/*
Copyright Suzhou Tongji Fintech Research Institute 2017 All Rights Reserved.
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.

sm4 acceration
modified by Jack, 2017 Oct
*/

package sm4

import (
	"crypto/cipher"
	"crypto/rand"
	"crypto/x509"
	"encoding/pem"
	"errors"
	"io/ioutil"
	"os"
	"strconv"
)

const BlockSize = 16

type SM4Key []byte

type KeySizeError int

// Cipher is an instance of SM4 encryption.
type Sm4Cipher struct {
	subkeys []uint32
	block1  []uint32
	block2  []byte
}

// sm4密钥参量
var fk = [4]uint32{
	0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc,
}

// sm4密钥参量
var ck = [32]uint32{
	0x00070e15, 0x1c232a31, 0x383f464d, 0x545b6269,
	0x70777e85, 0x8c939aa1, 0xa8afb6bd, 0xc4cbd2d9,
	0xe0e7eef5, 0xfc030a11, 0x181f262d, 0x343b4249,
	0x50575e65, 0x6c737a81, 0x888f969d, 0xa4abb2b9,
	0xc0c7ced5, 0xdce3eaf1, 0xf8ff060d, 0x141b2229,
	0x30373e45, 0x4c535a61, 0x686f767d, 0x848b9299,
	0xa0a7aeb5, 0xbcc3cad1, 0xd8dfe6ed, 0xf4fb0209,
	0x10171e25, 0x2c333a41, 0x484f565d, 0x646b7279,
}

// sm4密钥参量
var sbox = [256]uint8{
	0xd6, 0x90, 0xe9, 0xfe, 0xcc, 0xe1, 0x3d, 0xb7, 0x16, 0xb6, 0x14, 0xc2, 0x28, 0xfb, 0x2c, 0x05,
	0x2b, 0x67, 0x9a, 0x76, 0x2a, 0xbe, 0x04, 0xc3, 0xaa, 0x44, 0x13, 0x26, 0x49, 0x86, 0x06, 0x99,
	0x9c, 0x42, 0x50, 0xf4, 0x91, 0xef, 0x98, 0x7a, 0x33, 0x54, 0x0b, 0x43, 0xed, 0xcf, 0xac, 0x62,
	0xe4, 0xb3, 0x1c, 0xa9, 0xc9, 0x08, 0xe8, 0x95, 0x80, 0xdf, 0x94, 0xfa, 0x75, 0x8f, 0x3f, 0xa6,
	0x47, 0x07, 0xa7, 0xfc, 0xf3, 0x73, 0x17, 0xba, 0x83, 0x59, 0x3c, 0x19, 0xe6, 0x85, 0x4f, 0xa8,
	0x68, 0x6b, 0x81, 0xb2, 0x71, 0x64, 0xda, 0x8b, 0xf8, 0xeb, 0x0f, 0x4b, 0x70, 0x56, 0x9d, 0x35,
	0x1e, 0x24, 0x0e, 0x5e, 0x63, 0x58, 0xd1, 0xa2, 0x25, 0x22, 0x7c, 0x3b, 0x01, 0x21, 0x78, 0x87,
	0xd4, 0x00, 0x46, 0x57, 0x9f, 0xd3, 0x27, 0x52, 0x4c, 0x36, 0x02, 0xe7, 0xa0, 0xc4, 0xc8, 0x9e,
	0xea, 0xbf, 0x8a, 0xd2, 0x40, 0xc7, 0x38, 0xb5, 0xa3, 0xf7, 0xf2, 0xce, 0xf9, 0x61, 0x15, 0xa1,
	0xe0, 0xae, 0x5d, 0xa4, 0x9b, 0x34, 0x1a, 0x55, 0xad, 0x93, 0x32, 0x30, 0xf5, 0x8c, 0xb1, 0xe3,
	0x1d, 0xf6, 0xe2, 0x2e, 0x82, 0x66, 0xca, 0x60, 0xc0, 0x29, 0x23, 0xab, 0x0d, 0x53, 0x4e, 0x6f,
	0xd5, 0xdb, 0x37, 0x45, 0xde, 0xfd, 0x8e, 0x2f, 0x03, 0xff, 0x6a, 0x72, 0x6d, 0x6c, 0x5b, 0x51,
	0x8d, 0x1b, 0xaf, 0x92, 0xbb, 0xdd, 0xbc, 0x7f, 0x11, 0xd9, 0x5c, 0x41, 0x1f, 0x10, 0x5a, 0xd8,
	0x0a, 0xc1, 0x31, 0x88, 0xa5, 0xcd, 0x7b, 0xbd, 0x2d, 0x74, 0xd0, 0x12, 0xb8, 0xe5, 0xb4, 0xb0,
	0x89, 0x69, 0x97, 0x4a, 0x0c, 0x96, 0x77, 0x7e, 0x65, 0xb9, 0xf1, 0x09, 0xc5, 0x6e, 0xc6, 0x84,
	0x18, 0xf0, 0x7d, 0xec, 0x3a, 0xdc, 0x4d, 0x20, 0x79, 0xee, 0x5f, 0x3e, 0xd7, 0xcb, 0x39, 0x48,
}

