Android 实现SM4加解密

该博客主要讲述在Android和Java环境下实现SMS4加解密算法。因传入格式等差异,对原博客项目中SM4调用部分进行了修改,还涉及sm4算法内核及Android调用封装。

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参考:Android\java实现SMS4加解密算法

因与传入格式等的不同,修改了原博客项目对SM4调用部分。

sm4算法内核

package com.wqk.teststring;

import java.util.Arrays;

public class SM4 {

    private static SM4 mSm4 = null;

    public static SM4 getInstance() {
        if (mSm4 == null) {
            mSm4 = new SM4();
        }
        return mSm4;
    }


    public static final int DECRYPT = 0; // 解密
    public static final int ENCRYPT = 1; // 加密
    public static final int ROUND = 32;
    private static final int BLOCK = 16;

    private byte[] Sbox = { (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 };

    private 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 int Rotl(int x, int y) {
        return x << y | x >>> (32 - y);
    }

    private int ByteSub(int A) {
        return (Sbox[A >>> 24 & 0xFF] & 0xFF) << 24
                | (Sbox[A >>> 16 & 0xFF] & 0xFF) << 16
                | (Sbox[A >>> 8 & 0xFF] & 0xFF) << 8 | (Sbox[A & 0xFF] & 0xFF);
    }

    private int L1(int B) {
        return B ^ Rotl(B, 2) ^ Rotl(B, 10) ^ Rotl(B, 18) ^ Rotl(B, 24);
        // return B^(B<<2|B>>>30)^(B<<10|B>>>22)^(B<<18|B>>>14)^(B<<24|B>>>8);
    }

    private int L2(int B) {
        return B ^ Rotl(B, 13) ^ Rotl(B, 23);
        // return B^(B<<13|B>>>19)^(B<<23|B>>>9);
    }

    void SMS4Crypt(byte[] Input, byte[] Output, int[] rk) {
        int r, mid;
        int[] x = new int[4];
        int[] tmp = new int[4];
        for (int i = 0; i < 4; i++) {
            tmp[0] = Input[0 + 4 * i] & 0xff;
            tmp[1] = Input[1 + 4 * i] & 0xff;
            tmp[2] = Input[2 + 4 * i] & 0xff;
            tmp[3] = Input[3 + 4 * i] & 0xff;
            x[i] = tmp[0] << 24 | tmp[1] << 16 | tmp[2] << 8 | tmp[3];
            // x[i]=(Input[0+4*i]<<24|Input[1+4*i]<<16|Input[2+4*i]<<8|Input[3+4*i]);
        }
        for (r = 0; r < 32; r += 4) {
            mid = x[1] ^ x[2] ^ x[3] ^ rk[r + 0];
            mid = ByteSub(mid);
            x[0] = x[0] ^ L1(mid); // x4

            mid = x[2] ^ x[3] ^ x[0] ^ rk[r + 1];
            mid = ByteSub(mid);
            x[1] = x[1] ^ L1(mid); // x5

            mid = x[3] ^ x[0] ^ x[1] ^ rk[r + 2];
            mid = ByteSub(mid);
            x[2] = x[2] ^ L1(mid); // x6

            mid = x[0] ^ x[1] ^ x[2] ^ rk[r + 3];
            mid = ByteSub(mid);
            x[3] = x[3] ^ L1(mid); // x7
        }

        // Reverse
        for (int j = 0; j < 16; j += 4) {
            Output[j] = (byte) (x[3 - j / 4] >>> 24 & 0xFF);
            Output[j + 1] = (byte) (x[3 - j / 4] >>> 16 & 0xFF);
            Output[j + 2] = (byte) (x[3 - j / 4] >>> 8 & 0xFF);
            Output[j + 3] = (byte) (x[3 - j / 4] & 0xFF);
        }
    }

    private void SMS4KeyExt(byte[] Key, int[] rk, int CryptFlag) {
        int r, mid;
        int[] x = new int[4];
        int[] tmp = new int[4];
        for (int i = 0; i < 4; i++) {
            tmp[0] = Key[0 + 4 * i] & 0xFF;
            tmp[1] = Key[1 + 4 * i] & 0xff;
            tmp[2] = Key[2 + 4 * i] & 0xff;
            tmp[3] = Key[3 + 4 * i] & 0xff;
            x[i] = tmp[0] << 24 | tmp[1] << 16 | tmp[2] << 8 | tmp[3];
        }
        x[0] ^= 0xa3b1bac6;
        x[1] ^= 0x56aa3350;
        x[2] ^= 0x677d9197;
        x[3] ^= 0xb27022dc;
        for (r = 0; r < 32; r += 4) {
            mid = x[1] ^ x[2] ^ x[3] ^ CK[r + 0];
            mid = ByteSub(mid);
            rk[r + 0] = x[0] ^= L2(mid); // rk0=K4

