1、SM2簡述

　　RSA算法的危機在于其存在亞指數算法，對ECC算法而言一般沒有亞指數攻擊算法。

　　SM2橢圓曲線公鑰密碼算法：我國自主知識產權的商用密碼算法，是ECC（Elliptic Curve Cryptosystem）算法的一種，基于橢圓曲線離散對數問題，計算復雜度是指數級，求解難度較大，同等安全程度要求下，橢圓曲線密碼較其他公鑰算法所需密鑰長度小很多。

　　ECC算法描述：

用戶A選定一條適合加密的橢圓曲線Ep(a,b)(如:y2=x3+ax+b)，并取橢圓曲線上一點，作為基點G。
用戶A選擇一個私有密鑰k，并生成公開密鑰（公鑰P_B）K=kG。
用戶A將Ep(a,b)和點（公鑰）K，G傳給用戶B。
用戶B接到信息后，將待傳輸的明文（M）編碼到Ep(a,b)上一點M，并產生一個隨機整數r（r<n）。加密開始
用戶B計算點C1=M+rK；C2=rG。
用戶B將C1、C2傳給用戶A。
用戶A接到信息后，計算C1-kC2，結果就是點M。因為C1-kC2=M+rK-k(rG)=M+rK-r(kG)=M

　　再對點M進行解碼就可以得到明文。

　　密碼學中，描述一條Fp上的橢圓曲線，常用到六個參量：T=(p,a,b,G,n,h)。
　　（p 、a 、b 用來確定一條橢圓曲線，G為基點，n為點G的階，h 是橢圓曲線上所有點的個數m與n相除的整數部分）

　　這幾個參量取值的選擇，直接影響了加密的安全性。參量值一般要求滿足以下幾個條件：

p 當然越大越安全，但越大，計算速度會變慢，200位左右可以滿足一般安全要求；
p≠n×h；
pt≠1 (mod n)，1≤t<20；
4a3+27b2≠0 (mod p)；
n 為素數；
h≤4。

2、前后端代碼示例

　　1、Maven依賴

<!-- https://mvnrepository.com/artifact/org.bouncycastle/bcprov-jdk15on -->
<dependency>
    <groupId>org.bouncycastle</groupId>
    <artifactId>bcprov-jdk15on</artifactId>
    <version>1.56</version>
</dependency>

　　2、工具類Util

import java.math.BigInteger;

public class Util {
    /**
     * 整形轉換成網絡傳輸的字節流（字節數組）型數據
     *
     * @param num 一個整型數據
     * @return 4個字節的自己數組
     */
    public static byte[] intToBytes(int num) {
        byte[] bytes = new byte[4];
        bytes[0] = (byte) (0xff & (num >> 0));
        bytes[1] = (byte) (0xff & (num >> 8));
        bytes[2] = (byte) (0xff & (num >> 16));
        bytes[3] = (byte) (0xff & (num >> 24));
        return bytes;
    }

    /**
     * 四個字節的字節數據轉換成一個整形數據
     *
     * @param bytes 4個字節的字節數組
     * @return 一個整型數據
     */
    public static int byteToInt(byte[] bytes) {
        int num = 0;
        int temp;
        temp = (0x000000ff & (bytes[0])) << 0;
        num = num | temp;
        temp = (0x000000ff & (bytes[1])) << 8;
        num = num | temp;
        temp = (0x000000ff & (bytes[2])) << 16;
        num = num | temp;
        temp = (0x000000ff & (bytes[3])) << 24;
        num = num | temp;
        return num;
    }