var sbox0 = [256]uint32{
	0xd55b5b8e, 0x924242d0, 0xeaa7a74d, 0xfdfbfb06, 0xcf3333fc, 0xe2878765, 0x3df4f4c9, 0xb5dede6b, 0x1658584e, 0xb4dada6e, 0x14505044, 0xc10b0bca, 0x28a0a088, 0xf8efef17, 0x2cb0b09c, 0x05141411,
	0x2bacac87, 0x669d9dfb, 0x986a6af2, 0x77d9d9ae, 0x2aa8a882, 0xbcfafa46, 0x04101014, 0xc00f0fcf, 0xa8aaaa02, 0x45111154, 0x134c4c5f, 0x269898be, 0x4825256d, 0x841a1a9e, 0x0618181e, 0x9b6666fd,
	0x9e7272ec, 0x4309094a, 0x51414110, 0xf7d3d324, 0x934646d5, 0xecbfbf53, 0x9a6262f8, 0x7be9e992, 0x33ccccff, 0x55515104, 0x0b2c2c27, 0x420d0d4f, 0xeeb7b759, 0xcc3f3ff3, 0xaeb2b21c, 0x638989ea,
	0xe7939374, 0xb1cece7f, 0x1c70706c, 0xaba6a60d, 0xca2727ed, 0x08202028, 0xeba3a348, 0x975656c1, 0x82020280, 0xdc7f7fa3, 0x965252c4, 0xf9ebeb12, 0x74d5d5a1, 0x8d3e3eb3, 0x3ffcfcc3, 0xa49a9a3e,
	0x461d1d5b, 0x071c1c1b, 0xa59e9e3b, 0xfff3f30c, 0xf0cfcf3f, 0x72cdcdbf, 0x175c5c4b, 0xb8eaea52, 0x810e0e8f, 0x5865653d, 0x3cf0f0cc, 0x1964647d, 0xe59b9b7e, 0x87161691, 0x4e3d3d73, 0xaaa2a208,
	0x69a1a1c8, 0x6aadadc7, 0x83060685, 0xb0caca7a, 0x70c5c5b5, 0x659191f4, 0xd96b6bb2, 0x892e2ea7, 0xfbe3e318, 0xe8afaf47, 0x0f3c3c33, 0x4a2d2d67, 0x71c1c1b0, 0x5759590e, 0x9f7676e9, 0x35d4d4e1,
	0x1e787866, 0x249090b4, 0x0e383836, 0x5f797926, 0x628d8def, 0x59616138, 0xd2474795, 0xa08a8a2a, 0x259494b1, 0x228888aa, 0x7df1f18c, 0x3bececd7, 0x01040405, 0x218484a5, 0x79e1e198, 0x851e1e9b,
	0xd7535384, 0x00000000, 0x4719195e, 0x565d5d0b, 0x9d7e7ee3, 0xd04f4f9f, 0x279c9cbb, 0x5349491a, 0x4d31317c, 0x36d8d8ee, 0x0208080a, 0xe49f9f7b, 0xa2828220, 0xc71313d4, 0xcb2323e8, 0x9c7a7ae6,
	0xe9abab42, 0xbdfefe43, 0x882a2aa2, 0xd14b4b9a, 0x41010140, 0xc41f1fdb, 0x38e0e0d8, 0xb7d6d661, 0xa18e8e2f, 0xf4dfdf2b, 0xf1cbcb3a, 0xcd3b3bf6, 0xfae7e71d, 0x608585e5, 0x15545441, 0xa3868625,
	0xe3838360, 0xacbaba16, 0x5c757529, 0xa6929234, 0x996e6ef7, 0x34d0d0e4, 0x1a686872, 0x54555501, 0xafb6b619, 0x914e4edf, 0x32c8c8fa, 0x30c0c0f0, 0xf6d7d721, 0x8e3232bc, 0xb3c6c675, 0xe08f8f6f,
	0x1d747469, 0xf5dbdb2e, 0xe18b8b6a, 0x2eb8b896, 0x800a0a8a, 0x679999fe, 0xc92b2be2, 0x618181e0, 0xc30303c0, 0x29a4a48d, 0x238c8caf, 0xa9aeae07, 0x0d343439, 0x524d4d1f, 0x4f393976, 0x6ebdbdd3,
	0xd6575781, 0xd86f6fb7, 0x37dcdceb, 0x44151551, 0xdd7b7ba6, 0xfef7f709, 0x8c3a3ab6, 0x2fbcbc93, 0x030c0c0f, 0xfcffff03, 0x6ba9a9c2, 0x73c9c9ba, 0x6cb5b5d9, 0x6db1b1dc, 0x5a6d6d37, 0x50454515,
	0x8f3636b9, 0x1b6c6c77, 0xadbebe13, 0x904a4ada, 0xb9eeee57, 0xde7777a9, 0xbef2f24c, 0x7efdfd83, 0x11444455, 0xda6767bd, 0x5d71712c, 0x40050545, 0x1f7c7c63, 0x10404050, 0x5b696932, 0xdb6363b8,
	0x0a282822, 0xc20707c5, 0x31c4c4f5, 0x8a2222a8, 0xa7969631, 0xce3737f9, 0x7aeded97, 0xbff6f649, 0x2db4b499, 0x75d1d1a4, 0xd3434390, 0x1248485a, 0xbae2e258, 0xe6979771, 0xb6d2d264, 0xb2c2c270,
	0x8b2626ad, 0x68a5a5cd, 0x955e5ecb, 0x4b292962, 0x0c30303c, 0x945a5ace, 0x76ddddab, 0x7ff9f986, 0x649595f1, 0xbbe6e65d, 0xf2c7c735, 0x0924242d, 0xc61717d1, 0x6fb9b9d6, 0xc51b1bde, 0x86121294,
	0x18606078, 0xf3c3c330, 0x7cf5f589, 0xefb3b35c, 0x3ae8e8d2, 0xdf7373ac, 0x4c353579, 0x208080a0, 0x78e5e59d, 0xedbbbb56, 0x5e7d7d23, 0x3ef8f8c6, 0xd45f5f8b, 0xc82f2fe7, 0x39e4e4dd, 0x49212168,
}

