Java解析证书内容

Java解析证书获取证书内部信息，在证书交换环节中常使用，网络上也提供很多参考方案，本文主要是提供证书base64格式解析和证书路径解析证书内容。在解析时可能会遇到一些问题，后面根据情况再具体说明。

首先提供的是解析base64格式证书

引入pom依赖

<dependency>
<groupId>org.bouncycastle</groupId>
<artifactId>bcpkix-jdk15on</artifactId>
<version>1.70</version>
</dependency>
<dependency>
<groupId>org.bouncycastle</groupId>
<artifactId>bcprov-jdk15on</artifactId>
<version>1.70</version>
</dependency>

编写公共方法

import org.bouncycastle.asn1.*;
import org.bouncycastle.asn1.x509.*;
import org.bouncycastle.util.encoders.Hex;
import sun.misc.BASE64Decoder;
import java.io.*;
import java.security.cert.*;
import java.util.HashMap;

public class CertUtil {

/**
* x509证书解析
*
* @param
* @return
*/
public static void getCertInfo(byte[] Cert) {
InputStream inStream = new ByteArrayInputStream(Cert);
ASN1Sequence seq;
ASN1InputStream aIn;
try{
aIn = new ASN1InputStream(inStream);
seq = (ASN1Sequence)aIn.readObject();
X509CertificateStructure cert = new X509CertificateStructure(seq);

String endDate = cert.getEndDate().getTime();
String startDate = cert.getStartDate().getTime();
System.out.println("endDate============="+endDate);
System.out.println("startDate============="+startDate);
int version = cert.getVersion();
System.out.println("cert.getVersion()============="+cert.getVersion());
X509Name issuer = cert.getIssuer();
X509Name subject = cert.getSubject();
System.out.println("issuer============="+issuer);
System.out.println("subject============="+subject);
String serialNumber = cert.getSerialNumber().getValue().toString(16);
System.out.println("serialNumber============="+serialNumber);
DERBitString signature = cert.getSignature();
String sign = new String(Hex.encode(signature.getBytes()));
System.out.println("sign============="+sign);
SubjectPublicKeyInfo publicKeyInfo = cert.getSubjectPublicKeyInfo();
String algId = publicKeyInfo.getAlgorithmId().getObjectId().getId();
System.out.println("algId============="+algId);
byte[] byPuk = publicKeyInfo.getPublicKeyData().getBytes();
String publicKey = new String(Hex.encode(byPuk));
System.out.println("publicKey============="+publicKey);
} catch (Exception e) {
e.printStackTrace();
}
}

/**
* x509证书解析重载
*
* @param cert
* @return
*/
public static HashMap<String, Object> getCert(String cert) {
cert = cert.replaceAll("\r", "");
cert = cert.replaceAll("\n", "");
cert = cert.replace("-----BEGIN CERTIFICATE-----", "");
cert = cert.replace("-----END CERTIFICATE-----", "");

BASE64Decoder decoder = new BASE64Decoder();
try {
return getCertInfo(decoder.decodeBuffer(cert));
} catch (IOException e) {
e.printStackTrace();
}

return null;
}
}

证书路径解析证书

引入pom依赖

<dependency><groupId>org.bouncycastle</groupId><artifactId>bcprov-jdk15on</artifactId><version>1.61</version>
</dependency>
<dependency><groupId>org.bouncycastle</groupId><artifactId>bcprov-jdk15on</artifactId><version>1.67</version>
</dependency>

编写公共方法

public static HashMap<String, Object> getCertCate(String certPath) {
HashMap<String, Object> certinfo = new HashMap<>();
try{
// 引入BC库
Security.addProvider(new BouncyCastleProvider());
// 使用BC解析X.509证书
CertificateFactory CF = CertificateFactory.getInstance("X.509", "BC"); // 从证书工厂中获取X.509的单例类
InputStream fileIn = new FileInputStream(certPath); // 将本地证书读入文件流
Certificate C = CF.generateCertificate(fileIn); // 将文件流的证书转化为证书类
String certificateStr = C.toString();
System.out.println("使用[自带库函数]读入证书结果如下：");
System.out.print(certificateStr);
System.out.println("--------------------------------------\n证书主要字段:");
X509Certificate cer = (X509Certificate)C;
System.out.println("版本号：" + cer.getVersion());
System.out.println("序列号：" + cer.getSerialNumber().toString());
System.out.println("颁发者：" + cer.getSubjectDN()); // System.out.println("颁发者唯一标识符: " + cer.getSubjectUniqueID().toString());
System.out.println("使用者：" + cer.getIssuerDN());
// System.out.println("使用者唯一标识符: " + cer.getIssuerUniqueID().toString());
System.out.println("有效期：from：" + cer.getNotBefore() + " to: " + cer.getNotAfter());
System.out.println("签发算法" + cer.getSigAlgName());
System.out.println("签发算法ID：" + cer.getSigAlgOID());
System.out.println("证书签名:" + cer.getSignature().toString());
byte [] sig = cer.getSigAlgParams();
PublicKey publicKey = cer.getPublicKey();
byte [] pkenc = publicKey.getEncoded();
System.out.println("解析出的公钥:" + Base64.getEncoder().encodeToString(pkenc));
System.out.println("公钥：");
for(int i = 0; i < pkenc.length; i++){
System.out.print(pkenc[i]);
}
} catch(Exception e){
e.printStackTrace();
}
}

两种方法都可以实现证书的解析，但是它们的依赖不同，没有配置相应的依赖，解析证书会失败，而且版本高的依赖貌似并不支持低版本依赖，有兴趣的可以研究是否不同依赖之间可以兼容。