package com.unionpay.uas.demo.gov.sm4;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;

public class SM4 {
    public static final int SM4_ENCRYPT = 1;

    public static final int SM4_DECRYPT = 0;

    private long GET_ULONG_BE(byte[] b, int i) {
        long n =
            (long)(b[i] & 0xff) << 24 | (long)((b[i + 1] & 0xff) << 16) | (long)((b[i + 2] & 0xff) << 8)
                | (long)(b[i + 3] & 0xff) & 0xffffffffL;
        return n;
    }

    private void PUT_ULONG_BE(long n, byte[] b, int i) {
        b[i] = (byte)(int)(0xFF & n >> 24);
        b[i + 1] = (byte)(int)(0xFF & n >> 16);
        b[i + 2] = (byte)(int)(0xFF & n >> 8);
        b[i + 3] = (byte)(int)(0xFF & n);
    }

    private long SHL(long x, int n) {
        return (x & 0xFFFFFFFF) << n;
    }

    private long ROTL(long x, int n) {
        return SHL(x, n) | x >> (32 - n);
    }

    private void SWAP(long[] sk, int i) {
        long t = sk[i];
        sk[i] = sk[(31 - i)];
        sk[(31 - i)] = t;
    }

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

    public static final int[] FK = {0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc};

    public static final int[] CK = {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};

    private byte sm4Sbox(byte inch) {
        int i = inch & 0xFF;
        byte retVal = SboxTable[i];
        return retVal;
    }

    private long sm4Lt(long ka) {
        long bb = 0L;
        long c = 0L;
        byte[] a = new byte[4];
        byte[] b = new byte[4];
        PUT_ULONG_BE(ka, a, 0);
        b[0] = sm4Sbox(a[0]);
        b[1] = sm4Sbox(a[1]);
        b[2] = sm4Sbox(a[2]);
        b[3] = sm4Sbox(a[3]);
        bb = GET_ULONG_BE(b, 0);
        c = bb ^ ROTL(bb, 2) ^ ROTL(bb, 10) ^ ROTL(bb, 18) ^ ROTL(bb, 24);
        return c;
    }

    private long sm4F(long x0, long x1, long x2, long x3, long rk) {
        return x0 ^ sm4Lt(x1 ^ x2 ^ x3 ^ rk);
    }

    private long sm4CalciRK(long ka) {
        long bb = 0L;
        long rk = 0L;
        byte[] a = new byte[4];
        byte[] b = new byte[4];
        PUT_ULONG_BE(ka, a, 0);
        b[0] = sm4Sbox(a[0]);
        b[1] = sm4Sbox(a[1]);
        b[2] = sm4Sbox(a[2]);
        b[3] = sm4Sbox(a[3]);
        bb = GET_ULONG_BE(b, 0);
        rk = bb ^ ROTL(bb, 13) ^ ROTL(bb, 23);
        return rk;
    }

    private void sm4_setkey(long[] SK, byte[] key) {
        long[] MK = new long[4];
        long[] k = new long[36];
        int i = 0;
        MK[0] = GET_ULONG_BE(key, 0);
        MK[1] = GET_ULONG_BE(key, 4);
        MK[2] = GET_ULONG_BE(key, 8);
        MK[3] = GET_ULONG_BE(key, 12);
        k[0] = MK[0] ^ (long)FK[0];
        k[1] = MK[1] ^ (long)FK[1];
        k[2] = MK[2] ^ (long)FK[2];
        k[3] = MK[3] ^ (long)FK[3];
        for (; i < 32; i++) {
            k[(i + 4)] = (k[i] ^ sm4CalciRK(k[(i + 1)] ^ k[(i + 2)] ^ k[(i + 3)] ^ (long)CK[i]));
            SK[i] = k[(i + 4)];
        }
    }

    private void sm4_one_round(long[] sk, byte[] input, byte[] output) {
        int i = 0;
        long[] ulbuf = new long[36];
        ulbuf[0] = GET_ULONG_BE(input, 0);
        ulbuf[1] = GET_ULONG_BE(input, 4);
        ulbuf[2] = GET_ULONG_BE(input, 8);
        ulbuf[3] = GET_ULONG_BE(input, 12);
        while (i < 32) {
            ulbuf[(i + 4)] = sm4F(ulbuf[i], ulbuf[(i + 1)], ulbuf[(i + 2)], ulbuf[(i + 3)], sk[i]);
            i++;
        }
        PUT_ULONG_BE(ulbuf[35], output, 0);
        PUT_ULONG_BE(ulbuf[34], output, 4);
        PUT_ULONG_BE(ulbuf[33], output, 8);
        PUT_ULONG_BE(ulbuf[32], output, 12);
    }