var sbox1 = [256]uint32{
	0x5b5b8ed5, 0x4242d092, 0xa7a74dea, 0xfbfb06fd, 0x3333fccf, 0x878765e2, 0xf4f4c93d, 0xdede6bb5, 0x58584e16, 0xdada6eb4, 0x50504414, 0x0b0bcac1, 0xa0a08828, 0xefef17f8, 0xb0b09c2c, 0x14141105,
	0xacac872b, 0x9d9dfb66, 0x6a6af298, 0xd9d9ae77, 0xa8a8822a, 0xfafa46bc, 0x10101404, 0x0f0fcfc0, 0xaaaa02a8, 0x11115445, 0x4c4c5f13, 0x9898be26, 0x25256d48, 0x1a1a9e84, 0x18181e06, 0x6666fd9b,
	0x7272ec9e, 0x09094a43, 0x41411051, 0xd3d324f7, 0x4646d593, 0xbfbf53ec, 0x6262f89a, 0xe9e9927b, 0xccccff33, 0x51510455, 0x2c2c270b, 0x0d0d4f42, 0xb7b759ee, 0x3f3ff3cc, 0xb2b21cae, 0x8989ea63,
	0x939374e7, 0xcece7fb1, 0x70706c1c, 0xa6a60dab, 0x2727edca, 0x20202808, 0xa3a348eb, 0x5656c197, 0x02028082, 0x7f7fa3dc, 0x5252c496, 0xebeb12f9, 0xd5d5a174, 0x3e3eb38d, 0xfcfcc33f, 0x9a9a3ea4,
	0x1d1d5b46, 0x1c1c1b07, 0x9e9e3ba5, 0xf3f30cff, 0xcfcf3ff0, 0xcdcdbf72, 0x5c5c4b17, 0xeaea52b8, 0x0e0e8f81, 0x65653d58, 0xf0f0cc3c, 0x64647d19, 0x9b9b7ee5, 0x16169187, 0x3d3d734e, 0xa2a208aa,
	0xa1a1c869, 0xadadc76a, 0x06068583, 0xcaca7ab0, 0xc5c5b570, 0x9191f465, 0x6b6bb2d9, 0x2e2ea789, 0xe3e318fb, 0xafaf47e8, 0x3c3c330f, 0x2d2d674a, 0xc1c1b071, 0x59590e57, 0x7676e99f, 0xd4d4e135,
	0x7878661e, 0x9090b424, 0x3838360e, 0x7979265f, 0x8d8def62, 0x61613859, 0x474795d2, 0x8a8a2aa0, 0x9494b125, 0x8888aa22, 0xf1f18c7d, 0xececd73b, 0x04040501, 0x8484a521, 0xe1e19879, 0x1e1e9b85,
	0x535384d7, 0x00000000, 0x19195e47, 0x5d5d0b56, 0x7e7ee39d, 0x4f4f9fd0, 0x9c9cbb27, 0x49491a53, 0x31317c4d, 0xd8d8ee36, 0x08080a02, 0x9f9f7be4, 0x828220a2, 0x1313d4c7, 0x2323e8cb, 0x7a7ae69c,
