JAVA对数字证书的常用操作(转载)

一：需要包含的包   

1import  java.security. * ;
2     import  java.io. * ;
3     import  java.util. * ;
4     import  java.security. * ;
5     import  java.security.cert. * ;
6     import  sun.security.x509. * 
7     import  java.security.cert.Certificate;
8     import  java.security.cert.CertificateFactory;

二：从文件中读取证书
    用keytool将.keystore中的证书写入文件中，然后从该文件中读取证书信息

1CertificateFactory cf = CertificateFactory.getInstance( " X.509 " );
2    FileInputStream in = new  FileInputStream( " out.csr " );
3    Certificate c = cf.generateCertificate(in);
4    String s = c.toString();

三：从密钥库中直接读取证书

1String pass = " 123456 " ;
2    FileInputStream in = new  FileInputStream( " .keystore " );
3    KeyStore ks = KeyStore.getInstance( " JKS " );
4    ks.load(in,pass.toCharArray());
5    java.security.cert.Certificate c = ks.getCertificate(alias); // alias为 
6   条目的别名

四：JAVA程序中显示证书指定信息

1System.out.println( " 输出证书信息:\n " + c.toString());
2    System.out.println( " 版本号: " + t.getVersion());
3    System.out.println( " 序列号: " + t.getSerialNumber().toString( 16 ));
4    System.out.println( " 主体名： " + t.getSubjectDN());
5    System.out.println( " 签发者： " + t.getIssuerDN());
6    System.out.println( " 有效期： " + t.getNotBefore());
7    System.out.println( " 签名算法： " + t.getSigAlgName());
8     byte  [] sig = t.getSignature(); // 签名值  
9     PublicKey pk = t.getPublicKey();
10     byte  [] pkenc = pk.getEncoded();  
11    System.out.println( " 公钥 " );
12     for ( int  i = 0 ;i < pkenc.length;i ++ )System.out.print(pkenc[i] + " , " );

五：JAVA程序列出密钥库所有条目

1String pass = " 123456 " ;
2    FileInputStream in = new  FileInputStream( " .keystore " );
3    KeyStore ks = KeyStore.getInstance( " JKS " );
4    ks.load(in,pass.toCharArray());
5    Enumeration e = ks.aliases();
6     while (e.hasMoreElements())
7    java.security.cert.Certificate c = ks.getCertificate((String)e.nextElement());

六：JAVA程序修改密钥库口令

1String oldpass = " 123456 " ;
2    String newpass = " 654321 " ;
3    FileInputStream in = new  FileInputStream( " .keystore " );
4    KeyStore ks = KeyStore.getInstance( " JKS " );
5    ks.load(in,oldpass.toCharArray());
6    in.close();
7    FileOutputStream output = new  FileOutputStream( " .keystore " );
8    ks.store(output,newpass.toCharArray());
9    output.close();

七：JAVA程序修改密钥库条目的口令及添加条目

1FileInputStream in = new  FileInputStream( " .keystore " );
2    KeyStore ks = KeyStore.getInstance( " JKS " );
3    ks.load(in,storepass.toCharArray());
4    Certificate [] cchain = ks.getCertificate(alias);获取别名对应条目的证书链
5    PrivateKey pk = (PrivateKey)ks.getKey(alias,oldkeypass.toCharArray());获取别名对应条目的私钥
6    ks.setKeyEntry(alias,pk,newkeypass.toCharArray(),cchain);向密钥库中添加条目

    第一个参数指定所添加条目的别名，假如使用已存在别名将覆盖已存在条目，使用新别名将增加一个新条目，第二个参数为条目的私钥，第三个为设置的新口令，第四个为该私钥的公钥的证书链

1FileOutputStream output=new FileOutputStream("another");
2    ks.store(output,storepass.toCharArray())将keystore对象内容写入新文件

八：JAVA程序检验别名和删除条目

1FileInputStream in = new  FileInputStream( " .keystore " );
2    KeyStore ks = KeyStore.getInstance( " JKS " );
3    ks.load(in,storepass.toCharArray());
4    ks.containsAlias( " sage " );检验条目是否在密钥库中，存在返回true
5    ks.deleteEntry( " sage " );删除别名对应的条目
6    FileOutputStream output = new  FileOutputStream( " .keystore " );
7    ks.store(output,storepass.toCharArray())将keystore对象内容写入文件,条目删除成功

九：JAVA程序签发数字证书

（1）从密钥库中读取CA的证书

1FileInputStream in = new  FileInputStream( " .keystore " );
2    KeyStore ks = KeyStore.getInstance( " JKS " );
3    ks.load(in,storepass.toCharArray());
4    java.security.cert.Certificate c1 = ks.getCertificate( " caroot " );

