/*
 * Copyright (C) 2019 The Turms Project
 * https://github.com/turms-im/turms
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.bouncycastle.crypto.generators;

import java.util.Arrays;

import org.bouncycastle.util.Pack;

/**
 * Core of password hashing scheme Bcrypt, designed by Niels Provos and David Mazières, corresponds
 * to the C reference implementation.
 * <p>
 * This implementation does not correspondent to the 1999 published paper "A Future-Adaptable
 * Password Scheme" of Niels Provos and David Mazières, see:
 * https://www.usenix.org/legacy/events/usenix99/provos/provos_html/node1.html. In contrast to the
 * paper, the order of key setup and salt setup is reversed: state &lt;- ExpandKey(state, 0, key)
 * state &lt;- ExpandKey(state, 0, salt) This corresponds to the OpenBSD reference implementation of
 * Bcrypt.
 * </p>
 * <p>
 * Note: There is no successful cryptanalysis (status 2015), but the amount of memory and the band
 * width of Bcrypt may be insufficient to effectively prevent attacks with custom hardware like
 * FPGAs, ASICs
 * </p>
 * <p>
 * This implementation uses some parts of Bouncy Castle's BlowfishEngine.
 * </p>
 */
public final class BCrypt {
    // magic String "OrpheanBeholderScryDoubt" is used as clear text for encryption
    private static final int[] MAGIC_STRING =
            {0x4F727068, 0x65616E42, 0x65686F6C, 0x64657253, 0x63727944, 0x6F756274};
    final static int MAGIC_STRING_LENGTH = 6;

    private final static int[] KP =
            {0x243F6A88,
                    0x85A308D3,
                    0x13198A2E,
                    0x03707344,
                    0xA4093822,
                    0x299F31D0,
                    0x082EFA98,
                    0xEC4E6C89,
                    0x452821E6,
                    0x38D01377,
                    0xBE5466CF,
                    0x34E90C6C,
                    0xC0AC29B7,
                    0xC97C50DD,
                    0x3F84D5B5,
                    0xB5470917,
                    0x9216D5D9,
                    0x8979FB1B},