	0xabab42e9, 0xfefe43bd, 0x2a2aa288, 0x4b4b9ad1, 0x01014041, 0x1f1fdbc4, 0xe0e0d838, 0xd6d661b7, 0x8e8e2fa1, 0xdfdf2bf4, 0xcbcb3af1, 0x3b3bf6cd, 0xe7e71dfa, 0x8585e560, 0x54544115, 0x868625a3,
	0x838360e3, 0xbaba16ac, 0x7575295c, 0x929234a6, 0x6e6ef799, 0xd0d0e434, 0x6868721a, 0x55550154, 0xb6b619af, 0x4e4edf91, 0xc8c8fa32, 0xc0c0f030, 0xd7d721f6, 0x3232bc8e, 0xc6c675b3, 0x8f8f6fe0,
	0x7474691d, 0xdbdb2ef5, 0x8b8b6ae1, 0xb8b8962e, 0x0a0a8a80, 0x9999fe67, 0x2b2be2c9, 0x8181e061, 0x0303c0c3, 0xa4a48d29, 0x8c8caf23, 0xaeae07a9, 0x3434390d, 0x4d4d1f52, 0x3939764f, 0xbdbdd36e,
	0x575781d6, 0x6f6fb7d8, 0xdcdceb37, 0x15155144, 0x7b7ba6dd, 0xf7f709fe, 0x3a3ab68c, 0xbcbc932f, 0x0c0c0f03, 0xffff03fc, 0xa9a9c26b, 0xc9c9ba73, 0xb5b5d96c, 0xb1b1dc6d, 0x6d6d375a, 0x45451550,
	0x3636b98f, 0x6c6c771b, 0xbebe13ad, 0x4a4ada90, 0xeeee57b9, 0x7777a9de, 0xf2f24cbe, 0xfdfd837e, 0x44445511, 0x6767bdda, 0x71712c5d, 0x05054540, 0x7c7c631f, 0x40405010, 0x6969325b, 0x6363b8db,
	0x2828220a, 0x0707c5c2, 0xc4c4f531, 0x2222a88a, 0x969631a7, 0x3737f9ce, 0xeded977a, 0xf6f649bf, 0xb4b4992d, 0xd1d1a475, 0x434390d3, 0x48485a12, 0xe2e258ba, 0x979771e6, 0xd2d264b6, 0xc2c270b2,
	0x2626ad8b, 0xa5a5cd68, 0x5e5ecb95, 0x2929624b, 0x30303c0c, 0x5a5ace94, 0xddddab76, 0xf9f9867f, 0x9595f164, 0xe6e65dbb, 0xc7c735f2, 0x24242d09, 0x1717d1c6, 0xb9b9d66f, 0x1b1bdec5, 0x12129486,
	0x60607818, 0xc3c330f3, 0xf5f5897c, 0xb3b35cef, 0xe8e8d23a, 0x7373acdf, 0x3535794c, 0x8080a020, 0xe5e59d78, 0xbbbb56ed, 0x7d7d235e, 0xf8f8c63e, 0x5f5f8bd4, 0x2f2fe7c8, 0xe4e4dd39, 0x21216849,
}