    private byte[] padding(byte[] input, int mode) {
        if (input == null) {
            return null;
        }

        byte[] ret = (byte[])null;
        if (mode == SM4_ENCRYPT) {
            int p = 16 - input.length % 16;
            ret = new byte[input.length + p];
            System.arraycopy(input, 0, ret, 0, input.length);
            for (int i = 0; i < p; i++) {
                ret[input.length + i] = (byte)p;
            }
        } else {
            int p = input[input.length - 1];
            ret = new byte[input.length - p];
            System.arraycopy(input, 0, ret, 0, input.length - p);
        }
        return ret;
    }

    public void sm4_setkey_enc(SM4_Context ctx, byte[] key) throws Exception {
        if (ctx == null) {
            throw new Exception("ctx is null!");
        }

        if (key == null || key.length != 16) {
            throw new Exception("key error!");
        }

        ctx.mode = SM4_ENCRYPT;
        sm4_setkey(ctx.sk, key);
    }

    public void sm4_setkey_dec(SM4_Context ctx, byte[] key) throws Exception {
        if (ctx == null) {
            throw new Exception("ctx is null!");
        }

        if (key == null || key.length != 16) {
            throw new Exception("key error!");
        }

        int i = 0;
        ctx.mode = SM4_DECRYPT;
        sm4_setkey(ctx.sk, key);
        for (i = 0; i < 16; i++) {
            SWAP(ctx.sk, i);
        }
    }

    public byte[] sm4_crypt_ecb(SM4_Context ctx, byte[] input) throws Exception {
        if (input == null) {
            throw new Exception("input is null!");
        }

        if ((ctx.isPadding) && (ctx.mode == SM4_ENCRYPT)) {
            input = padding(input, SM4_ENCRYPT);
        }

        int length = input.length;
        ByteArrayInputStream bins = new ByteArrayInputStream(input);
        ByteArrayOutputStream bous = new ByteArrayOutputStream();
        for (; length > 0; length -= 16) {
            byte[] in = new byte[16];
            byte[] out = new byte[16];
            bins.read(in);
            sm4_one_round(ctx.sk, in, out);
            bous.write(out);
        }

        byte[] output = bous.toByteArray();
        if (ctx.isPadding && ctx.mode == SM4_DECRYPT) {
            output = padding(output, SM4_DECRYPT);
        }
        bins.close();
        bous.close();
        return output;
    }

    public byte[] sm4_crypt_cbc(SM4_Context ctx, byte[] iv, byte[] input) throws Exception {
        if (iv == null || iv.length != 16) {
            throw new Exception("iv error!");
        }

        if (input == null) {
            throw new Exception("input is null!");
        }

        if (ctx.isPadding && ctx.mode == SM4_ENCRYPT) {
            input = padding(input, SM4_ENCRYPT);
        }

        int i = 0;
        int length = input.length;
        ByteArrayInputStream bins = new ByteArrayInputStream(input);
        ByteArrayOutputStream bous = new ByteArrayOutputStream();
        if (ctx.mode == SM4_ENCRYPT) {
            for (; length > 0; length -= 16) {
                byte[] in = new byte[16];
                byte[] out = new byte[16];
                byte[] out1 = new byte[16];

                bins.read(in);
                for (i = 0; i < 16; i++) {
                    out[i] = ((byte)(in[i] ^ iv[i]));
                }
                sm4_one_round(ctx.sk, out, out1);
                System.arraycopy(out1, 0, iv, 0, 16);
                bous.write(out1);
            }
        } else {
            byte[] temp = new byte[16];
            for (; length > 0; length -= 16) {
                byte[] in = new byte[16];
                byte[] out = new byte[16];
                byte[] out1 = new byte[16];

                bins.read(in);
                System.arraycopy(in, 0, temp, 0, 16);
                sm4_one_round(ctx.sk, in, out);
                for (i = 0; i < 16; i++) {
                    out1[i] = ((byte)(out[i] ^ iv[i]));
                }
                System.arraycopy(temp, 0, iv, 0, 16);
                bous.write(out1);
            }
        }

        byte[] output = bous.toByteArray();
        if (ctx.isPadding && ctx.mode == SM4_DECRYPT) {
            output = padding(output, SM4_DECRYPT);
        }
        bins.close();
        bous.close();
        return output;
    }
}