            KS0 = {0xD1310BA6,
                    0x98DFB5AC,
                    0x2FFD72DB,
                    0xD01ADFB7,
                    0xB8E1AFED,
                    0x6A267E96,
                    0xBA7C9045,
                    0xF12C7F99,
                    0x24A19947,
                    0xB3916CF7,
                    0x0801F2E2,
                    0x858EFC16,
                    0x636920D8,
                    0x71574E69,
                    0xA458FEA3,
                    0xF4933D7E,
                    0x0D95748F,
                    0x728EB658,
                    0x718BCD58,
                    0x82154AEE,
                    0x7B54A41D,
                    0xC25A59B5,
                    0x9C30D539,
                    0x2AF26013,
                    0xC5D1B023,
                    0x286085F0,
                    0xCA417918,
                    0xB8DB38EF,
                    0x8E79DCB0,
                    0x603A180E,
                    0x6C9E0E8B,
                    0xB01E8A3E,
                    0xD71577C1,
                    0xBD314B27,
                    0x78AF2FDA,
                    0x55605C60,
                    0xE65525F3,
                    0xAA55AB94,
                    0x57489862,
                    0x63E81440,
                    0x55CA396A,
                    0x2AAB10B6,
                    0xB4CC5C34,
                    0x1141E8CE,
                    0xA15486AF,
                    0x7C72E993,
                    0xB3EE1411,
                    0x636FBC2A,
                    0x2BA9C55D,
                    0x741831F6,
                    0xCE5C3E16,
                    0x9B87931E,
                    0xAFD6BA33,
                    0x6C24CF5C,
                    0x7A325381,
                    0x28958677,
                    0x3B8F4898,
                    0x6B4BB9AF,
                    0xC4BFE81B,
                    0x66282193,
                    0x61D809CC,
                    0xFB21A991,
                    0x487CAC60,
                    0x5DEC8032,
                    0xEF845D5D,
                    0xE98575B1,
                    0xDC262302,
                    0xEB651B88,
                    0x23893E81,
                    0xD396ACC5,
                    0x0F6D6FF3,
                    0x83F44239,
                    0x2E0B4482,
                    0xA4842004,
                    0x69C8F04A,
                    0x9E1F9B5E,
                    0x21C66842,
                    0xF6E96C9A,
                    0x670C9C61,
                    0xABD388F0,
                    0x6A51A0D2,
                    0xD8542F68,
                    0x960FA728,
                    0xAB5133A3,
                    0x6EEF0B6C,
                    0x137A3BE4,
                    0xBA3BF050,
                    0x7EFB2A98,
                    0xA1F1651D,
                    0x39AF0176,
                    0x66CA593E,
                    0x82430E88,
                    0x8CEE8619,
                    0x456F9FB4,
                    0x7D84A5C3,
                    0x3B8B5EBE,
                    0xE06F75D8,
                    0x85C12073,
                    0x401A449F,
                    0x56C16AA6,
                    0x4ED3AA62,
                    0x363F7706,
                    0x1BFEDF72,
                    0x429B023D,
                    0x37D0D724,
                    0xD00A1248,
                    0xDB0FEAD3,
                    0x49F1C09B,
                    0x075372C9,
                    0x80991B7B,
                    0x25D479D8,
                    0xF6E8DEF7,
                    0xE3FE501A,
                    0xB6794C3B,
                    0x976CE0BD,
                    0x04C006BA,
                    0xC1A94FB6,
                    0x409F60C4,
                    0x5E5C9EC2,
                    0x196A2463,
                    0x68FB6FAF,
                    0x3E6C53B5,
                    0x1339B2EB,
                    0x3B52EC6F,
                    0x6DFC511F,
                    0x9B30952C,
                    0xCC814544,
                    0xAF5EBD09,
                    0xBEE3D004,
                    0xDE334AFD,
                    0x660F2807,
                    0x192E4BB3,
                    0xC0CBA857,
                    0x45C8740F,
                    0xD20B5F39,
                    0xB9D3FBDB,
                    0x5579C0BD,
                    0x1A60320A,
                    0xD6A100C6,
                    0x402C7279,
                    0x679F25FE,
                    0xFB1FA3CC,
                    0x8EA5E9F8,
                    0xDB3222F8,
                    0x3C7516DF,
                    0xFD616B15,
                    0x2F501EC8,
                    0xAD0552AB,
                    0x323DB5FA,
                    0xFD238760,
                    0x53317B48,
                    0x3E00DF82,
                    0x9E5C57BB,
                    0xCA6F8CA0,
                    0x1A87562E,
                    0xDF1769DB,
                    0xD542A8F6,
                    0x287EFFC3,
                    0xAC6732C6,
                    0x8C4F5573,
                    0x695B27B0,
                    0xBBCA58C8,
                    0xE1FFA35D,
                    0xB8F011A0,
                    0x10FA3D98,
                    0xFD2183B8,
                    0x4AFCB56C,
                    0x2DD1D35B,
                    0x9A53E479,
                    0xB6F84565,
                    0xD28E49BC,
                    0x4BFB9790,
                    0xE1DDF2DA,
                    0xA4CB7E33,
                    0x62FB1341,
                    0xCEE4C6E8,
                    0xEF20CADA,
                    0x36774C01,
                    0xD07E9EFE,
                    0x2BF11FB4,
                    0x95DBDA4D,
                    0xAE909198,
                    0xEAAD8E71,
                    0x6B93D5A0,
                    0xD08ED1D0,
                    0xAFC725E0,
                    0x8E3C5B2F,
                    0x8E7594B7,
                    0x8FF6E2FB,
                    0xF2122B64,
                    0x8888B812,
                    0x900DF01C,
                    0x4FAD5EA0,
                    0x688FC31C,
                    0xD1CFF191,
                    0xB3A8C1AD,
                    0x2F2F2218,
                    0xBE0E1777,
                    0xEA752DFE,
                    0x8B021FA1,
                    0xE5A0CC0F,
                    0xB56F74E8,
                    0x18ACF3D6,
                    0xCE89E299,
                    0xB4A84FE0,
                    0xFD13E0B7,
                    0x7CC43B81,
                    0xD2ADA8D9,
                    0x165FA266,
                    0x80957705,
                    0x93CC7314,
                    0x211A1477,
                    0xE6AD2065,
                    0x77B5FA86,
                    0xC75442F5,
                    0xFB9D35CF,
                    0xEBCDAF0C,
                    0x7B3E89A0,
                    0xD6411BD3,
                    0xAE1E7E49,
                    0x00250E2D,
                    0x2071B35E,
                    0x226800BB,
                    0x57B8E0AF,
                    0x2464369B,
                    0xF009B91E,
                    0x5563911D,
                    0x59DFA6AA,
                    0x78C14389,
                    0xD95A537F,
                    0x207D5BA2,
                    0x02E5B9C5,
                    0x83260376,
                    0x6295CFA9,
                    0x11C81968,
                    0x4E734A41,
                    0xB3472DCA,
                    0x7B14A94A,
                    0x1B510052,
                    0x9A532915,
                    0xD60F573F,
                    0xBC9BC6E4,
                    0x2B60A476,
                    0x81E67400,
                    0x08BA6FB5,
                    0x571BE91F,
                    0xF296EC6B,
                    0x2A0DD915,
                    0xB6636521,
                    0xE7B9F9B6,
                    0xFF34052E,
                    0xC5855664,
                    0x53B02D5D,
                    0xA99F8FA1,
                    0x08BA4799,
                    0x6E85076A},