var sbox2 = [256]uint32{
	0x5b8ed55b, 0x42d09242, 0xa74deaa7, 0xfb06fdfb, 0x33fccf33, 0x8765e287, 0xf4c93df4, 0xde6bb5de, 0x584e1658, 0xda6eb4da, 0x50441450, 0x0bcac10b, 0xa08828a0, 0xef17f8ef, 0xb09c2cb0, 0x14110514,
	0xac872bac, 0x9dfb669d, 0x6af2986a, 0xd9ae77d9, 0xa8822aa8, 0xfa46bcfa, 0x10140410, 0x0fcfc00f, 0xaa02a8aa, 0x11544511, 0x4c5f134c, 0x98be2698, 0x256d4825, 0x1a9e841a, 0x181e0618, 0x66fd9b66,
	0x72ec9e72, 0x094a4309, 0x41105141, 0xd324f7d3, 0x46d59346, 0xbf53ecbf, 0x62f89a62, 0xe9927be9, 0xccff33cc, 0x51045551, 0x2c270b2c, 0x0d4f420d, 0xb759eeb7, 0x3ff3cc3f, 0xb21caeb2, 0x89ea6389,
	0x9374e793, 0xce7fb1ce, 0x706c1c70, 0xa60daba6, 0x27edca27, 0x20280820, 0xa348eba3, 0x56c19756, 0x02808202, 0x7fa3dc7f, 0x52c49652, 0xeb12f9eb, 0xd5a174d5, 0x3eb38d3e, 0xfcc33ffc, 0x9a3ea49a,
	0x1d5b461d, 0x1c1b071c, 0x9e3ba59e, 0xf30cfff3, 0xcf3ff0cf, 0xcdbf72cd, 0x5c4b175c, 0xea52b8ea, 0x0e8f810e, 0x653d5865, 0xf0cc3cf0, 0x647d1964, 0x9b7ee59b, 0x16918716, 0x3d734e3d, 0xa208aaa2,
	0xa1c869a1, 0xadc76aad, 0x06858306, 0xca7ab0ca, 0xc5b570c5, 0x91f46591, 0x6bb2d96b, 0x2ea7892e, 0xe318fbe3, 0xaf47e8af, 0x3c330f3c, 0x2d674a2d, 0xc1b071c1, 0x590e5759, 0x76e99f76, 0xd4e135d4,
	0x78661e78, 0x90b42490, 0x38360e38, 0x79265f79, 0x8def628d, 0x61385961, 0x4795d247, 0x8a2aa08a, 0x94b12594, 0x88aa2288, 0xf18c7df1, 0xecd73bec, 0x04050104, 0x84a52184, 0xe19879e1, 0x1e9b851e,
	0x5384d753, 0x00000000, 0x195e4719, 0x5d0b565d, 0x7ee39d7e, 0x4f9fd04f, 0x9cbb279c, 0x491a5349, 0x317c4d31, 0xd8ee36d8, 0x080a0208, 0x9f7be49f, 0x8220a282, 0x13d4c713, 0x23e8cb23, 0x7ae69c7a,
	0xab42e9ab, 0xfe43bdfe, 0x2aa2882a, 0x4b9ad14b, 0x01404101, 0x1fdbc41f, 0xe0d838e0, 0xd661b7d6, 0x8e2fa18e, 0xdf2bf4df, 0xcb3af1cb, 0x3bf6cd3b, 0xe71dfae7, 0x85e56085, 0x54411554, 0x8625a386,
	0x8360e383, 0xba16acba, 0x75295c75, 0x9234a692, 0x6ef7996e, 0xd0e434d0, 0x68721a68, 0x55015455, 0xb619afb6, 0x4edf914e, 0xc8fa32c8, 0xc0f030c0, 0xd721f6d7, 0x32bc8e32, 0xc675b3c6, 0x8f6fe08f,
	0x74691d74, 0xdb2ef5db, 0x8b6ae18b, 0xb8962eb8, 0x0a8a800a, 0x99fe6799, 0x2be2c92b, 0x81e06181, 0x03c0c303, 0xa48d29a4, 0x8caf238c, 0xae07a9ae, 0x34390d34, 0x4d1f524d, 0x39764f39, 0xbdd36ebd,
	0x5781d657, 0x6fb7d86f, 0xdceb37dc, 0x15514415, 0x7ba6dd7b, 0xf709fef7, 0x3ab68c3a, 0xbc932fbc, 0x0c0f030c, 0xff03fcff, 0xa9c26ba9, 0xc9ba73c9, 0xb5d96cb5, 0xb1dc6db1, 0x6d375a6d, 0x45155045,
	0x36b98f36, 0x6c771b6c, 0xbe13adbe, 0x4ada904a, 0xee57b9ee, 0x77a9de77, 0xf24cbef2, 0xfd837efd, 0x44551144, 0x67bdda67, 0x712c5d71, 0x05454005, 0x7c631f7c, 0x40501040, 0x69325b69, 0x63b8db63,
	0x28220a28, 0x07c5c207, 0xc4f531c4, 0x22a88a22, 0x9631a796, 0x37f9ce37, 0xed977aed, 0xf649bff6, 0xb4992db4, 0xd1a475d1, 0x4390d343, 0x485a1248, 0xe258bae2, 0x9771e697, 0xd264b6d2, 0xc270b2c2,
	0x26ad8b26, 0xa5cd68a5, 0x5ecb955e, 0x29624b29, 0x303c0c30, 0x5ace945a, 0xddab76dd, 0xf9867ff9, 0x95f16495, 0xe65dbbe6, 0xc735f2c7, 0x242d0924, 0x17d1c617, 0xb9d66fb9, 0x1bdec51b, 0x12948612,
	0x60781860, 0xc330f3c3, 0xf5897cf5, 0xb35cefb3, 0xe8d23ae8, 0x73acdf73, 0x35794c35, 0x80a02080, 0xe59d78e5, 0xbb56edbb, 0x7d235e7d, 0xf8c63ef8, 0x5f8bd45f, 0x2fe7c82f, 0xe4dd39e4, 0x21684921,
}

