package com.zpc.cryptography;


import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.math.BigInteger;
import java.util.Enumeration;


import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1InputStream;
import org.bouncycastle.asn1.ASN1Integer;
import org.bouncycastle.asn1.ASN1Primitive;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.DERInteger;
import org.bouncycastle.asn1.DEROctetString;
import org.bouncycastle.asn1.DEROutputStream;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.math.ec.ECPoint;
import org.bouncycastle.util.encoders.Base64;


public class SM2Utils {


public static byte[] 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);

    DERInteger x = new DERInteger(c1.getX().toBigInteger());
    DERInteger y = new DERInteger(c1.getY().toBigInteger());
    DEROctetString derDig = new DEROctetString(c3);
    DEROctetString derEnc = new DEROctetString(source);
    ASN1EncodableVector v = new ASN1EncodableVector();
    v.add(x);
    v.add(y);
    v.add(derDig);
    v.add(derEnc);
    DERSequence seq = new DERSequence(v);
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    DEROutputStream dos = new DEROutputStream(bos);
    dos.writeObject(seq);
    return bos.toByteArray();
}

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;
    }

    byte[] enc = new byte[encryptedData.length];
    System.arraycopy(encryptedData, 0, enc, 0, encryptedData.length);

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

    ByteArrayInputStream bis = new ByteArrayInputStream(enc);
    ASN1InputStream dis = new ASN1InputStream(bis);
    ASN1Primitive derObj = dis.readObject();
    //DERObject derObj = dis.readObject();
    ASN1Sequence asn1 = (ASN1Sequence) derObj;
    //DERInteger x = (DERInteger) asn1.getObjectAt(0);
    //DERInteger y = (DERInteger) asn1.getObjectAt(1);
    ASN1Integer x = (ASN1Integer) asn1.getObjectAt(0);
    ASN1Integer y = (ASN1Integer) asn1.getObjectAt(1);
    ECPoint c1 = sm2.ecc_curve.createPoint(x.getValue(), y.getValue(), true);

    Cipher cipher = new Cipher();
    cipher.Init_dec(userD, c1);
    DEROctetString data = (DEROctetString) asn1.getObjectAt(3);
    enc = data.getOctets();
    cipher.Decrypt(enc);
    byte[] c3 = new byte[32];
    cipher.Dofinal(c3);
    return enc;
}

/**
 * 签名
 *
 * @param userId
 * @param privateKey
 * @param sourceData
 * @return
 * @throws IOException
 */
public static byte[] sign(byte[] userId, byte[] privateKey, byte[] sourceData) throws IOException {

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

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

    SM2 sm2 = SM2.Instance();
    BigInteger userD = new BigInteger(privateKey);
    //System.out.println("userD: " + userD.toString(16));
    //System.out.println("");

    ECPoint userKey = sm2.ecc_point_g.multiply(userD);
    //System.out.println("椭圆曲线点X: " + userKey.getX().toBigInteger().toString(16));
    //System.out.println("椭圆曲线点Y: " + userKey.getY().toBigInteger().toString(16));
    //System.out.println("");


    byte[] z = sm2.sm2GetZ(userId, userKey);
    //System.out.println("SM3摘要Z: " + Util.getHexString(z));
    //System.out.println("");

    //System.out.println("M: " + Util.getHexString(sourceData));
    //System.out.println("");

    SM3Digest sm3 = new SM3Digest();
    sm3.update(z, 0, z.length);
    sm3.update(sourceData, 0, sourceData.length);
    byte[] md = new byte[32];
    sm3.doFinal(md, 0);

    //System.out.println("SM3摘要值: " + Util.getHexString(md));
    //System.out.println("");

    SM2Result sm2Result = new SM2Result();
    sm2.sm2Sign(md, userD, userKey, sm2Result);
    //System.out.println("r: " + sm2Result.r.toString(16));
    //System.out.println("s: " + sm2Result.s.toString(16));
    //System.out.println("");