            KS1 = {0x4B7A70E9,
                    0xB5B32944,
                    0xDB75092E,
                    0xC4192623,
                    0xAD6EA6B0,
                    0x49A7DF7D,
                    0x9CEE60B8,
                    0x8FEDB266,
                    0xECAA8C71,
                    0x699A17FF,
                    0x5664526C,
                    0xC2B19EE1,
                    0x193602A5,
                    0x75094C29,
                    0xA0591340,
                    0xE4183A3E,
                    0x3F54989A,
                    0x5B429D65,
                    0x6B8FE4D6,
                    0x99F73FD6,
                    0xA1D29C07,
                    0xEFE830F5,
                    0x4D2D38E6,
                    0xF0255DC1,
                    0x4CDD2086,
                    0x8470EB26,
                    0x6382E9C6,
                    0x021ECC5E,
                    0x09686B3F,
                    0x3EBAEFC9,
                    0x3C971814,
                    0x6B6A70A1,
                    0x687F3584,
                    0x52A0E286,
                    0xB79C5305,
                    0xAA500737,
                    0x3E07841C,
                    0x7FDEAE5C,
                    0x8E7D44EC,
                    0x5716F2B8,
                    0xB03ADA37,
                    0xF0500C0D,
                    0xF01C1F04,
                    0x0200B3FF,
                    0xAE0CF51A,
                    0x3CB574B2,
                    0x25837A58,
                    0xDC0921BD,
                    0xD19113F9,
                    0x7CA92FF6,
                    0x94324773,
                    0x22F54701,
                    0x3AE5E581,
                    0x37C2DADC,
                    0xC8B57634,
                    0x9AF3DDA7,
                    0xA9446146,
                    0x0FD0030E,
                    0xECC8C73E,
                    0xA4751E41,
                    0xE238CD99,
                    0x3BEA0E2F,
                    0x3280BBA1,
                    0x183EB331,
                    0x4E548B38,
                    0x4F6DB908,
                    0x6F420D03,
                    0xF60A04BF,
                    0x2CB81290,
                    0x24977C79,
                    0x5679B072,
                    0xBCAF89AF,
                    0xDE9A771F,
                    0xD9930810,
                    0xB38BAE12,
                    0xDCCF3F2E,
                    0x5512721F,
                    0x2E6B7124,
                    0x501ADDE6,
                    0x9F84CD87,
                    0x7A584718,
                    0x7408DA17,
                    0xBC9F9ABC,
                    0xE94B7D8C,
                    0xEC7AEC3A,
                    0xDB851DFA,
                    0x63094366,
                    0xC464C3D2,
                    0xEF1C1847,
                    0x3215D908,
                    0xDD433B37,
                    0x24C2BA16,
                    0x12A14D43,
                    0x2A65C451,
                    0x50940002,
                    0x133AE4DD,
                    0x71DFF89E,
                    0x10314E55,
                    0x81AC77D6,
                    0x5F11199B,
                    0x043556F1,
                    0xD7A3C76B,
                    0x3C11183B,
                    0x5924A509,
                    0xF28FE6ED,
                    0x97F1FBFA,
                    0x9EBABF2C,
                    0x1E153C6E,
                    0x86E34570,
                    0xEAE96FB1,
                    0x860E5E0A,
                    0x5A3E2AB3,
                    0x771FE71C,
                    0x4E3D06FA,
                    0x2965DCB9,
                    0x99E71D0F,
                    0x803E89D6,
                    0x5266C825,
                    0x2E4CC978,
                    0x9C10B36A,
                    0xC6150EBA,
                    0x94E2EA78,
                    0xA5FC3C53,
                    0x1E0A2DF4,
                    0xF2F74EA7,
                    0x361D2B3D,
                    0x1939260F,
                    0x19C27960,
                    0x5223A708,
                    0xF71312B6,
                    0xEBADFE6E,
                    0xEAC31F66,
                    0xE3BC4595,
                    0xA67BC883,
                    0xB17F37D1,
                    0x018CFF28,
                    0xC332DDEF,
                    0xBE6C5AA5,
                    0x65582185,
                    0x68AB9802,
                    0xEECEA50F,
                    0xDB2F953B,
                    0x2AEF7DAD,
                    0x5B6E2F84,
                    0x1521B628,
                    0x29076170,
                    0xECDD4775,
                    0x619F1510,
                    0x13CCA830,
                    0xEB61BD96,
                    0x0334FE1E,
                    0xAA0363CF,
                    0xB5735C90,
                    0x4C70A239,
                    0xD59E9E0B,
                    0xCBAADE14,
                    0xEECC86BC,
                    0x60622CA7,
                    0x9CAB5CAB,
                    0xB2F3846E,
                    0x648B1EAF,
                    0x19BDF0CA,
                    0xA02369B9,
                    0x655ABB50,
                    0x40685A32,
                    0x3C2AB4B3,
                    0x319EE9D5,
                    0xC021B8F7,
                    0x9B540B19,
                    0x875FA099,
                    0x95F7997E,
                    0x623D7DA8,
                    0xF837889A,
                    0x97E32D77,
                    0x11ED935F,
                    0x16681281,
                    0x0E358829,
                    0xC7E61FD6,
                    0x96DEDFA1,
                    0x7858BA99,
                    0x57F584A5,
                    0x1B227263,
                    0x9B83C3FF,
                    0x1AC24696,
                    0xCDB30AEB,
                    0x532E3054,
                    0x8FD948E4,
                    0x6DBC3128,
                    0x58EBF2EF,
                    0x34C6FFEA,
                    0xFE28ED61,
                    0xEE7C3C73,
                    0x5D4A14D9,
                    0xE864B7E3,
                    0x42105D14,
                    0x203E13E0,
                    0x45EEE2B6,
                    0xA3AAABEA,
                    0xDB6C4F15,
                    0xFACB4FD0,
                    0xC742F442,
                    0xEF6ABBB5,
                    0x654F3B1D,
                    0x41CD2105,
                    0xD81E799E,
                    0x86854DC7,
                    0xE44B476A,
                    0x3D816250,
                    0xCF62A1F2,
                    0x5B8D2646,
                    0xFC8883A0,
                    0xC1C7B6A3,
                    0x7F1524C3,
                    0x69CB7492,
                    0x47848A0B,
                    0x5692B285,
                    0x095BBF00,
                    0xAD19489D,
                    0x1462B174,
                    0x23820E00,
                    0x58428D2A,
                    0x0C55F5EA,
                    0x1DADF43E,
                    0x233F7061,
                    0x3372F092,
                    0x8D937E41,
                    0xD65FECF1,
                    0x6C223BDB,
                    0x7CDE3759,
                    0xCBEE7460,
                    0x4085F2A7,
                    0xCE77326E,
                    0xA6078084,
                    0x19F8509E,
                    0xE8EFD855,
                    0x61D99735,
                    0xA969A7AA,
                    0xC50C06C2,
                    0x5A04ABFC,
                    0x800BCADC,
                    0x9E447A2E,
                    0xC3453484,
                    0xFDD56705,
                    0x0E1E9EC9,
                    0xDB73DBD3,
                    0x105588CD,
                    0x675FDA79,
                    0xE3674340,
                    0xC5C43465,
                    0x713E38D8,
                    0x3D28F89E,
                    0xF16DFF20,
                    0x153E21E7,
                    0x8FB03D4A,
                    0xE6E39F2B,
                    0xDB83ADF7},