var sbox3 = [256]uint32{
	0x8ed55b5b, 0xd0924242, 0x4deaa7a7, 0x06fdfbfb, 0xfccf3333, 0x65e28787, 0xc93df4f4, 0x6bb5dede, 0x4e165858, 0x6eb4dada, 0x44145050, 0xcac10b0b, 0x8828a0a0, 0x17f8efef, 0x9c2cb0b0, 0x11051414,
	0x872bacac, 0xfb669d9d, 0xf2986a6a, 0xae77d9d9, 0x822aa8a8, 0x46bcfafa, 0x14041010, 0xcfc00f0f, 0x02a8aaaa, 0x54451111, 0x5f134c4c, 0xbe269898, 0x6d482525, 0x9e841a1a, 0x1e061818, 0xfd9b6666,
	0xec9e7272, 0x4a430909, 0x10514141, 0x24f7d3d3, 0xd5934646, 0x53ecbfbf, 0xf89a6262, 0x927be9e9, 0xff33cccc, 0x04555151, 0x270b2c2c, 0x4f420d0d, 0x59eeb7b7, 0xf3cc3f3f, 0x1caeb2b2, 0xea638989,
	0x74e79393, 0x7fb1cece, 0x6c1c7070, 0x0daba6a6, 0xedca2727, 0x28082020, 0x48eba3a3, 0xc1975656, 0x80820202, 0xa3dc7f7f, 0xc4965252, 0x12f9ebeb, 0xa174d5d5, 0xb38d3e3e, 0xc33ffcfc, 0x3ea49a9a,
	0x5b461d1d, 0x1b071c1c, 0x3ba59e9e, 0x0cfff3f3, 0x3ff0cfcf, 0xbf72cdcd, 0x4b175c5c, 0x52b8eaea, 0x8f810e0e, 0x3d586565, 0xcc3cf0f0, 0x7d196464, 0x7ee59b9b, 0x91871616, 0x734e3d3d, 0x08aaa2a2,
	0xc869a1a1, 0xc76aadad, 0x85830606, 0x7ab0caca, 0xb570c5c5, 0xf4659191, 0xb2d96b6b, 0xa7892e2e, 0x18fbe3e3, 0x47e8afaf, 0x330f3c3c, 0x674a2d2d, 0xb071c1c1, 0x0e575959, 0xe99f7676, 0xe135d4d4,
	0x661e7878, 0xb4249090, 0x360e3838, 0x265f7979, 0xef628d8d, 0x38596161, 0x95d24747, 0x2aa08a8a, 0xb1259494, 0xaa228888, 0x8c7df1f1, 0xd73becec, 0x05010404, 0xa5218484, 0x9879e1e1, 0x9b851e1e,
	0x84d75353, 0x00000000, 0x5e471919, 0x0b565d5d, 0xe39d7e7e, 0x9fd04f4f, 0xbb279c9c, 0x1a534949, 0x7c4d3131, 0xee36d8d8, 0x0a020808, 0x7be49f9f, 0x20a28282, 0xd4c71313, 0xe8cb2323, 0xe69c7a7a,
	0x42e9abab, 0x43bdfefe, 0xa2882a2a, 0x9ad14b4b, 0x40410101, 0xdbc41f1f, 0xd838e0e0, 0x61b7d6d6, 0x2fa18e8e, 0x2bf4dfdf, 0x3af1cbcb, 0xf6cd3b3b, 0x1dfae7e7, 0xe5608585, 0x41155454, 0x25a38686,
	0x60e38383, 0x16acbaba, 0x295c7575, 0x34a69292, 0xf7996e6e, 0xe434d0d0, 0x721a6868, 0x01545555, 0x19afb6b6, 0xdf914e4e, 0xfa32c8c8, 0xf030c0c0, 0x21f6d7d7, 0xbc8e3232, 0x75b3c6c6, 0x6fe08f8f,
	0x691d7474, 0x2ef5dbdb, 0x6ae18b8b, 0x962eb8b8, 0x8a800a0a, 0xfe679999, 0xe2c92b2b, 0xe0618181, 0xc0c30303, 0x8d29a4a4, 0xaf238c8c, 0x07a9aeae, 0x390d3434, 0x1f524d4d, 0x764f3939, 0xd36ebdbd,
	0x81d65757, 0xb7d86f6f, 0xeb37dcdc, 0x51441515, 0xa6dd7b7b, 0x09fef7f7, 0xb68c3a3a, 0x932fbcbc, 0x0f030c0c, 0x03fcffff, 0xc26ba9a9, 0xba73c9c9, 0xd96cb5b5, 0xdc6db1b1, 0x375a6d6d, 0x15504545,
	0xb98f3636, 0x771b6c6c, 0x13adbebe, 0xda904a4a, 0x57b9eeee, 0xa9de7777, 0x4cbef2f2, 0x837efdfd, 0x55114444, 0xbdda6767, 0x2c5d7171, 0x45400505, 0x631f7c7c, 0x50104040, 0x325b6969, 0xb8db6363,
	0x220a2828, 0xc5c20707, 0xf531c4c4, 0xa88a2222, 0x31a79696, 0xf9ce3737, 0x977aeded, 0x49bff6f6, 0x992db4b4, 0xa475d1d1, 0x90d34343, 0x5a124848, 0x58bae2e2, 0x71e69797, 0x64b6d2d2, 0x70b2c2c2,
	0xad8b2626, 0xcd68a5a5, 0xcb955e5e, 0x624b2929, 0x3c0c3030, 0xce945a5a, 0xab76dddd, 0x867ff9f9, 0xf1649595, 0x5dbbe6e6, 0x35f2c7c7, 0x2d092424, 0xd1c61717, 0xd66fb9b9, 0xdec51b1b, 0x94861212,
	0x78186060, 0x30f3c3c3, 0x897cf5f5, 0x5cefb3b3, 0xd23ae8e8, 0xacdf7373, 0x794c3535, 0xa0208080, 0x9d78e5e5, 0x56edbbbb, 0x235e7d7d, 0xc63ef8f8, 0x8bd45f5f, 0xe7c82f2f, 0xdd39e4e4, 0x68492121,
}