    /**
     * 長整形轉換成網絡傳輸的字節流（字節數組）型數據
     *
     * @param num 一個長整型數據
     * @return 4個字節的自己數組
     */
    public static byte[] longToBytes(long num) {
        byte[] bytes = new byte[8];
        for (int i = 0; i < 8; i++) {
            bytes[i] = (byte) (0xff & (num >> (i * 8)));
        }

        return bytes;
    }

    /**
     * 大數字轉換字節流（字節數組）型數據
     *
     * @param n
     * @return
     */
    public static byte[] byteConvert32Bytes(BigInteger n) {
        byte tmpd[] = (byte[]) null;
        if (n == null) {
            return null;
        }

        if (n.toByteArray().length == 33) {
            tmpd = new byte[32];
            System.arraycopy(n.toByteArray(), 1, tmpd, 0, 32);
        } else if (n.toByteArray().length == 32) {
            tmpd = n.toByteArray();
        } else {
            tmpd = new byte[32];
            for (int i = 0; i < 32 - n.toByteArray().length; i++) {
                tmpd[i] = 0;
            }
            System.arraycopy(n.toByteArray(), 0, tmpd, 32 - n.toByteArray().length, n.toByteArray().length);
        }
        return tmpd;
    }

    /**
     * 換字節流（字節數組）型數據轉大數字
     *
     * @param b
     * @return
     */
    public static BigInteger byteConvertInteger(byte[] b) {
        if (b[0] < 0) {
            byte[] temp = new byte[b.length + 1];
            temp[0] = 0;
            System.arraycopy(b, 0, temp, 1, b.length);
            return new BigInteger(temp);
        }
        return new BigInteger(b);
    }

    /**
     * 根據字節數組獲得值(十六進制數字)
     *
     * @param bytes
     * @return
     */
    public static String getHexString(byte[] bytes) {
        return getHexString(bytes, true);
    }

    /**
     * 根據字節數組獲得值(十六進制數字)
     *
     * @param bytes
     * @param upperCase
     * @return
     */
    public static String getHexString(byte[] bytes, boolean upperCase) {
        String ret = "";
        for (int i = 0; i < bytes.length; i++) {
            ret += Integer.toString((bytes[i] & 0xff) + 0x100, 16).substring(1);
        }
        return upperCase ? ret.toUpperCase() : ret;
    }

    /**
     * 打印十六進制字符串
     *
     * @param bytes
     */
    public static void printHexString(byte[] bytes) {
        for (int i = 0; i < bytes.length; i++) {
            String hex = Integer.toHexString(bytes[i] & 0xFF);
            if (hex.length() == 1) {
                hex = '0' + hex;
            }
            System.out.print("0x" + hex.toUpperCase() + ",");
        }
        System.out.println("");
    }

    /**
     * Convert hex string to byte[]
     *
     * @param hexString the hex string
     * @return byte[]
     */
    public static byte[] hexStringToBytes(String hexString) {
        if (hexString == null || hexString.equals("")) {
            return null;
        }

        hexString = hexString.toUpperCase();
        int length = hexString.length() / 2;
        char[] hexChars = hexString.toCharArray();
        byte[] d = new byte[length];
        for (int i = 0; i < length; i++) {
            int pos = i * 2;
            d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));
        }
        return d;
    }

    /**
     * Convert char to byte
     *
     * @param c char
     * @return byte
     */
    public static byte charToByte(char c) {
        return (byte) "0123456789ABCDEF".indexOf(c);
    }

    /**
     * 用于建立十六進制字符的輸出的小寫字符數組
     */
    private static final char[] DIGITS_LOWER = {'0', '1', '2', '3', '4', '5',
            '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};

    /**
     * 用于建立十六進制字符的輸出的大寫字符數組
     */
    private static final char[] DIGITS_UPPER = {'0', '1', '2', '3', '4', '5',
            '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};

    /**
     * 將字節數組轉換為十六進制字符數組
     *
     * @param data byte[]
     * @return 十六進制char[]
     */
    public static char[] encodeHex(byte[] data) {
        return encodeHex(data, true);
    }

    /**
     * 將字節數組轉換為十六進制字符數組
     *
     * @param data        byte[]
     * @param toLowerCase <code>true</code> 傳換成小寫格式 ， <code>false</code> 傳換成大寫格式
     * @return 十六進制char[]
     */
    public static char[] encodeHex(byte[] data, boolean toLowerCase) {
        return encodeHex(data, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER);
    }