            mid = x[2] ^ x[3] ^ x[0] ^ CK[r + 1];
            mid = ByteSub(mid);
            rk[r + 1] = x[1] ^= L2(mid); // rk1=K5

            mid = x[3] ^ x[0] ^ x[1] ^ CK[r + 2];
            mid = ByteSub(mid);
            rk[r + 2] = x[2] ^= L2(mid); // rk2=K6

            mid = x[0] ^ x[1] ^ x[2] ^ CK[r + 3];
            mid = ByteSub(mid);
            rk[r + 3] = x[3] ^= L2(mid); // rk3=K7
        }

        // 解密时轮密钥使用顺序:rk31,rk30,...,rk0 //解密时轮密钥反向
        if (CryptFlag == DECRYPT) {
            for (r = 0; r < 16; r++) {
                mid = rk[r];
                rk[r] = rk[31 - r];
                rk[31 - r] = mid;
            }
        }
    }

    public int sms4(byte[] in, int inLen, byte[] key, byte[] out, int CryptFlag) {
        int point = 0;
        int[] round_key = new int[ROUND];
        SMS4KeyExt(key, round_key, CryptFlag);
        byte[] input = new byte[16];
        byte[] output = new byte[16];

        while (inLen >= BLOCK) {
            input = Arrays.copyOfRange(in, point, point + 16);
            SMS4Crypt(input, output, round_key);
            System.arraycopy(output, 0, out, point, BLOCK);
            inLen -= BLOCK;
            point += BLOCK;
        }
        return 0;
    }
}

 android调用封装:

package com.wqk.teststring;

import android.util.Log;

public class Encryption {

    /**
     * SM4加解密封装
     * @param data 传入参数
     * @param flag 加密为1&解密为0
     * @param key 16字节密钥
     * @return 加解密结果
     */
    public static String deal(String data, int flag, byte[] key)
    {
        StringBuilder builder = new StringBuilder();
        SM4 sm4 = SM4.getInstance();
        String strData = "";
        byte[] bInData;
        byte[] bOutData = new byte[16];
        int nIndex;
        int nDataLen = data.length();
        int nCount = 0;
        int nLastLen = nDataLen%32;
        if (nLastLen > 0) {
            nCount = nDataLen/32 + 1;
            if (flag ==0) {
                Log.i("SM4", "数据长度不正确,需解密数据应是32的倍数");
            }
        } else {
            nCount = nDataLen/32;
        }
        for (int i = 0; i < nCount; i++) {
            if ((i+1) == nCount && nLastLen > 0) {
                nIndex = i*32;
                strData = data.substring(nIndex, nIndex+nLastLen);
                strData = zero(strData);
                bInData = hexStringToBytes(strData);
                sm4.sms4(bInData,bInData.length,key,bOutData,flag);
                strData = bytesToHexString(bOutData,0,16);
                builder.append(strData);
            } else {
                nIndex = i*32;
                strData = data.substring(nIndex, nIndex+32);
                bInData = hexStringToBytes(strData);
                sm4.sms4(bInData,bInData.length,key,bOutData,flag);
                strData = bytesToHexString(bOutData,0,16);
                builder.append(strData);
            }
        }
        return builder.toString();
    }

    /**
     * 补位方法,SM4 分块加密 ,每块16字节,此处不足补0. 扩展说明:有得规则是首字节补80,之后补00,还有区分左补和右补,如果此加解密不能满足要求,可以往这方面去做
     * @param data 需补位的数据
     * @return 补位后的字符串
     */
    public  static String zero(String data) {
        StringBuilder builder = new StringBuilder();
        builder.append(data);
        int nLen = data.length();
        while (nLen < 32) {
            builder.append("0");
            nLen++;
        }
        return builder.toString();
    }

    /**
     *  hexString转byte[]数组
     * @param str 字符串,原串为“112233”
     * @return 转换后的数据, 转换后为 0x11,0x22,0x33
     */
    public static byte[] hexStringToBytes(String str) {
        int charIndex, value;
        int datalen = str.length() / 2;
        byte[] data = new byte[datalen];
        for (int i = 0; i < datalen; i++) {
            charIndex = i * 2;
            value = Integer.parseInt(str.substring(charIndex, charIndex + 2), 16);
            data[i] = (byte) value;
        }

        return data;
    }

    /**
     * byte[]数组转hexString
     * @param data 需转换的数组 0x11,0x22,0x33
     * @param offset 需转换开始位置
     * @param len 需转换长度
     * @return 转换后的字符传为“112233”
     */
    public static String bytesToHexString(byte[] data, int offset, int len) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < len; i++)
            sb.append(String.format("%02X", data[i + offset] & 0xff));
        return sb.toString();
    }

