>> 0
        }, v0 = {
            h: k0.h,
            l: k0.l
        }, v2 = k0, v1 = {
            h: k1.h,
            l: k1.l
        }, v3 = k1, ml = m.length, ml7 = ml - 7, buf = new Uint8Array(new ArrayBuffer(8));
        _xor(v0, {
            h: 0x736f6d65,
            l: 0x70736575
        });
        _xor(v1, {
            h: 0x646f7261,
            l: 0x6e646f6d
        });
        _xor(v2, {
            h: 0x6c796765,
            l: 0x6e657261
        });
        _xor(v3, {
            h: 0x74656462,
            l: 0x79746573
        });
        var mp = 0;
        while (mp < ml7) {
            var mi = {
                h: _get_int(m, mp + 4),
                l: _get_int(m, mp)
            };
            _xor(v3, mi);
            _compress(v0, v1, v2, v3);
            _xor(v0, mi);
            mp += 8;
        }
        buf[7] = ml;
        var ic = 0;
        while (mp < ml) {
            buf[ic++] = m[mp++];
        }
        while (ic < 7) {
            buf[ic++] = 0;
        }
        var mil = {
            h: buf[7] << 24 | buf[6] << 16 | buf[5] << 8 | buf[4],
            l: buf[3] << 24 | buf[2] << 16 | buf[1] << 8 | buf[0]
        };
        _xor(v3, mil);
        _compress(v0, v1, v2, v3);
        _xor(v0, mil);
        _xor(v2, {
            h: 0,
            l: 0xff
        });
        _compress(v0, v1, v2, v3);
        _compress(v0, v1, v2, v3);
        _compress(v0, v1, v2, v3);
        var h = v0;
        _xor(h, v1);
        _xor(h, v2);
        _xor(h, v3);
        return h;
    }
    function hash_hex(key, m) {
        var r = hash(key, m);
        return ("0000000" + r.h.toString(16)).substr(-8) +
            ("0000000" + r.l.toString(16)).substr(-8);
    }
    function hash_uint(key, m) {
        var r = hash(key, m);
        return (r.h & 0x1fffff) * 0x100000000 + r.l;
    }
    function string_to_u8(str) {
        if (typeof TextEncoder === "function") {
            return new TextEncoder().encode(str);
        }
        str = unescape(encodeURIComponent(str));
        var bytes = new Uint8Array(str.length);
        for (var i = 0, j = str.length; i < j; i++) {
            bytes[i] = str.charCodeAt(i);
        }
        return bytes;
    }
    function string16_to_key(str) {
        var u8 = string_to_u8(str);
        if (u8.length !== 16) {
            throw Error("Key length must be 16 bytes");
        }
        var key = new Uint32Array(4);
        key[0] = _get_int(u8, 0);
        key[1] = _get_int(u8, 4);
        key[2] = _get_int(u8, 8);
        key[3] = _get_int(u8, 12);
        return key;
    }
    return {
        hash: hash,
        hash_hex: hash_hex,
        hash_uint: hash_uint,
        string16_to_key: string16_to_key,
        string_to_u8: string_to_u8
    };
})();
module.exports = SipHash13;