国密SM4

SM4 无线局域网标准的分组数据算法。对称加密，密钥长度和分组长度均为128位。

分组密码常用得五种模式，这里主要讲SM4的ECB模式：

• EBC-电码本模式
• CBC-密码分组链接模式
• CTR-计算器模式
• CFB-密码反馈模式
• OFB-输出反馈模式

Maven配置：

<dependency>
    <groupId>org.bouncycastle</groupId>
    <artifactId>bcpkix-jdk15on</artifactId>
</dependency>

特别关注

SM4加解密最需要注意，也是最容易出错的地方是填充模式的处理。而且对数据的填充方式是高度自由的。这里介绍两种填充方式。当然也可以不填充，但一般都会要求使用填充。

进行加密得时候会进行填充，在进行解密时会去填充。若填充方式不匹配，解密得数据将会不正确。

填充方式可以为：数据得长度 + 数据 + 填充，还可以为：数据 + 填充位长度 + 填充，且填充可以在转HEX前也可以在转HEX之后，所以说填充是高度自由的。

相关代码

SM4Context代码：

public class SM4Context {
    public int mode;
    public long[] sk;
    public boolean isPadding;
    public SM4Context() {
        this.mode = 1;
        this.isPadding = true;
        this.sk = new long[32];
    }
}

SM4代码：

public class SM4 {
    public static final int SM4_ENCRYPT = 1;
    public static final int SM4_DECRYPT = 0;
    public static final byte[] SBOX_TABLE = {
            (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 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;
    }
    private byte sm4Sbox(byte inch) {
        int i = inch & 0xFF;
        byte retVal = SBOX_TABLE[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;
        if (mode == SM4_ENCRYPT) {
            int inputLength = input.length;
            String paddingPrefix = String.valueOf(inputLength);
            int paddingPrefixLength = 4 - paddingPrefix.length();
            StringBuffer prefixBuffer = new StringBuffer();
            for (int i = 0; i < paddingPrefixLength; i++) {
                prefixBuffer.append("0");
            }
            paddingPrefix = ByteUtils.toHexString(prefixBuffer.append(paddingPrefix).toString().getBytes());

            int paddingLength = 16 - (inputLength + 4) % 16;
            String inputHex = ByteUtils.toHexString(input);
            StringBuffer stringBuffer = new StringBuffer(paddingPrefix);
            stringBuffer.append(inputHex);
            for (int i = 0; i < paddingLength; i++) {
                stringBuffer.append("00");
            }
            ret = ByteUtils.fromHexString(stringBuffer.toString());
        } else {
            String inputHex = ByteUtils.toHexString(input);
            String paddingPrefix = inputHex.substring(0, 8);
            paddingPrefix = new String(ByteUtils.fromHexString(paddingPrefix));
            int dataLength = Integer.valueOf(paddingPrefix);

            String dataHex = inputHex.substring(8, dataLength * 2 + 8);
            ret = ByteUtils.fromHexString(dataHex);
        }
        return ret;
    }

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

        byte[] ret;
        if (mode == SM4_ENCRYPT) {
            String origin = new String(input);
            int inputLength = origin.length();
            String paddingPrefix = String.valueOf(inputLength);
            int paddingPrefixLength = 4 - paddingPrefix.length();
            StringBuffer prefixBuffer = new StringBuffer();
            for (int i = 0; i < paddingPrefixLength; i++) {
                prefixBuffer.append("0");
            }
            paddingPrefix = prefixBuffer.append(paddingPrefix).toString();

            int paddingLength = 16 - (inputLength + 4) % 16;
            StringBuffer stringBuffer = new StringBuffer(paddingPrefix);
            stringBuffer.append(origin);
            for (int i = 0; i < paddingLength; i++) {
                stringBuffer.append("0");
            }
            ret = stringBuffer.toString().getBytes();
        } else {
            String origin = new String(input);
            String paddingPrefix = origin.substring(0, 4);
            int dataLength = Integer.valueOf(paddingPrefix);

            String data = origin.substring(4, dataLength + 4);
            ret = data.getBytes();
        }
        return ret;
    }

    public void sm4_setkey_enc(SM4Context ctx, byte[] key) throws Exception {
        if (ctx == null) {
            throw new Exception("SM4 sm4_setkey_enc SM4Context is null!");
        }
        if (key == null || key.length != 16) {
            throw new Exception("SM4 sm4_setkey_enc key byte array error!");
        }
        ctx.mode = SM4_ENCRYPT;
        sm4_setkey(ctx.sk, key);
    }

    public void sm4_setkey_dec(SM4Context ctx, byte[] key) throws Exception {
        if (ctx == null) {
            throw new Exception("SM4 sm4_setkey_dec SM4Context is null!");
        }
        if (key == null || key.length != 16) {
            throw new Exception("SM4 sm4_setkey_dec key byte array 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(SM4Context ctx, byte[] input) throws Exception {
        if (input == null) {
            throw new Exception("SM4 sm4_crypt_ecb input byte array 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;
    }
}

SM4Utils代码：

public class SM4Utils {
    public static String encryptDataEcb(String plainText, String sm4Key) throws Exception {
        SM4Context ctx = new SM4Context();
        ctx.isPadding = true;
        ctx.mode = SM4.SM4_ENCRYPT;

        SM4 sm4 = new SM4();

        byte[] keyBytes = ByteUtils.fromHexString(sm4Key);
        sm4.sm4_setkey_enc(ctx, keyBytes);
        byte[] encrypted = sm4.sm4_crypt_ecb(ctx, ByteUtils.fromHexString(plainText));
        return ByteUtils.toHexString(encrypted);
    }
    public static String decryptDataEcb(String cipherText, String sm4Key) throws Exception {
        SM4Context ctx = new SM4Context();
        ctx.isPadding = true;
        ctx.mode = SM4.SM4_DECRYPT;

        byte[] keyBytes = ByteUtils.fromHexString(sm4Key);

        SM4 sm4 = new SM4();
        sm4.sm4_setkey_dec(ctx, keyBytes);
        byte[] decrypted = sm4.sm4_crypt_ecb(ctx, Base64.decodeBase64(cipherTextTransform(cipherText)));
        return ByteUtils.toHexString(decrypted);
    }
    private static String cipherTextTransform(String cipherText) throws Exception {
        byte[] encrypted = ByteUtils.fromHexString(cipherText);
        cipherText = Base64.encodeBase64String(encrypted);
        if (StringUtils.isNotBlank(cipherText)) {
            Pattern p = Pattern.compile("\\s*|\t|\r|\n");
            Matcher m = p.matcher(cipherText);
            cipherText = m.replaceAll("");
        }
        return cipherText;
    }
}