}

Android调用

/*
* 两组示例数据(一)不定长字符串加密
* 加密数据:0123456789abcdeffedcba987654321011
* 密钥(k):0123456789abcdeffedcba9876543210
* 处理结果:681EDF34D206965E86B3E94F536E4246672FC13E4D9A6E324F8397329EF0B154
* 两组示例数据(二)定长字符串加密
* 加密数据:0123456789abcdeffedcba9876543210
* 密钥(k):0123456789abcdeffedcba9876543210
* 处理结果:681EDF34D206965E86B3E94F536E4246
* */
String strData = "0123456789abcdeffedcba9876543210";(十六进制字符串)
String strKey = "0123456789abcdeffedcba9876543210";
byte[] bKey = hexStringToBytes(strKey);(纯字符串,请使用string.getByte()转byte[])
String encryteData = Encryption.deal(strData,SM4.ENCRYPT,bKey);
Log.e("TAG", encryteData);加密结果:681EDF34D206965E86B3E94F536E4246

### Android 平台下的 SM4 加密解密方法 #### 添加依赖项 为了在 Android实现 SM4 的加密和解密功能,首先需要在 `app/build.gradle` 文件中添加 Bouncy Castle 库作为依赖项。这一步骤能够提供必要的工具来处理国密标准的加密操作。 ```gradle dependencies { implementation 'org.bouncycastle:bcprov-jdk15on:1.68' } ``` #### 编写 SM4 工具类 接着定义一个 Java 类用于封装 SM4 加密解密逻辑。此类内部实现了基于给定密钥字符串完成消息体加/解密的功能[^1]: ```java import org.bouncycastle.jce.provider.BouncyCastleProvider; import javax.crypto.Cipher; import javax.crypto.spec.SecretKeySpec; import java.security.Key; import java.util.Base64; public class Sm4Util { private static final String ALGORITHM_NAME = "SM4"; private static final String TRANSFORMATION_ECB_PKCS7_PADDING = "SM4/ECB/PKCS7Padding"; public byte[] encryptEcbPkcs7(byte[] key, byte[] data) throws Exception { Security.addProvider(new BouncyCastleProvider()); Key sm4Key = new SecretKeySpec(key, ALGORITHM_NAME); Cipher cipher = Cipher.getInstance(TRANSFORMATION_ECB_PKCS7_PADDING,"BC"); cipher.init(Cipher.ENCRYPT_MODE, sm4Key); return cipher.doFinal(data); } public byte[] decryptEcbPkcs7(byte[] key, byte[] encryptedData) throws Exception { Security.addProvider(new BouncyCastleProvider()); Key sm4Key = new SecretKeySpec(key, ALGORITHM_NAME); Cipher cipher = Cipher.getInstance(TRANSFORMATION_ECB_PKCS7_PADDING,"BC"); cipher.init(Cipher.DECRYPT_MODE, sm4Key); return cipher.doFinal(encryptedData); } // Base64编码函数 public String encodeBase64(byte[] bytes){ return Base64.getEncoder().encodeToString(bytes); } // Base64解码函数 public byte[] decodeBase64(String base64String){ return Base64.getDecoder().decode(base64String); } } ``` 上述代码展示了如何利用 ECB 模式的 PKCS7 填充方式执行基本的 SM4 加密与解密过程。需要注意的是实际应用时应考虑更复杂的场景如 CBC 模式以及 IV 向量等问题[^2]。 #### 测试案例 下面给出一段简单的测试代码片段展示如何调用上面创建的服务来进行 JSON 数据对象 `{\"salesNo\":\"123\",\"time\":123}` 的加密及随后的解密工作[^3]: ```java try{ Sm4Util util = new Sm4Util(); String jsonString = "{\"salesNo\":\"123\",\"time\":123}"; byte[] keyBytes = "your-secret-key-here".getBytes(); // 需要确保此key长度满足要求 // 执行加密操作并将结果转换成base64编码形式输出 byte[] encryptedData = util.encryptEcbPkcs7(keyBytes,jsonString.getBytes()); System.out.println("Encrypted Data (Base64): "+util.encodeBase64(encryptedData)); // 解密已加密的内容并打印原始json串 byte[] decryptedData = util.decryptEcbPkcs7(keyBytes,encryptedData); System.out.println("Decrypted Original Json :"+new String(decryptedData)); }catch(Exception e){ e.printStackTrace(); } ```
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