            KS2 = {0xE93D5A68,
                    0x948140F7,
                    0xF64C261C,
                    0x94692934,
                    0x411520F7,
                    0x7602D4F7,
                    0xBCF46B2E,
                    0xD4A20068,
                    0xD4082471,
                    0x3320F46A,
                    0x43B7D4B7,
                    0x500061AF,
                    0x1E39F62E,
                    0x97244546,
                    0x14214F74,
                    0xBF8B8840,
                    0x4D95FC1D,
                    0x96B591AF,
                    0x70F4DDD3,
                    0x66A02F45,
                    0xBFBC09EC,
                    0x03BD9785,
                    0x7FAC6DD0,
                    0x31CB8504,
                    0x96EB27B3,
                    0x55FD3941,
                    0xDA2547E6,
                    0xABCA0A9A,
                    0x28507825,
                    0x530429F4,
                    0x0A2C86DA,
                    0xE9B66DFB,
                    0x68DC1462,
                    0xD7486900,
                    0x680EC0A4,
                    0x27A18DEE,
                    0x4F3FFEA2,
                    0xE887AD8C,
                    0xB58CE006,
                    0x7AF4D6B6,
                    0xAACE1E7C,
                    0xD3375FEC,
                    0xCE78A399,
                    0x406B2A42,
                    0x20FE9E35,
                    0xD9F385B9,
                    0xEE39D7AB,
                    0x3B124E8B,
                    0x1DC9FAF7,
                    0x4B6D1856,
                    0x26A36631,
                    0xEAE397B2,
                    0x3A6EFA74,
                    0xDD5B4332,
                    0x6841E7F7,
                    0xCA7820FB,
                    0xFB0AF54E,
                    0xD8FEB397,
                    0x454056AC,
                    0xBA489527,
                    0x55533A3A,
                    0x20838D87,
                    0xFE6BA9B7,
                    0xD096954B,
                    0x55A867BC,
                    0xA1159A58,
                    0xCCA92963,
                    0x99E1DB33,
                    0xA62A4A56,
                    0x3F3125F9,
                    0x5EF47E1C,
                    0x9029317C,
                    0xFDF8E802,
                    0x04272F70,
                    0x80BB155C,
                    0x05282CE3,
                    0x95C11548,
                    0xE4C66D22,
                    0x48C1133F,
                    0xC70F86DC,
                    0x07F9C9EE,
                    0x41041F0F,
                    0x404779A4,
                    0x5D886E17,
                    0x325F51EB,
                    0xD59BC0D1,
                    0xF2BCC18F,
                    0x41113564,
                    0x257B7834,
                    0x602A9C60,
                    0xDFF8E8A3,
                    0x1F636C1B,
                    0x0E12B4C2,
                    0x02E1329E,
                    0xAF664FD1,
                    0xCAD18115,
                    0x6B2395E0,
                    0x333E92E1,
                    0x3B240B62,
                    0xEEBEB922,
                    0x85B2A20E,
                    0xE6BA0D99,
                    0xDE720C8C,
                    0x2DA2F728,
                    0xD0127845,
                    0x95B794FD,
                    0x647D0862,
                    0xE7CCF5F0,
                    0x5449A36F,
                    0x877D48FA,
                    0xC39DFD27,
                    0xF33E8D1E,
                    0x0A476341,
                    0x992EFF74,
                    0x3A6F6EAB,
                    0xF4F8FD37,
                    0xA812DC60,
                    0xA1EBDDF8,
                    0x991BE14C,
                    0xDB6E6B0D,
                    0xC67B5510,
                    0x6D672C37,
                    0x2765D43B,
                    0xDCD0E804,
                    0xF1290DC7,
                    0xCC00FFA3,
                    0xB5390F92,
                    0x690FED0B,
                    0x667B9FFB,
                    0xCEDB7D9C,
                    0xA091CF0B,
                    0xD9155EA3,
                    0xBB132F88,
                    0x515BAD24,
                    0x7B9479BF,
                    0x763BD6EB,
                    0x37392EB3,
                    0xCC115979,
                    0x8026E297,
                    0xF42E312D,
                    0x6842ADA7,
                    0xC66A2B3B,
                    0x12754CCC,
                    0x782EF11C,
                    0x6A124237,
                    0xB79251E7,
                    0x06A1BBE6,
                    0x4BFB6350,
                    0x1A6B1018,
                    0x11CAEDFA,
                    0x3D25BDD8,
                    0xE2E1C3C9,
                    0x44421659,
                    0x0A121386,
                    0xD90CEC6E,
                    0xD5ABEA2A,
                    0x64AF674E,
                    0xDA86A85F,
                    0xBEBFE988,
                    0x64E4C3FE,
                    0x9DBC8057,
                    0xF0F7C086,
                    0x60787BF8,
                    0x6003604D,
                    0xD1FD8346,
                    0xF6381FB0,
                    0x7745AE04,
                    0xD736FCCC,
                    0x83426B33,
                    0xF01EAB71,
                    0xB0804187,
                    0x3C005E5F,
                    0x77A057BE,
                    0xBDE8AE24,
                    0x55464299,
                    0xBF582E61,
                    0x4E58F48F,
                    0xF2DDFDA2,
                    0xF474EF38,
                    0x8789BDC2,
                    0x5366F9C3,
                    0xC8B38E74,
                    0xB475F255,
                    0x46FCD9B9,
                    0x7AEB2661,
                    0x8B1DDF84,
                    0x846A0E79,
                    0x915F95E2,
                    0x466E598E,
                    0x20B45770,
                    0x8CD55591,
                    0xC902DE4C,
                    0xB90BACE1,
                    0xBB8205D0,
                    0x11A86248,
                    0x7574A99E,
                    0xB77F19B6,
                    0xE0A9DC09,
                    0x662D09A1,
                    0xC4324633,
                    0xE85A1F02,
                    0x09F0BE8C,
                    0x4A99A025,
                    0x1D6EFE10,
                    0x1AB93D1D,
                    0x0BA5A4DF,
                    0xA186F20F,
                    0x2868F169,
                    0xDCB7DA83,
                    0x573906FE,
                    0xA1E2CE9B,
                    0x4FCD7F52,
                    0x50115E01,
                    0xA70683FA,
                    0xA002B5C4,
                    0x0DE6D027,
                    0x9AF88C27,
                    0x773F8641,
                    0xC3604C06,
                    0x61A806B5,
                    0xF0177A28,
                    0xC0F586E0,
                    0x006058AA,
                    0x30DC7D62,
                    0x11E69ED7,
                    0x2338EA63,
                    0x53C2DD94,
                    0xC2C21634,
                    0xBBCBEE56,
                    0x90BCB6DE,
                    0xEBFC7DA1,
                    0xCE591D76,
                    0x6F05E409,
                    0x4B7C0188,
                    0x39720A3D,
                    0x7C927C24,
                    0x86E3725F,
                    0x724D9DB9,
                    0x1AC15BB4,
                    0xD39EB8FC,
                    0xED545578,
                    0x08FCA5B5,
                    0xD83D7CD3,
                    0x4DAD0FC4,
                    0x1E50EF5E,
                    0xB161E6F8,
                    0xA28514D9,
                    0x6C51133C,
                    0x6FD5C7E7,
                    0x56E14EC4,
                    0x362ABFCE,
                    0xDDC6C837,
                    0xD79A3234,
                    0x92638212,
                    0x670EFA8E,
                    0x406000E0},

