JAVA对数字证书的经常使用操做(转载)

一：须要包含的包 html

import  java.security. * ; import  java.io. * ; import  java.util. * ; import  java.security. * ; import  java.security.cert. * ; import  sun.security.x509. * 
     import java.security.cert.Certificate; 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，而后从该文件中读取证书信息 java

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

三：从密钥库中直接读取证书
算法

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

四：JAVA程序中显示证书指定信息
编码

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

五：JAVA程序列出密钥库全部条目
url

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

六：JAVA程序修改密钥库口令
spa

String oldpass = " 123456 " ; String newpass = " 654321 " ; FileInputStream in = new  FileInputStream( " .keystore " ); KeyStore ks = KeyStore.getInstance( " JKS " ); ks.load(in,oldpass.toCharArray()); in.close(); FileOutputStream output = new  FileOutputStream( " .keystore " ); ks.store(output,newpass.toCharArray()); output.close();

七：JAVA程序修改密钥库条目的口令及添加条目 .net

FileInputStream in = new  FileInputStream( " .keystore " ); KeyStore ks = KeyStore.getInstance( " JKS " ); ks.load(in,storepass.toCharArray()); Certificate [] cchain = ks.getCertificate(alias);获取别名对应条目的证书链 PrivateKey pk = (PrivateKey)ks.getKey(alias,oldkeypass.toCharArray());获取别名对应条目的私钥 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，使用新别名将增长一个新条目，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code

FileOutputStream output=new FileOutputStream("another"); 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
htm

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

九：JAVA程序签发数字证书对象

（1）从密钥库中读取CA的证书

FileInputStream in = new  FileInputStream( " .keystore " ); KeyStore ks = KeyStore.getInstance( " JKS " ); ks.load(in,storepass.toCharArray()); 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

byte [] encod1 = c1.getEncoded(); 提取CA证书的编码 X509CertImpl cimp1 = new X509CertImpl(encod1); 用该编码建立X509CertImpl类型对象 X509CertInfo cinfo1 = (X509CertInfo)cimp1.get(X509CertImpl.NAME + " . " + X509CertImpl.INFO); 获取X509CertInfo对象 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

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

（5）从待签发的证书中提取证书信息

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

（6）设置新证书有效期

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

（7）设置新证书序列号

int  sn = ( int )(begindate.getTime() / 1000 ); 以当前时间为序列号 CertificateSerialNumber csn = new CertificateSerialNumber(sn); 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

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

（10）建立证书并使用CA的私钥对其签名

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

（11）将新证书写入密钥库

ks.setCertificateEntry( " lf_signed " ,newcert); FileOutputStream out = new  FileOutputStream( " newstore " ); ks.store(out, " newpass " .toCharArray());  这里是写入了新的密钥库，也能够使用第七条来增长条目

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

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

（b）获取日期

Date TimeNow=new Date();

（c）检验有效性

try { t.checkValidity(TimeNow); System.out.println( " OK " ); } catch (CertificateExpiredException e) {   // 过时 
     System.out.println( " Expired " ); System.out.println(e.getMessage()); } catch ((CertificateNotYetValidException e) {  // 还没有生效 
     System.out.println( " Too early " ); System.out.println(e.getMessage());}

（2）验证证书签名的有效性

（a）获取CA证书

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

boolean  pass = false ; try { c1.verify(pbk); pass = true ; } catch (Exception e) { pass = false ; System.out.println(e); }

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