The Java program implements the operation of the certificate

1 Javaprogram reads certificate from certificate file

Import Java.io.*;import java.security.cert.*;p ublic class printcert{public static void Main (String args[]) throws Except ion{        certificatefactory cf=certificatefactory.getinstance ("the");        FileInputStream in=new FileInputStream ("My.cer");        Certificate c=cf.generatecertificate (in);        In.close ();        String s=c.tostring ();        Display certificate FileOutputStream fout=new fileoutputstream ("Tmp.txt");         BufferedWriter out= New BufferedWriter (New OutputStreamWriter (Fout));        Out.write (S,0,s.length ());         Out.close ();   }}  

2 Java programs read certificates directly from KeyStore

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 ());}    }  

3 Java program displays certificate specified information (full name/public key/signature, etc.)

Import java.io.*;import java.security.*;import java.security.cert.*;import java.math.*;p ublic class ShowCertInfo{ public static void Main (String args[]) throws exception{certificatefactory cf=certificatefactory.getinstance ("x.5        09 ");        FileInputStream in=new FileInputStream ("My.cer");        Java.security.cert.Certificate c=cf.generatecertificate (in);        In.close ();        X509Certificate t= (X509Certificate) C;        SYSTEM.OUT.PRINTLN ("Version number" +t.getversion ());        SYSTEM.OUT.PRINTLN ("Serial number" +t.getserialnumber (). toString (16));        System.out.println ("Full Name" +t.getsubjectdn ());        System.out.println ("Issuer full name n" +t.getissuerdn ());        SYSTEM.OUT.PRINTLN ("Valid Starting Date" +t.getnotbefore ());        SYSTEM.OUT.PRINTLN ("Valid until Date" +t.getnotafter ());        SYSTEM.OUT.PRINTLN ("Signature Algorithm" +t.getsigalgname ());        Byte[] Sig=t.getsignature ();        System.out.println ("Signature n" +new BigInteger (SIG). ToString (16));        PublicKey Pk=t.getpublickey ();   Byte[] pkenc=pk.getencoded ();     SYSTEM.OUT.PRINTLN ("Public Key");        for (int i=0;i< div= "" > System.out.print (pkenc[i]+ ","); }}}

The Java program implements the operation of the certificate