    /**
     * 將字節數組轉換為十六進制字符數組
     *
     * @param data     byte[]
     * @param toDigits 用于控制輸出的char[]
     * @return 十六進制char[]
     */
    protected static char[] encodeHex(byte[] data, char[] toDigits) {
        int l = data.length;
        char[] out = new char[l << 1];
        // two characters form the hex value.
        for (int i = 0, j = 0; i < l; i++) {
            out[j++] = toDigits[(0xF0 & data[i]) >>> 4];
            out[j++] = toDigits[0x0F & data[i]];
        }
        return out;
    }

    /**
     * 將字節數組轉換為十六進制字符串
     *
     * @param data byte[]
     * @return 十六進制String
     */
    public static String encodeHexString(byte[] data) {
        return encodeHexString(data, true);
    }

    /**
     * 將字節數組轉換為十六進制字符串
     *
     * @param data        byte[]
     * @param toLowerCase <code>true</code> 傳換成小寫格式 ， <code>false</code> 傳換成大寫格式
     * @return 十六進制String
     */
    public static String encodeHexString(byte[] data, boolean toLowerCase) {
        return encodeHexString(data, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER);
    }

    /**
     * 將字節數組轉換為十六進制字符串
     *
     * @param data     byte[]
     * @param toDigits 用于控制輸出的char[]
     * @return 十六進制String
     */
    protected static String encodeHexString(byte[] data, char[] toDigits) {
        return new String(encodeHex(data, toDigits));
    }

    /**
     * 將十六進制字符數組轉換為字節數組
     *
     * @param data 十六進制char[]
     * @return byte[]
     * @throws RuntimeException 如果源十六進制字符數組是一個奇怪的長度，將拋出運行時異常
     */
    public static byte[] decodeHex(char[] data) {
        int len = data.length;

        if ((len & 0x01) != 0) {
            throw new RuntimeException("Odd number of characters.");
        }

        byte[] out = new byte[len >> 1];

        // two characters form the hex value.
        for (int i = 0, j = 0; j < len; i++) {
            int f = toDigit(data[j], j) << 4;
            j++;
            f = f | toDigit(data[j], j);
            j++;
            out[i] = (byte) (f & 0xFF);
        }

        return out;
    }

    /**
     * 將十六進制字符轉換成一個整數
     *
     * @param ch    十六進制char
     * @param index 十六進制字符在字符數組中的位置
     * @return 一個整數
     * @throws RuntimeException 當ch不是一個合法的十六進制字符時，拋出運行時異常
     */
    protected static int toDigit(char ch, int index) {
        int digit = Character.digit(ch, 16);
        if (digit == -1) {
            throw new RuntimeException("Illegal hexadecimal character " + ch
                    + " at index " + index);
        }
        return digit;
    }

    /**
     * 數字字符串轉ASCII碼字符串
     *
     * @param content 字符串
     * @return ASCII字符串
     */
    public static String StringToAsciiString(String content) {
        String result = "";
        int max = content.length();
        for (int i = 0; i < max; i++) {
            char c = content.charAt(i);
            String b = Integer.toHexString(c);
            result = result + b;
        }
        return result;
    }

    /**
     * 十六進制轉字符串
     *
     * @param hexString  十六進制字符串
     * @param encodeType 編碼類型4：Unicode，2：普通編碼
     * @return 字符串
     */
    public static String hexStringToString(String hexString, int encodeType) {
        String result = "";
        int max = hexString.length() / encodeType;
        for (int i = 0; i < max; i++) {
            char c = (char) hexStringToAlgorism(hexString
                    .substring(i * encodeType, (i + 1) * encodeType));
            result += c;
        }
        return result;
    }

    /**
     * 十六進制字符串裝十進制
     *
     * @param hex 十六進制字符串
     * @return 十進制數值
     */
    public static int hexStringToAlgorism(String hex) {
        hex = hex.toUpperCase();
        int max = hex.length();
        int result = 0;
        for (int i = max; i > 0; i--) {
            char c = hex.charAt(i - 1);
            int algorism = 0;
            if (c >= '0' && c <= '9') {
                algorism = c - '0';
            } else {
                algorism = c - 55;
            }
            result += Math.pow(16, max - i) * algorism;
        }
        return result;
    }