            KS3 = {0x3A39CE37,
                    0xD3FAF5CF,
                    0xABC27737,
                    0x5AC52D1B,
                    0x5CB0679E,
                    0x4FA33742,
                    0xD3822740,
                    0x99BC9BBE,
                    0xD5118E9D,
                    0xBF0F7315,
                    0xD62D1C7E,
                    0xC700C47B,
                    0xB78C1B6B,
                    0x21A19045,
                    0xB26EB1BE,
                    0x6A366EB4,
                    0x5748AB2F,
                    0xBC946E79,
                    0xC6A376D2,
                    0x6549C2C8,
                    0x530FF8EE,
                    0x468DDE7D,
                    0xD5730A1D,
                    0x4CD04DC6,
                    0x2939BBDB,
                    0xA9BA4650,
                    0xAC9526E8,
                    0xBE5EE304,
                    0xA1FAD5F0,
                    0x6A2D519A,
                    0x63EF8CE2,
                    0x9A86EE22,
                    0xC089C2B8,
                    0x43242EF6,
                    0xA51E03AA,
                    0x9CF2D0A4,
                    0x83C061BA,
                    0x9BE96A4D,
                    0x8FE51550,
                    0xBA645BD6,
                    0x2826A2F9,
                    0xA73A3AE1,
                    0x4BA99586,
                    0xEF5562E9,
                    0xC72FEFD3,
                    0xF752F7DA,
                    0x3F046F69,
                    0x77FA0A59,
                    0x80E4A915,
                    0x87B08601,
                    0x9B09E6AD,
                    0x3B3EE593,
                    0xE990FD5A,
                    0x9E34D797,
                    0x2CF0B7D9,
                    0x022B8B51,
                    0x96D5AC3A,
                    0x017DA67D,
                    0xD1CF3ED6,
                    0x7C7D2D28,
                    0x1F9F25CF,
                    0xADF2B89B,
                    0x5AD6B472,
                    0x5A88F54C,
                    0xE029AC71,
                    0xE019A5E6,
                    0x47B0ACFD,
                    0xED93FA9B,
                    0xE8D3C48D,
                    0x283B57CC,
                    0xF8D56629,
                    0x79132E28,
                    0x785F0191,
                    0xED756055,
                    0xF7960E44,
                    0xE3D35E8C,
                    0x15056DD4,
                    0x88F46DBA,
                    0x03A16125,
                    0x0564F0BD,
                    0xC3EB9E15,
                    0x3C9057A2,
                    0x97271AEC,
                    0xA93A072A,
                    0x1B3F6D9B,
                    0x1E6321F5,
                    0xF59C66FB,
                    0x26DCF319,
                    0x7533D928,
                    0xB155FDF5,
                    0x03563482,
                    0x8ABA3CBB,
                    0x28517711,
                    0xC20AD9F8,
                    0xABCC5167,
                    0xCCAD925F,
                    0x4DE81751,
                    0x3830DC8E,
                    0x379D5862,
                    0x9320F991,
                    0xEA7A90C2,
                    0xFB3E7BCE,
                    0x5121CE64,
                    0x774FBE32,
                    0xA8B6E37E,
                    0xC3293D46,
                    0x48DE5369,
                    0x6413E680,
                    0xA2AE0810,
                    0xDD6DB224,
                    0x69852DFD,
                    0x09072166,
                    0xB39A460A,
                    0x6445C0DD,
                    0x586CDECF,
                    0x1C20C8AE,
                    0x5BBEF7DD,
                    0x1B588D40,
                    0xCCD2017F,
                    0x6BB4E3BB,
                    0xDDA26A7E,
                    0x3A59FF45,
                    0x3E350A44,
                    0xBCB4CDD5,
                    0x72EACEA8,
                    0xFA6484BB,
                    0x8D6612AE,
                    0xBF3C6F47,
