java加密解密与数字证书的操作

1 Java程序实现密钥库的维护

1.1 Java程序列出密钥库所有条目

import java.util.*;

import java.io.*;

import java.security.*;

public class ShowAlias{

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

String pass="080302";

String name=".keystore";

FileInputStream in=new FileInputStream(name);

KeyStore ks=KeyStore.getInstance("JKS");

ks.load(in,pass.toCharArray());

Enumeratione=ks.aliases( );

while( e.hasMoreElements()) {

System.out.println(e.nextElement());

}

}

}

1.2 Java程序修改密钥库口令

import java.io.*;

import java.security.*;

public class SetStorePass{

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

char[ ] oldpass="080302".toCharArray();

char[ ] newpass="123456".toCharArray();

String name=".keystore";

FileInputStream in=new FileInputStream(name);

KeyStore ks=KeyStore.getInstance("JKS");

ks.load(in,oldpass);

in.close();

FileOutputStream output=new FileOutputStream(name);

ks.store(output,newpass);

output.close();

}

}

1.3 Java程序修改密钥库条目的口令及添加条目

package test;

import java.io.*;

import java.security.*;

import java.security.cert.Certificate;

public class SetKeyPass{

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

//读取相关参数

String name=".keystore";

String alias="mykey";

char[ ] storepass="123456".toCharArray();

char[ ] oldkeypass="080302".toCharArray();

char[ ] newkeypass="123456".toCharArray();

//获取密钥库.keystore的KeyStore对象，并加载密钥库

FileInputStream in=new FileInputStream(name);

KeyStore ks=KeyStore.getInstance("JKS");

ks.load(in,storepass);

//获取别名对应的条目的证书链

Certificate[ ] cchain=ks.getCertificateChain(alias);

//读取别名对应的条目的私钥

PrivateKey pk=(PrivateKey)ks.getKey(alias,oldkeypass);

//向密钥库中添加新的条目

ks.setKeyEntry(alias,pk,newkeypass,cchain);

in.close();

//将KeyStore对象内容写入新文件

FileOutputStream output=new FileOutputStream("333");

ks.store(output,storepass);

output.close();

}

}

1.4 Java程序检验别名及删除条目

package test;

import java.io.*;

import java.security.*;

public class DeleteAlias{

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

String pass = "123456";

String name = ".keystore";

String alias = "mykey";

FileInputStream in=new FileInputStream(name);

KeyStore ks=KeyStore.getInstance("JKS");

ks.load(in,pass.toCharArray());

if (ks.containsAlias(alias)){

ks.deleteEntry(alias);

FileOutputStream output=new FileOutputStream(name);

ks.store(output,pass.toCharArray());

System.out.println("Alias "+alias+" deleted");

}else{

System.out.println("Alias not exist");

}

}

}

2 Java程序读取证书和显示证书指定信息

2.1 Java程序从证书文件读取证书

import java.io.*;

import java.security.cert.*;

public class PrintCert{

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

CertificateFactory cf=CertificateFactory.getInstance("X.509");

FileInputStream in=new FileInputStream("my.cer");

Certificate c=cf.generateCertificate(in);

in.close();

String s=c.toString( );

// 显示证书

FileOutputStream fout=new FileOutputStream("tmp.txt");

BufferedWriter out= new BufferedWriter(new OutputStreamWriter(fout));

out.write(s,0,s.length( ));

out.close();

}

}

2.2 Java程序从密钥库直接读取证书

import java.io.*;

import java.security.*;

import java.security.cert.Certificate;

public class PrintCert2{

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

String pass="080302";

String alias="mykey";

String name=".keystore";

FileInputStream in=new FileInputStream(name);

KeyStore ks=KeyStore.getInstance("JKS");

ks.load(in,pass.toCharArray());

Certificate c=ks.getCertificate(alias);

in.close();

System.out.println(c.toString( ));

}

}

2.3 Java程序显示证书指定信息（全名/公钥/签名等）

import java.io.*;

import java.security.*;

import java.security.cert.*;

import java.math.*;

public class ShowCertInfo{

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

CertificateFactory cf=CertificateFactory.getInstance("X.509");

FileInputStream in=new FileInputStream("my.cer");

java.security.cert.Certificate c=cf.generateCertificate(in);

in.close();

X509Certificate t=(X509Certificate) c;

System.out.println("版本号 "+t.getVersion());

System.out.println("序列号 "+t.getSerialNumber().toString(16));

System.out.println("全名 "+t.getSubjectDN());

System.out.println("签发者全名n"+t.getIssuerDN());

System.out.println("有效期起始日 "+t.getNotBefore());

System.out.println("有效期截至日 "+t.getNotAfter());

System.out.println("签名算法 "+t.getSigAlgName());

byte[] sig=t.getSignature();

System.out.println("签名n"+new BigInteger(sig).toString(16));

PublicKey pk=t.getPublicKey();

byte[ ] pkenc=pk.getEncoded();

System.out.println("公钥");

for(int i=0;i< div="">

System.out.print(pkenc[i]+",");

}

}

}