    /**
     * 十六轉二進制
     *
     * @param hex 十六進制字符串
     * @return 二進制字符串
     */
    public static String hexStringToBinary(String hex) {
        hex = hex.toUpperCase();
        String result = "";
        int max = hex.length();
        for (int i = 0; i < max; i++) {
            char c = hex.charAt(i);
            switch (c) {
                case '0':
                    result += "0000";
                    break;
                case '1':
                    result += "0001";
                    break;
                case '2':
                    result += "0010";
                    break;
                case '3':
                    result += "0011";
                    break;
                case '4':
                    result += "0100";
                    break;
                case '5':
                    result += "0101";
                    break;
                case '6':
                    result += "0110";
                    break;
                case '7':
                    result += "0111";
                    break;
                case '8':
                    result += "1000";
                    break;
                case '9':
                    result += "1001";
                    break;
                case 'A':
                    result += "1010";
                    break;
                case 'B':
                    result += "1011";
                    break;
                case 'C':
                    result += "1100";
                    break;
                case 'D':
                    result += "1101";
                    break;
                case 'E':
                    result += "1110";
                    break;
                case 'F':
                    result += "1111";
                    break;
            }
        }
        return result;
    }

    /**
     * ASCII碼字符串轉數字字符串
     *
     * @param content ASCII字符串
     * @return 字符串
     */
    public static String AsciiStringToString(String content) {
        String result = "";
        int length = content.length() / 2;
        for (int i = 0; i < length; i++) {
            String c = content.substring(i * 2, i * 2 + 2);
            int a = hexStringToAlgorism(c);
            char b = (char) a;
            String d = String.valueOf(b);
            result += d;
        }
        return result;
    }

    /**
     * 將十進制轉換為指定長度的十六進制字符串
     *
     * @param algorism  int 十進制數字
     * @param maxLength int 轉換后的十六進制字符串長度
     * @return String 轉換后的十六進制字符串
     */
    public static String algorismToHexString(int algorism, int maxLength) {
        String result = "";
        result = Integer.toHexString(algorism);

        if (result.length() % 2 == 1) {
            result = "0" + result;
        }
        return patchHexString(result.toUpperCase(), maxLength);
    }

    /**
     * 字節數組轉為普通字符串（ASCII對應的字符）
     *
     * @param bytearray byte[]
     * @return String
     */
    public static String byteToString(byte[] bytearray) {
        String result = "";
        char temp;

        int length = bytearray.length;
        for (int i = 0; i < length; i++) {
            temp = (char) bytearray[i];
            result += temp;
        }
        return result;
    }

    /**
     * 二進制字符串轉十進制
     *
     * @param binary 二進制字符串
     * @return 十進制數值
     */
    public static int binaryToAlgorism(String binary) {
        int max = binary.length();
        int result = 0;
        for (int i = max; i > 0; i--) {
            char c = binary.charAt(i - 1);
            int algorism = c - '0';
            result += Math.pow(2, max - i) * algorism;
        }
        return result;
    }

    /**
     * 十進制轉換為十六進制字符串
     *
     * @param algorism int 十進制的數字
     * @return String 對應的十六進制字符串
     */
    public static String algorismToHEXString(int algorism) {
        String result = "";
        result = Integer.toHexString(algorism);

        if (result.length() % 2 == 1) {
            result = "0" + result;

        }
        result = result.toUpperCase();

        return result;
    }

    /**
     * HEX字符串前補0，主要用于長度位數不足。
     *
     * @param str       String 需要補充長度的十六進制字符串
     * @param maxLength int 補充后十六進制字符串的長度
     * @return 補充結果
     */
    static public String patchHexString(String str, int maxLength) {
        String temp = "";
        for (int i = 0; i < maxLength - str.length(); i++) {
            temp = "0" + temp;
        }
        str = (temp + str).substring(0, maxLength);
        return str;
    }