                    0xD29BE463,
                    0x542F5D9E,
                    0xAEC2771B,
                    0xF64E6370,
                    0x740E0D8D,
                    0xE75B1357,
                    0xF8721671,
                    0xAF537D5D,
                    0x4040CB08,
                    0x4EB4E2CC,
                    0x34D2466A,
                    0x0115AF84,
                    0xE1B00428,
                    0x95983A1D,
                    0x06B89FB4,
                    0xCE6EA048,
                    0x6F3F3B82,
                    0x3520AB82,
                    0x011A1D4B,
                    0x277227F8,
                    0x611560B1,
                    0xE7933FDC,
                    0xBB3A792B,
                    0x344525BD,
                    0xA08839E1,
                    0x51CE794B,
                    0x2F32C9B7,
                    0xA01FBAC9,
                    0xE01CC87E,
                    0xBCC7D1F6,
                    0xCF0111C3,
                    0xA1E8AAC7,
                    0x1A908749,
                    0xD44FBD9A,
                    0xD0DADECB,
                    0xD50ADA38,
                    0x0339C32A,
                    0xC6913667,
                    0x8DF9317C,
                    0xE0B12B4F,
                    0xF79E59B7,
                    0x43F5BB3A,
                    0xF2D519FF,
                    0x27D9459C,
                    0xBF97222C,
                    0x15E6FC2A,
                    0x0F91FC71,
                    0x9B941525,
                    0xFAE59361,
                    0xCEB69CEB,
                    0xC2A86459,
                    0x12BAA8D1,
                    0xB6C1075E,
                    0xE3056A0C,
                    0x10D25065,
                    0xCB03A442,
                    0xE0EC6E0E,
                    0x1698DB3B,
                    0x4C98A0BE,
                    0x3278E964,
                    0x9F1F9532,
                    0xE0D392DF,
                    0xD3A0342B,
                    0x8971F21E,
                    0x1B0A7441,
                    0x4BA3348C,
                    0xC5BE7120,
                    0xC37632D8,
                    0xDF359F8D,
                    0x9B992F2E,
                    0xE60B6F47,
                    0x0FE3F11D,
                    0xE54CDA54,
                    0x1EDAD891,
                    0xCE6279CF,
                    0xCD3E7E6F,
                    0x1618B166,
                    0xFD2C1D05,
                    0x848FD2C5,
                    0xF6FB2299,
                    0xF523F357,
                    0xA6327623,
                    0x93A83531,
                    0x56CCCD02,
                    0xACF08162,
                    0x5A75EBB5,
                    0x6E163697,
                    0x88D273CC,
                    0xDE966292,
                    0x81B949D0,
                    0x4C50901B,
                    0x71C65614,
                    0xE6C6C7BD,
                    0x327A140A,
                    0x45E1D006,
                    0xC3F27B9A,
                    0xC9AA53FD,
                    0x62A80F00,
                    0xBB25BFE2,
                    0x35BDD2F6,
                    0x71126905,
                    0xB2040222,
                    0xB6CBCF7C,
                    0xCD769C2B,
                    0x53113EC0,
                    0x1640E3D3,
                    0x38ABBD60,
                    0x2547ADF0,
                    0xBA38209C,
                    0xF746CE76,
                    0x77AFA1C5,
                    0x20756060,
                    0x85CBFE4E,
                    0x8AE88DD8,
                    0x7AAAF9B0,
                    0x4CF9AA7E,
                    0x1948C25C,
                    0x02FB8A8C,
                    0x01C36AE4,
                    0xD6EBE1F9,
                    0x90D4F869,
                    0xA65CDEA0,
                    0x3F09252D,
                    0xC208E69F,
                    0xB74E6132,
                    0xCE77E25B,
                    0x578FDFE3,
                    0x3AC372E6};