    DERInteger d_r = new DERInteger(sm2Result.r);
    DERInteger d_s = new DERInteger(sm2Result.s);
    ASN1EncodableVector v2 = new ASN1EncodableVector();
    v2.add(d_r);
    v2.add(d_s);
    DERSequence sign = new DERSequence(v2);
    //DERObject sign = new DERSequence(v2);
    //byte[] signdata = sign.getDEREncoded();
    byte[] signdata = sign.getEncoded();

    return signdata;
}

@SuppressWarnings("unchecked")
public static boolean verifySign(byte[] userId, byte[] publicKey, byte[] sourceData, byte[] signData) throws IOException {

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

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

    SM2 sm2 = SM2.Instance();
    ECPoint userKey = sm2.ecc_curve.decodePoint(publicKey);

    SM3Digest sm3 = new SM3Digest();
    byte[] z = sm2.sm2GetZ(userId, userKey);
    sm3.update(z, 0, z.length);
    sm3.update(sourceData, 0, sourceData.length);
    byte[] md = new byte[32];
    sm3.doFinal(md, 0);
    //System.out.println("SM3摘要值: " + Util.getHexString(md));
    //System.out.println("");

    ByteArrayInputStream bis = new ByteArrayInputStream(signData);
    ASN1InputStream dis = new ASN1InputStream(bis);
    //DERObject derObj = dis.readObject();
    ASN1Primitive derObj = dis.readObject();
    Enumeration<ASN1Integer> e = ((ASN1Sequence) derObj).getObjects();
    BigInteger r = e.nextElement().getValue();
    BigInteger s = e.nextElement().getValue();
    SM2Result sm2Result = new SM2Result();
    sm2Result.r = r;
    sm2Result.s = s;
    //System.out.println("r: " + sm2Result.r.toString(16));
    //System.out.println("s: " + sm2Result.s.toString(16));
    //System.out.println("");


    sm2.sm2Verify(md, userKey, sm2Result.r, sm2Result.s, sm2Result);
    return sm2Result.r.equals(sm2Result.R);
}

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


    String plainText = "message digest";
    //1.源数据数组
    byte[] sourceData = plainText.getBytes();

    // 国密规范测试私钥
    String prik = "128B2FA8BD433C6C068C8D803DFF79792A519A55171B1B650C23661D15897263";
    //2.私钥先转十六进制，然后进行Base64编码
    String prikS = new String(Base64.encode(Util.hexToByte(prik)));
    System.out.println("转换后的私钥：prikS====" + prikS);
    //System.out.println("");

    // 国密规范测试用户ID
    String userId = "[email protected]";

    //获取userId十六进制字符串
    System.out.println("十六进制userId: " + Util.getHexString(userId.getBytes()));
    //System.out.println("");

    //System.out.println("签名: ");
    //3.用userId和私钥，对明文数据签名(userid、prik、sourceData)
    byte[] c = SM2Utils.sign(userId.getBytes(), Base64.decode(prikS.getBytes()), sourceData);
    System.out.println("SM2签名后值====" + Util.getHexString(c));
    //System.out.println("");

    // 国密规范测试公钥
    String pubk = "040AE4C7798AA0F119471BEE11825BE46202BB79E2A5844495E97C04FF4DF2548A7C0240F88F1CD4E16352A73C17B7F16F07353E53A176D684A9FE0C6BB798E857";
    String pubkS = new String(Base64.encode(Util.hexToByte(pubk)));
    System.out.println("转换后的公钥pubkS====" + pubkS);
    //System.out.println("");


    //System.out.println("验签: ");
    //4.用公钥进行验签(userId、pubk、sourceData、签名数据c)
    boolean vs = SM2Utils.verifySign(userId.getBytes(), Base64.decode(pubkS.getBytes()), sourceData, c);
    System.out.println("验签结果: " + vs);
    //System.out.println("");

    //System.out.println("加密: ");
    //5.SM2加密算法
    byte[] cipherText = SM2Utils.encrypt(Base64.decode(pubkS.getBytes()), sourceData);
    System.out.println("SM2加密后结果===" + new String(Base64.encode(cipherText)));
    System.out.println("");

    //System.out.println("解密: ");
    //6.SM2解密算法
    plainText = new String(SM2Utils.decrypt(Base64.decode(prikS.getBytes()), cipherText));
    System.out.println("解密后获取的结果===" + plainText);

}
}

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