func rl(x uint32, i uint8) uint32 { return (x << (i % 32)) | (x >> (32 - (i % 32))) }

func l0(b uint32) uint32 { return b ^ rl(b, 13) ^ rl(b, 23) }

func feistel0(x0, x1, x2, x3, rk uint32) uint32 { return x0 ^ l0(p(x1^x2^x3^rk)) }

//非线性变换τ(.)
func p(a uint32) uint32 {
	return (uint32(sbox[a>>24]) << 24) ^ (uint32(sbox[(a>>16)&0xff]) << 16) ^ (uint32(sbox[(a>>8)&0xff]) << 8) ^ uint32(sbox[(a)&0xff])
}

func permuteInitialBlock(b []uint32, block []byte) {
	for i := 0; i < 4; i++ {
		b[i] = (uint32(block[i*4]) << 24) | (uint32(block[i*4+1]) << 16) |
			(uint32(block[i*4+2]) << 8) | (uint32(block[i*4+3]))
	}
}

func permuteFinalBlock(b []byte, block []uint32) {
	for i := 0; i < 4; i++ {
		b[i*4] = uint8(block[i] >> 24)
		b[i*4+1] = uint8(block[i] >> 16)
		b[i*4+2] = uint8(block[i] >> 8)
		b[i*4+3] = uint8(block[i])
	}
}

//修改后的加密核心函数
func cryptBlock(subkeys []uint32, b []uint32, r []byte, dst, src []byte, decrypt bool) {
	permuteInitialBlock(b, src)

	// bounds check elimination in major encryption loop
	// https://go101.org/article/bounds-check-elimination.html
	_ = b[3]
	if decrypt {
		for i := 0; i < 8; i++ {
			s := subkeys[31-4*i-3 : 31-4*i-3+4]
			x := b[1] ^ b[2] ^ b[3] ^ s[3]
			b[0] = b[0] ^ sbox0[x&0xff] ^ sbox1[(x>>8)&0xff] ^ sbox2[(x>>16)&0xff] ^ sbox3[(x>>24)&0xff]
			x = b[0] ^ b[2] ^ b[3] ^ s[2]
			b[1] = b[1] ^ sbox0[x&0xff] ^ sbox1[(x>>8)&0xff] ^ sbox2[(x>>16)&0xff] ^ sbox3[(x>>24)&0xff]
			x = b[0] ^ b[1] ^ b[3] ^ s[1]
			b[2] = b[2] ^ sbox0[x&0xff] ^ sbox1[(x>>8)&0xff] ^ sbox2[(x>>16)&0xff] ^ sbox3[(x>>24)&0xff]
			x = b[1] ^ b[2] ^ b[0] ^ s[0]
			b[3] = b[3] ^ sbox0[x&0xff] ^ sbox1[(x>>8)&0xff] ^ sbox2[(x>>16)&0xff] ^ sbox3[(x>>24)&0xff]
		}
	} else {
		for i := 0; i < 8; i++ {
			s := subkeys[4*i : 4*i+4]
			x := b[1] ^ b[2] ^ b[3] ^ s[0]
			b[0] = b[0] ^ sbox0[x&0xff] ^ sbox1[(x>>8)&0xff] ^ sbox2[(x>>16)&0xff] ^ sbox3[(x>>24)&0xff]
			x = b[0] ^ b[2] ^ b[3] ^ s[1]
			b[1] = b[1] ^ sbox0[x&0xff] ^ sbox1[(x>>8)&0xff] ^ sbox2[(x>>16)&0xff] ^ sbox3[(x>>24)&0xff]
			x = b[0] ^ b[1] ^ b[3] ^ s[2]
			b[2] = b[2] ^ sbox0[x&0xff] ^ sbox1[(x>>8)&0xff] ^ sbox2[(x>>16)&0xff] ^ sbox3[(x>>24)&0xff]
			x = b[1] ^ b[2] ^ b[0] ^ s[3]
			b[3] = b[3] ^ sbox0[x&0xff] ^ sbox1[(x>>8)&0xff] ^ sbox2[(x>>16)&0xff] ^ sbox3[(x>>24)&0xff]
		}
	}
	b[0], b[1], b[2], b[3] = b[3], b[2], b[1], b[0]
	permuteFinalBlock(r, b)
	copy(dst, r)
}

