SM2，SM3，SM4演算法的實現在網路上實現有不少，但是實現只是加解密，簽名等，如果說要生成國密數字證書就麻煩了，還有最近銀行的專案上需要用ITEXT對pdf進行國密跟RSA證書數字簽名，這個用SM2單獨的簽名是不能實現的，因為ITEXT簽名是基於BC框架的，這裡就是在BC框架上新增SM2，SM4演算法，以及SM3摘要演算法，在這裡跟大家分享一下。
BC框架是基於JCA，JCE來實現的，關於JCA，JCE這裡就不詳述了。既然我們要新增這幾種演算法，我們要實現那幾步呢？
1，實現MAC
2，實現SM2，SM3，SM4演算法
3，SM2，SM4演算法的金鑰（KeyPairGenerator）
4，加解密（Cipher）；
5，簽名（Signature）；
6，數字證書（Certificate）
話不多說，先上幾張效果圖。
一 ，SM2加解密

 public static String SM2_Cipher(boolean all,String enData) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
        StringBuilder sb = new StringBuilder();
        byte[] sourceData = enData.getBytes();
        KeyPair keyPair = generateKeyPair(all?sb:null);
 

        Cipher cp1 = Cipher.getInstance("SM2");
        sb.append("public key = ");
        sb.append(bytesToHexString(keyPair.getPublic().getEncoded()));
        sb.append("\nprivate key = ");
        sb.append(bytesToHexString(keyPair.getPrivate().getEncoded()));

        cp1.init(1, keyPair.getPublic
 
());
        byte[] encrypted = cp1.doFinal(sourceData);
        sb.append("\nEncrypted: ");
        sb.append(bytesToHexString(encrypted));
        Cipher cp2 = Cipher.getInstance("SM2");
        cp2.init(2, keyPair.getPrivate());
        byte[] decrypted = cp2.doFinal(encrypted);
        sb.append("\nDecrypted: ");
        sb.append(bytesToHexString(decrypted));
        sb.append("\nDecryptString: ");
        sb.append(new String(decrypted));
        boolean equ = Arrays.equals(decrypted, sourceData);
        sb.append("\nEncrypt/Decrypt ").append(equ?"Passed.":"Failed.");
        return sb.toString();
    }

    public static KeyPair generateKeyPair(StringBuilder sb) throws NoSuchAlgorithmException {
        addProvider((StringBuilder)null);
        KeyPairGenerator kpg = KeyPairGenerator.getInstance("SM2");
        return kpg.generateKeyPair();
    }

二，SM4加解密

public static String SM4_Cipher(boolean all,String enData) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
        StringBuilder sb = new StringBuilder();
        byte[] sourceData = enData.getBytes();
        byte[] sorData_16 = new byte[16];
        System.arraycopy(sourceData,0,sorData_16,0,sourceData.length);
        addProvider(all?sb:null);
        KeyGenerator kg = KeyGenerator.getInstance("SM4");
        kg.init(new SecureRandom());
        SecretKey keye = kg.generateKey();
        byte[] sm4k = keye.getEncoded();
        sb.append("\nKey:");
        sb.append(bytesToHexString(sm4k));
        SecretKeySpec keyd = new SecretKeySpec(sm4k, "SM4");
        Cipher cp1 = Cipher.getInstance("SM4");
        cp1.init(1, keye);
        byte[] encrypted = cp1.doFinal(sorData_16);
        sb.append("\nEncrypted: ");
        sb.append(bytesToHexString(encrypted));
        Cipher cp2 = Cipher.getInstance("SM4");
        cp2.init(2, keyd);
        byte[] decrypted = cp2.doFinal(encrypted);
        sb.append("\nDecrypted: ");
        sb.append(bytesToHexString(decrypted));
        sb.append("\nDecryptString: ");
        sb.append(new String(decrypted));
        if(Arrays.equals(sorData_16, decrypted)) {
            sb.append("\nSM4 Ok.");
        }

        return sb.toString();
    }

三，SM2證書以及簽名

“`
public static String testSM2() throws NoSuchAlgorithmException, OperatorCreationException, CertificateException, CertIOException, CertException {
StringBuilder sb = new StringBuilder();
SecureRandom apRandom = new SecureRandom();
NameBuilder nb = new NameBuilder(RDN.INSTANCE);
nb.addRDN(RDN.E, “[email protected]”);
nb.addRDN(RDN.CN, “gongkan”);
nb.addRDN(RDN.T, “CEO”);
nb.addRDN(RDN.OU, “unipad”);
nb.addRDN(RDN.O, “科技園”);
nb.addRDN(RDN.L, “深圳”);
nb.addRDN(RDN.ST, “廣東”);
BigInteger serial = (new BigInteger(31, apRandom)).abs();
Date notBefore = new Date();
Date notAfter = new Date(notBefore.getTime() + 259200000L);
KeyPair keyPair = genSM2KeyPair();
PublicKey publicKey = keyPair.getPublic();
X500Principal me = nb.toName();
X509v3CertBuilder x3b = new X509v3CertBuilder(me, serial, notBefore, notAfter, me, publicKey);
x3b.addExtension(Extension.basicConstraints, true, new BasicConstraints(false));
x3b.addExtension(Extension.keyUsage, false, new KeyUsage(184));
x3b.addExtension(Extension.extendedKeyUsage, false, new ExtendedKeyUsage(new KeyPurposeId[]{KeyPurposeId.id_kp_emailProtection, KeyPurposeId.id_kp_clientAuth}));
PrivateKey privateKey = keyPair.getPrivate();
ContentSigner signer = (new SM2SignerBuilder(“1234567812345678”)).build(privateKey);
X509CertificateHolder xchd = x3b.build(signer);
X509CertificateConverter xcvt = (new X509CertificateConverter()).setProvider(“SM”);
X509Certificate cert = xcvt.getCertificate(xchd);
CertificateFactory factory = CertificateFactory.getInstance(“X509/SM2”);
X509Certificate cer = (X509Certificate)factory.generateCertificate(new ByteArrayInputStream(cert.getEncoded()));
sb.append(cer);
sb.append(“\nVerify Certificate “);

    try {
        cer.verify(publicKey);
        sb.append("Passed.");
    } catch (GeneralSecurityException var18) {
        var18.printStackTrace();
        sb.append("Failed.");
    }

    return sb.toString();
}

四，專案結構圖