    /**
     * 將一個字符串轉換為int
     *
     * @param s          String 要轉換的字符串
     * @param defaultInt int 如果出現異常,默認返回的數字
     * @param radix      int 要轉換的字符串是什么進制的,如16 8 10.
     * @return int 轉換后的數字
     */
    public static int parseToInt(String s, int defaultInt, int radix) {
        int i = 0;
        try {
            i = Integer.parseInt(s, radix);
        } catch (NumberFormatException ex) {
            i = defaultInt;
        }
        return i;
    }

    /**
     * 將一個十進制形式的數字字符串轉換為int
     *
     * @param s          String 要轉換的字符串
     * @param defaultInt int 如果出現異常,默認返回的數字
     * @return int 轉換后的數字
     */
    public static int parseToInt(String s, int defaultInt) {
        int i = 0;
        try {
            i = Integer.parseInt(s);
        } catch (NumberFormatException ex) {
            i = defaultInt;
        }
        return i;
    }

    /**
     * 十六進制串轉化為byte數組
     *
     * @return the array of byte
     */
    public static byte[] hexToByte(String hex)
            throws IllegalArgumentException {
        if (hex.length() % 2 != 0) {
            throw new IllegalArgumentException();
        }
        if (hex.length() < 1) {
            return null;
        } else {
            byte[] result = new byte[hex.length() / 2];
            int j = 0;
            for(int i = 0; i < hex.length(); i+=2) {
                result[j++] = (byte)Integer.parseInt(hex.substring(i,i+2), 16);
            }
            return result;
        }
    }

    /**
     * 字節數組轉換為十六進制字符串
     *
     * @param b byte[] 需要轉換的字節數組
     * @return String 十六進制字符串
     */
    public static String byteToHex(byte b[]) {
        if (b == null) {
            return "";
        }
        StringBuffer sb = new StringBuffer();
        for(int i = 0; i < b.length; i++) {
            String hex = Integer.toHexString(b[i] & 0xFF);
            if(hex.length() < 2) {
                hex = "0" + hex;
            }
            sb.append(hex.toUpperCase());
        }
        return sb.toString();
    }

    public static byte[] subByte(byte[] input, int startIndex, int length) {
        byte[] bt = new byte[length];
        for (int i = 0; i < length; i++) {
            bt[i] = input[i + startIndex];
        }
        return bt;
    }
}

　　3、參數類SM2

import org.bouncycastle.crypto.generators.ECKeyPairGenerator;
import org.bouncycastle.crypto.params.ECDomainParameters;
import org.bouncycastle.crypto.params.ECKeyGenerationParameters;
import org.bouncycastle.math.ec.ECCurve;
import org.bouncycastle.math.ec.ECFieldElement;
import org.bouncycastle.math.ec.ECFieldElement.Fp;
import org.bouncycastle.math.ec.ECPoint;

import java.math.BigInteger;
import java.security.SecureRandom;

public class SM2 {

    //國密參數
    public static String[] ecc_param = {
            "FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFF",
            "FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFC",
            "28E9FA9E9D9F5E344D5A9E4BCF6509A7F39789F515AB8F92DDBCBD414D940E93",
            "FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFF7203DF6B21C6052B53BBF40939D54123",
            "32C4AE2C1F1981195F9904466A39C9948FE30BBFF2660BE1715A4589334C74C7",
            "BC3736A2F4F6779C59BDCEE36B692153D0A9877CC62A474002DF32E52139F0A0"
    };

    public static SM2 Instance() {
        return new SM2();
    }

    /** 素數p */
    public final BigInteger ecc_p;
    /** 系數a */
    public final BigInteger ecc_a;
    /** 系數b */
    public final BigInteger ecc_b;
    /** 基點G, G=(xg,yg),其介記為n */
    public final BigInteger ecc_n;
    /** 坐標x */
    public final BigInteger ecc_gx;
    /** 坐標y */
    public final BigInteger ecc_gy;
    public final ECCurve ecc_curve;
    public final ECPoint ecc_point_g;
    public final ECDomainParameters ecc_bc_spec;
    public final ECKeyPairGenerator ecc_key_pair_generator;
    public final ECFieldElement ecc_gx_fieldelement;
    public final ECFieldElement ecc_gy_fieldelement;