func generateSubKeys(key []byte) []uint32 {
	subkeys := make([]uint32, 32)
	b := make([]uint32, 4)
	permuteInitialBlock(b, key)
	b[0] ^= fk[0]
	b[1] ^= fk[1]
	b[2] ^= fk[2]
	b[3] ^= fk[3]
	for i := 0; i < 32; i++ {
		subkeys[i] = feistel0(b[0], b[1], b[2], b[3], ck[i])
		b[0], b[1], b[2], b[3] = b[1], b[2], b[3], subkeys[i]
	}
	return subkeys
}

func EncryptBlock(key SM4Key, dst, src []byte) {
	subkeys := generateSubKeys(key)
	cryptBlock(subkeys, make([]uint32, 4), make([]byte, 16), dst, src, false)
}

func DecryptBlock(key SM4Key, dst, src []byte) {
	subkeys := generateSubKeys(key)
	cryptBlock(subkeys, make([]uint32, 4), make([]byte, 16), dst, src, true)
}

func ReadKeyFromMem(data []byte, pwd []byte) (SM4Key, error) {
	block, _ := pem.Decode(data)
	if x509.IsEncryptedPEMBlock(block) {
		if block.Type != "SM4 ENCRYPTED KEY" {
			return nil, errors.New("SM4: unknown type")
		}
		if pwd == nil {
			return nil, errors.New("SM4: need passwd")
		}
		data, err := x509.DecryptPEMBlock(block, pwd)
		if err != nil {
			return nil, err
		}
		return data, nil
	}
	if block.Type != "SM4 KEY" {
		return nil, errors.New("SM4: unknown type")
	}
	return block.Bytes, nil
}

func ReadKeyFromPem(FileName string, pwd []byte) (SM4Key, error) {
	data, err := ioutil.ReadFile(FileName)
	if err != nil {
		return nil, err
	}
	return ReadKeyFromMem(data, pwd)
}

func WriteKeytoMem(key SM4Key, pwd []byte) ([]byte, error) {
	if pwd != nil {
		block, err := x509.EncryptPEMBlock(rand.Reader,
			"SM4 ENCRYPTED KEY", key, pwd, x509.PEMCipherAES256)
		if err != nil {
			return nil, err
		}
		return pem.EncodeToMemory(block), nil
	} else {
		block := &pem.Block{
			Type:  "SM4 KEY",
			Bytes: key,
		}
		return pem.EncodeToMemory(block), nil
	}
}

func WriteKeyToPem(FileName string, key SM4Key, pwd []byte) (bool, error) {
	var block *pem.Block

	if pwd != nil {
		var err error
		block, err = x509.EncryptPEMBlock(rand.Reader,
			"SM4 ENCRYPTED KEY", key, pwd, x509.PEMCipherAES256)
		if err != nil {
			return false, err
		}
	} else {
		block = &pem.Block{
			Type:  "SM4 KEY",
			Bytes: key,
		}
	}
	file, err := os.Create(FileName)
	if err != nil {
		return false, err
	}
	defer file.Close()
	err = pem.Encode(file, block)
	if err != nil {
		return false, nil
	}
	return true, nil
}

func (k KeySizeError) Error() string {
	return "SM4: invalid key size " + strconv.Itoa(int(k))
}

// NewCipher creates and returns a new cipher.Block.
func NewCipher(key []byte) (cipher.Block, error) {
	if len(key) != BlockSize {
		return nil, KeySizeError(len(key))
	}
	c := new(Sm4Cipher)
	c.subkeys = generateSubKeys(key)
	c.block1 = make([]uint32, 4)
	c.block2 = make([]byte, 16)
	return c, nil
}

func (c *Sm4Cipher) BlockSize() int {
	return BlockSize
}

func (c *Sm4Cipher) Encrypt(dst, src []byte) {
	cryptBlock(c.subkeys, c.block1, c.block2, dst, src, false)
}

func (c *Sm4Cipher) Decrypt(dst, src []byte) {
	cryptBlock(c.subkeys, c.block1, c.block2, dst, src, true)
}