（2）从密钥库中读取CA的私钥
    

PrivateKey caprk = (PrivateKey)ks.getKey(alias,cakeypass.toCharArray());

 （3）从CA的证书中提取签发者的信息   

1byte [] encod1 = c1.getEncoded();    提取CA证书的编码
2    X509CertImpl cimp1 = new  X509CertImpl(encod1);  用该编码创建X509CertImpl类型对象
3    X509CertInfo cinfo1 = (X509CertInfo)cimp1.get(X509CertImpl.NAME + " . " + X509CertImpl.INFO);  获取X509CertInfo对象
4    X500Name issuer = (X500Name)cinfo1.get(X509CertInfo.SUBJECT + " . " + CertificateIssuerName.DN_NAME); 获取X509Name类型的签发者信息

    （4）获取待签发的证书   

1CertificateFactory cf = CertificateFactory.getInstance( " X.509 " );
2    FileInputStream in2 = new  FileInputStream( " user.csr " );
3    java.security.cert.Certificate c2 = cf.generateCertificate(in);

    （5）从待签发的证书中提取证书信息  

1byte  [] encod2 = c2.getEncoded();
2    X509CertImpl cimp2 = new  X509CertImpl(encod2);  用该编码创建X509CertImpl类型对象
3    X509CertInfo cinfo2 = (X509CertInfo)cimp2.get(X509CertImpl.NAME + " . " + X509CertImpl.INFO);  获取X509CertInfo对象

    （6）设置新证书有效期   

1Date begindate = new  Date(); 获取当前时间
2    Date enddate = new  Date(begindate.getTime() + 3000 * 24 * 60 * 60 * 1000L ); 有效期为3000天
3    CertificateValidity cv = new  CertificateValidity(begindate,enddate); 创建对象
4    cinfo2.set(X509CertInfo.VALIDITY,cv);  设置有效期

    （7）设置新证书序列号

1int  sn = ( int )(begindate.getTime() / 1000 );    以当前时间为序列号
2    CertificateSerialNumber csn = new  CertificateSerialNumber(sn);
3    cinfo2.set(X509CertInfo.SERIAL_NUMBER,csn);

    （8）设置新证书签发者  

cinfo2.set(X509CertInfo.ISSUER+"."+CertificateIssuerName.DN_NAME,issuer);应用第三步的结果

    （9）设置新证书签名算法信息

1AlgorithmId algorithm=new AlgorithmId(AlgorithmId.md5WithRSAEncryption_oid);
2    cinfo2.set(CertificateAlgorithmId.NAME+"."+CertificateAlgorithmId.ALGORITHM,algorithm);

    （10）创建证书并使用CA的私钥对其签名

1X509CertImpl newcert=new X509CertImpl(cinfo2);
2    newcert.sign(caprk,"MD5WithRSA"); 使用CA私钥对其签名

    （11）将新证书写入密钥库   

1ks.setCertificateEntry( " lf_signed " ,newcert);
2    FileOutputStream out = new  FileOutputStream( " newstore " );
3    ks.store(out, " newpass " .toCharArray());  这里是写入了新的密钥库，也可以使用第七条来增加条目

十：数字证书的检验

（1）验证证书的有效期
 （a）获取X509Certificate类型对象

1CertificateFactory cf = CertificateFactory.getInstance( " X.509 " );
2    FileInputStream in1 = new  FileInputStream( " aa.crt " );
3  java.security.cert.Certificate  c1 = cf.generateCertificate(in1);
4 X509Certificate t = (X509Certificate)c1;
5  in2.close();

        （b）获取日期

Date TimeNow=new Date();

 （c）检验有效性

1try {
2    t.checkValidity(TimeNow);
3           System.out.println( " OK " );
4 } catch (CertificateExpiredException e) {   // 过期 
5     System.out.println( " Expired " );
6    System.out.println(e.getMessage());
7 } catch ((CertificateNotYetValidException e) {  // 尚未生效 
8     System.out.println( " Too early " );
9    System.out.println(e.getMessage());} 

     （2）验证证书签名的有效性

 （a）获取CA证书       

1CertificateFactory cf = CertificateFactory.getInstance( " X.509 " ); FileInputStream in2 = new  FileInputStream( " caroot.crt " );
2 java.security.cert.Certificate  cac = cf.generateCertificate(in2);
3 in2.close();

 （c）获取CA的公钥

  PublicKey pbk=cac.getPublicKey();
 （b）获取待检验的证书（上步已经获取了，就是C1）
 （c）检验证书
        

1boolean  pass = false ;
2          try {
3      c1.verify(pbk);
4             pass = true ;
5         } catch (Exception e) {
6             pass = false ;
7             System.out.println(e);
8  }  

转载地址：http://www.blogjava.net/ctguzhupan/archive/2006/04/26/63177.html