    public SM2() {
        this.ecc_p = new BigInteger(ecc_param[0], 16);
        this.ecc_a = new BigInteger(ecc_param[1], 16);
        this.ecc_b = new BigInteger(ecc_param[2], 16);
        this.ecc_n = new BigInteger(ecc_param[3], 16);
        this.ecc_gx = new BigInteger(ecc_param[4], 16);
        this.ecc_gy = new BigInteger(ecc_param[5], 16);

        this.ecc_gx_fieldelement = new Fp(this.ecc_p, this.ecc_gx);
        this.ecc_gy_fieldelement = new Fp(this.ecc_p, this.ecc_gy);

        this.ecc_curve = new ECCurve.Fp(this.ecc_p, this.ecc_a, this.ecc_b);
        this.ecc_point_g = new ECPoint.Fp(this.ecc_curve, this.ecc_gx_fieldelement, this.ecc_gy_fieldelement);

        this.ecc_bc_spec = new ECDomainParameters(this.ecc_curve, this.ecc_point_g, this.ecc_n);

        ECKeyGenerationParameters ecc_ecgenparam;
        ecc_ecgenparam = new ECKeyGenerationParameters(this.ecc_bc_spec, new SecureRandom());

        this.ecc_key_pair_generator = new ECKeyPairGenerator();
        this.ecc_key_pair_generator.init(ecc_ecgenparam);
    }
}

　　4、Cipher

import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.digests.SM3Digest;
import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.math.ec.ECPoint;

import java.math.BigInteger;

public class Cipher {
    private int ct;
    private ECPoint p2;
    private SM3Digest sm3keybase;
    private SM3Digest sm3c3;
    private byte key[];
    private byte keyOff;

    public Cipher()
    {
        this.ct = 1;
        this.key = new byte[32];
        this.keyOff = 0;
    }

    private void Reset()
    {
        this.sm3keybase = new SM3Digest();
        this.sm3c3 = new SM3Digest();

        byte p[] = Util.byteConvert32Bytes(p2.getX().toBigInteger());
        this.sm3keybase.update(p, 0, p.length);
        this.sm3c3.update(p, 0, p.length);

        p = Util.byteConvert32Bytes(p2.getY().toBigInteger());
        this.sm3keybase.update(p, 0, p.length);
        this.ct = 1;
        NextKey();
    }

    private void NextKey()
    {
        SM3Digest sm3keycur = new SM3Digest(this.sm3keybase);
        sm3keycur.update((byte) (ct >> 24 & 0xff));
        sm3keycur.update((byte) (ct >> 16 & 0xff));
        sm3keycur.update((byte) (ct >> 8 & 0xff));
        sm3keycur.update((byte) (ct & 0xff));
        sm3keycur.doFinal(key, 0);
        this.keyOff = 0;
        this.ct++;
    }

    public ECPoint Init_enc(SM2 sm2, ECPoint userKey)
    {
        AsymmetricCipherKeyPair key = sm2.ecc_key_pair_generator.generateKeyPair();
        ECPrivateKeyParameters ecpriv = (ECPrivateKeyParameters) key.getPrivate();
        ECPublicKeyParameters ecpub = (ECPublicKeyParameters) key.getPublic();
        BigInteger k = ecpriv.getD();
        ECPoint c1 = ecpub.getQ();
        this.p2 = userKey.multiply(k);
        Reset();
        return c1;
    }

    public void Encrypt(byte data[])
    {
        this.sm3c3.update(data, 0, data.length);
        for (int i = 0; i < data.length; i++)
        {
            if (keyOff == key.length)
            {
                NextKey();
            }
            data[i] ^= key[keyOff++];
        }
    }

    public void Init_dec(BigInteger userD, ECPoint c1)
    {
        this.p2 = c1.multiply(userD);
        Reset();
    }

    public void Decrypt(byte data[])
    {
        for (int i = 0; i < data.length; i++)
        {
            if (keyOff == key.length)
            {
                NextKey();
            }
            data[i] ^= key[keyOff++];
        }

        this.sm3c3.update(data, 0, data.length);
    }

    public void Dofinal(byte c3[])
    {
        byte p[] = Util.byteConvert32Bytes(p2.getY().toBigInteger());
        this.sm3c3.update(p, 0, p.length);
        this.sm3c3.doFinal(c3, 0);
        Reset();
    }
}