    // ====================================
    // Useful constants
    // ====================================

    private static final int ROUNDS = 16;
    private static final int SBOX_SK = 256;
    private static final int SBOX_SK2 = SBOX_SK * 2;
    private static final int SBOX_SK3 = SBOX_SK * 3;
    private static final int P_SZ = ROUNDS + 2;

    private final int[] S; // the s-boxes
    private final int[] P; // the p-array

    public BCrypt() {
        S = new int[SBOX_SK * 4];
        P = new int[P_SZ];
    }

    // ==================================
    // Private Implementation
    // ==================================

    private int F(int x) {
        return (((S[(x >>> 24)] + S[SBOX_SK + ((x >>> 16) & 0xff)])
                ^ S[SBOX_SK2 + ((x >>> 8) & 0xff)]) + S[SBOX_SK3 + (x & 0xff)]);
    }

    /*
     * apply the encryption cycle to each value pair in the table.
     */
    private void processTable(int xl, int xr, int[] table) {
        int size = table.length;

        for (int s = 0; s < size; s += 2) {
            xl ^= P[0];

            for (int i = 1; i < ROUNDS; i += 2) {
                xr ^= F(xl) ^ P[i];
                xl ^= F(xr) ^ P[i + 1];
            }

            xr ^= P[ROUNDS + 1];

            table[s] = xr;
            table[s + 1] = xl; // lgtm [java/index-out-of-bounds]

            xr = xl; // end of cycle swap
            xl = table[s];
        }
    }

    /*
     * Initialize the S-boxes and the P-array, with a fixed string This string contains the
     * hexadecimal digits of pi (3.141...)
     */
    private void initState() {
        System.arraycopy(KS0, 0, S, 0, SBOX_SK);
        System.arraycopy(KS1, 0, S, SBOX_SK, SBOX_SK);
        System.arraycopy(KS2, 0, S, SBOX_SK2, SBOX_SK);
        System.arraycopy(KS3, 0, S, SBOX_SK3, SBOX_SK);

        System.arraycopy(KP, 0, P, 0, P_SZ);

    }

    /*
     * XOR P with key cyclic. This is the first part of ExpandKey function
     */
    private final void cyclicXorKey(byte[] key, int keyLength) {
//        int keyLength = key.length;
        int keyIndex = 0;

        for (int i = 0; i < P_SZ; i++) {
            // get the 32 bits of the key, in 4 * 8 bit chunks
            int data = 0x0000000;
            for (int j = 0; j < 4; j++) {
                // create a 32 bit block
                data = (data << 8) | (key[keyIndex++] & 0xff);

                // wrap when we get to the end of the key
                if (keyIndex >= keyLength) {
                    keyIndex = 0;
                }
            }
            // XOR the newly created 32 bit chunk onto the P-array
            P[i] ^= data;
        }
    }

    /*
     * encrypt magic String 64 times in ECB
     */
    private byte[] encryptMagicString() {
        int[] text = {MAGIC_STRING[0],
                MAGIC_STRING[1],
                MAGIC_STRING[2],
                MAGIC_STRING[3],
                MAGIC_STRING[4],
                MAGIC_STRING[5]};
        for (int i = 0; i < 64; i++) {
            for (int j = 0; j < MAGIC_STRING_LENGTH; j += 2) {
                int left = text[j];
                int right = text[j + 1];

                left ^= P[0];
                for (int k = 1; k < ROUNDS; k += 2) {
                    right ^= F(left) ^ P[k];
                    left ^= F(right) ^ P[k + 1];
                }
                right ^= P[ROUNDS + 1];
                // swap values:
                text[j] = right;
                text[j + 1] = left;
            }
        }
        byte[] result = new byte[24]; // holds 192 bit key
        Pack.intToBigEndian(text, result, 0);
        Arrays.fill(text, 0);
        Arrays.fill(P, 0);
        Arrays.fill(S, 0);

        return result;
    }

    /*
     * This is a part of Eksblowfish function
     *
     * @param table: sub-keys or working key
     * 
     * @param salt32Bit: a 16 byte salt as two 32 bit words
     * 
     * @param iv1: value from last proceeded table
     * 
     * @param iv2: value from last proceeded table
     */
    private void processTableWithSalt(int[] table, int[] salt32Bit, int iv1, int iv2) {
        int xl = iv1 ^ salt32Bit[0];
        int xr = iv2 ^ salt32Bit[1];

        int yl;
        int yr;
        int size = table.length;

        for (int s = 0; s < size; s += 4) {
            xl ^= P[0];
            for (int i = 1; i < ROUNDS; i += 2) {
                xr ^= F(xl) ^ P[i];
                xl ^= F(xr) ^ P[i + 1];
            }
            xr ^= P[ROUNDS + 1];

            // suppress LGTM warnings index-out-of-bounds since the loop increments s by 4
            table[s] = xr;
            table[s + 1] = xl; // lgtm [java/index-out-of-bounds]

            yl = salt32Bit[2] ^ xr;
            yr = salt32Bit[3] ^ xl;

            if (s + 2 >= size) // P holds 18 values
            {
                break;
            }

            yl ^= P[0];
            for (int i = 1; i < ROUNDS; i += 2) {
                yr ^= F(yl) ^ P[i];
                yl ^= F(yr) ^ P[i + 1];
            }
            yr ^= P[ROUNDS + 1];

            table[s + 2] = yr; // lgtm [java/index-out-of-bounds]
            table[s + 3] = yl; // lgtm [java/index-out-of-bounds]

            xl = salt32Bit[0] ^ yr;
            xr = salt32Bit[1] ^ yl;
        }
    }

    /**
     * Derives a raw 192 bit Bcrypt key
     *
     * @param cost the cost factor, treated as an exponent of 2
     * @param salt a 16 byte salt
     * @param psw  the password
     * @return a 192 bit key
     */
    private final byte[] deriveRawKey(int cost, byte[] salt, byte[] psw) {
//        if (salt.length != 16) {
//            throw new DataLengthException("Invalid salt size: 16 bytes expected.");
//        }
        if (cost < 4 || cost > 31) {
            throw new IllegalArgumentException("Illegal cost factor: 4 - 31 expected.");
        }

        if (psw.length == 0) {
            psw = new byte[4];
        }

        // state <- InitState()
        initState();

        int[] salt32Bit = new int[4]; // holds 16 byte salt
        Pack.bigEndianToInt(salt, 0, salt32Bit);

        int[] salt32Bit2 = new int[SALT_SIZE_BYTES]; // swapped values
        salt32Bit2[0] = salt32Bit[2];
        salt32Bit2[1] = salt32Bit[3];
        salt32Bit2[2] = salt32Bit[0];
        salt32Bit2[3] = salt32Bit[1];

        // ExpandKey( state, salt, key):
        cyclicXorKey(psw, psw.length);
        processTableWithSalt(P, salt32Bit, 0, 0);
        Arrays.fill(salt32Bit, 0);
        processTableWithSalt(S, salt32Bit2, P[P.length - 2], P[P.length - 1]);
        Arrays.fill(salt32Bit2, 0);

        int rounds = 1 << cost;
        for (int i = 0; i != rounds; i++) // rounds may be negative if cost is 31
        {
            // state <- ExpandKey(state, 0, key);
            cyclicXorKey(psw, psw.length);
            processTable(0, 0, P);
            processTable(P[P_SZ - 2], P[P_SZ - 1], S);

            // state <- ExpandKey(state, 0, salt);
            cyclicXorKey(salt, SALT_SIZE_BYTES);
            processTable(0, 0, P);
            processTable(P[P_SZ - 2], P[P_SZ - 1], S);
        }

        // encrypt magicString 64 times
        return encryptMagicString();
    }

    /**
     * Size of the salt parameter in bytes
     */
    static final int SALT_SIZE_BYTES = 16;

    /**
     * Minimum value of cost parameter, equal to log2(bytes of salt)
     */
    static final int MIN_COST = 4;

    /**
     * Maximum value of cost parameter (31 == 2,147,483,648)
     */
    static final int MAX_COST = 31;

    /**
     * Maximum size of password == max (unrestricted) size of Blowfish key
     */
    // Blowfish spec limits keys to 448bit/56 bytes to ensure all bits of key affect all ciphertext
    // bits, but technically algorithm handles 72 byte keys and most implementations support this.
    static final int MAX_PASSWORD_BYTES = 72;

    /**
     * Calculates the <b>bcrypt</b> hash of an input - note for processing general passwords you
     * want to make sure the password is terminated in a manner similar to what is done by
     * passwordToByteArray().
     * <p>
     * This implements the raw <b>bcrypt</b> function as defined in the bcrypt specification, not
     * the crypt encoded version implemented in OpenBSD.
     * </p>
     *
     * @param pwInput the password bytes (up to 72 bytes) to use for this invocation.
     * @param salt    the 128 bit salt to use for this invocation.
     * @param cost    the bcrypt cost parameter. The cost of the bcrypt function grows as
     *                <code>2^cost</code>. Legal values are 4..31 inclusive.
     * @return the output of the raw bcrypt operation: a 192 bit (24 byte) hash.
     */
    public byte[] generate(byte[] pwInput, byte[] salt, int cost) {
        if (pwInput == null || salt == null) {
            throw new IllegalArgumentException("pwInput and salt are required");
        }
//        if (salt.length != SALT_SIZE_BYTES) {
//            throw new IllegalArgumentException("BCrypt salt must be 128 bits");
//        }
        if (pwInput.length > MAX_PASSWORD_BYTES) {
            throw new IllegalArgumentException("BCrypt password must be <= 72 bytes");
        }
        if (cost < MIN_COST || cost > MAX_COST) {
            throw new IllegalArgumentException("BCrypt cost must be from 4..31");
        }

        return deriveRawKey(cost, salt, pwInput);
    }
}