　　5、功能類SM2EncDecUtils

import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.math.ec.ECPoint;

import java.io.IOException;
import java.math.BigInteger;
import java.util.HashMap;
import java.util.Map;

public class SM2EncDecUtils {

    public static final String public_key = "public_key";
    public static final String private_key = "private_key";

    // 生成隨機秘鑰對
    public static Map<String, String> generateKeyPair() {
        SM2 sm2 = SM2.Instance();
        AsymmetricCipherKeyPair key = null;
        while (true) {
            key = sm2.ecc_key_pair_generator.generateKeyPair();
            if (((ECPrivateKeyParameters) key.getPrivate()).getD().toByteArray().length == 32) {
                break;
            }
        }
        ECPrivateKeyParameters ecpriv = (ECPrivateKeyParameters) key.getPrivate();
        ECPublicKeyParameters ecpub = (ECPublicKeyParameters) key.getPublic();
        BigInteger privateKey = ecpriv.getD();
        ECPoint publicKey = ecpub.getQ();
        String pubk = Util.byteToHex(publicKey.getEncoded());
        String prik = Util.byteToHex(privateKey.toByteArray());
        System.out.println("公鑰: " + pubk);
        System.out.println("私鑰: " + prik);
        Map<String, String> result = new HashMap<>();

        result.put(public_key, pubk);
        result.put(private_key, prik);

        return result;
    }

    // 數據加密
    public static String encrypt(byte[] publicKey, byte[] data) throws IOException {
        if (publicKey == null || publicKey.length == 0) {
            return null;
        }

        if (data == null || data.length == 0) {
            return null;
        }

        byte[] source = new byte[data.length];
        System.arraycopy(data, 0, source, 0, data.length);
        Cipher cipher = new Cipher();
        SM2 sm2 = SM2.Instance();
        ECPoint userKey = sm2.ecc_curve.decodePoint(publicKey);
        ECPoint c1 = cipher.Init_enc(sm2, userKey);
        cipher.Encrypt(source);
        byte[] c3 = new byte[32];
        cipher.Dofinal(c3);
        return new StringBuffer(Util.byteToHex(c1.getEncoded())).append(Util.byteToHex(c3)).append(Util.byteToHex(source)).toString();
    }

    // 數據解密
    public static byte[] decrypt(byte[] privateKey, byte[] encryptedData) throws IOException {
        if (privateKey == null || privateKey.length == 0) {
            return null;
        }

        if (encryptedData == null || encryptedData.length == 0) {
            return null;
        }
        // 加密字節數組轉換為十六進制的字符串 長度變為encryptedData.length * 2
        String data = Util.byteToHex(encryptedData);

        byte[] c1Bytes = Util.hexToByte(data.substring(0, 130));
        int c2Len = encryptedData.length - 97;
        byte[] c3 = Util.hexToByte(data.substring(130, 130 + 64));
        byte[] c2 = Util.hexToByte(data.substring(194, 194 + 2 * c2Len));

        SM2 sm2 = SM2.Instance();
        BigInteger userD = new BigInteger(1, privateKey);

        // 通過C1實體字節來生成ECPoint
        ECPoint c1 = sm2.ecc_curve.decodePoint(c1Bytes);
        Cipher cipher = new Cipher();
        cipher.Init_dec(userD, c1);
        cipher.Decrypt(c2);
        cipher.Dofinal(c3);

        // 返回解密結果
        return c2;
    }

    public static void main(String[] args) throws Exception {

        singleThreadTest();
//        mutiThreadTest();
    }

    private static void singleThreadTest() throws Exception {
        String plainText = "sourceText";
        byte[] sourceData = plainText.getBytes();
        Map<String, String> keymap = generateKeyPair();

        long start = System.currentTimeMillis();
        int counts = 100;
        for (int j = 0; j < counts; j++) {
            String cipherText = SM2EncDecUtils.encrypt(Util.hexToByte(keymap.get(public_key)), sourceData);
            System.out.println("加密前長度: " + plainText.length() + ";加密后長度: " + cipherText.length());
            String plainTextEncripted = new String(SM2EncDecUtils.decrypt(Util.hexToByte(keymap.get(private_key)), Util.hexToByte(cipherText)));
            if (plainText.equals(plainTextEncripted)) {
                System.out.println("------解密后同原文是否一致: " + plainText.equals(plainTextEncripted) + "----------------------");
            }
        }
        long end = System.currentTimeMillis();
        System.out.println("平均耗時:" + (end - start) / counts + "ms。");
    }

    private static void mutiThreadTest() {
        String plainText = "sourceText";
        byte[] sourceData = plainText.getBytes();

        Map<String, String> keymap = generateKeyPair();
        int counts = 10;
        for (int i = 0; i < counts; i++) {
            new Thread(() -> {
                try {
                    for (int j = 0; j < counts; j++) {
                        String cipherText = SM2EncDecUtils.encrypt(Util.hexToByte(keymap.get(public_key)), sourceData);
                        if (!plainText.equals(new String(SM2EncDecUtils.decrypt(Util.hexToByte(keymap.get(private_key)), Util.hexToByte(cipherText))))) {
                            System.out.println("------解密后同原文不一致:" + Thread.currentThread().getName() + "--------------");
                        }
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
                System.out.println(" --------------->線程" + Thread.currentThread().getName() + "執行完成.---------------------");
            }
            ).start();
        }
    }
}

　　6、測試

　　測試結果如下：

公鑰: 04D4BDF1A660C728418D685A702C5E16EAA2463471BC23107CBDBBB4AD7AF526F88E89EBC7D3075D826F8323657858A351A709423B18A685CDAD141E671C32E8D4
私鑰: 0AC55910CF19346F35324577E7F3F0C544A7823B154B756D63160FD1167992B2

加密前長度: 10，明文為: sourceText
加密后長度: 214，加密后密文為: 0408F3F31B4B19D7C9E655A7711F3901B908EFA8C38F9F06B1B43622D01657B6BED9A7F61DF01DDFF91DDB82C69004C910E70550A982FEDBD87839756F035E8EA653DEAEAB58D35696A16A10BC943CF98776ECEB4DF81823B535A3DDEA71FF46932677EECB2A98077617B5
------解密后同原文是否一致: true----------------------

加密前長度: 10，明文為: sourceText
加密后長度: 214，加密后密文為: 04788D945B48902DF9C3D445849A97E86C37E65F6A9E1B3A126DD4942CF0545EE485401EF0F240B7F7CEE69926E42C7697F1064349594E29C7A715F5BC0CE3968B959DB64D0AB53F9CC692ED97E32FBB3CE579AB31B4116F40A8BF380A3B8BB550A525ED92E3233B457336
------解密后同原文是否一致: true----------------------
平均耗時:22ms。

　　可以看出加密長度每次是穩定的，但是加密后密文是不一樣的，但是解密后結果都是一樣的。

　　7、VUE代碼

const sm2 = require('sm-crypto').sm2
const cipherMode = 1 // 1 - C1C3C2，0 - C1C2C3，默認為1
const publicKey = "04D4BDF1A660C728418D685A702C5E16EAA2463471BC23107CBDBBB4AD7AF526F88E89EBC7D3075D826F8323657858A351A709423B18A685CDAD141E671C32E8D4"
 
// 加密
export function encrypt(txt) {
    let encryptData = sm2.doEncrypt(txt, publicKey, 1) // 加密結果
    return '04' + encryptData;
}

　　注意：最關鍵的是VUE加密完的密文要加“04”，后端解密才能成功，否則后端解密16進制字符串轉字節數組的時候會有問題；

　　同理后端加密的密文要刪除開頭的“04”，VUE才能解密成功。通過上面測試結果可以看出密文是以“04”開頭的。

posted on 2021-06-22 20:10 kosamino 閱讀(7447) 評論(7) 收藏舉報