valisign.java

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import java.io.*;
import java.security.*;
import java.security.cert.*;
import java.security.cert.Certificate;
import java.util.*;

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

          Certificate[] certpath=new Certificate[args.length-1];
          CertificateFactory cf = CertificateFactory.getInstance("X.509");
          int i;
          for (i=0;i<args.length-1;i++){
		  FileInputStream in=new FileInputStream(args[i]);
                  certpath[i]=cf.generateCertificate(in);
          }
          // RootCert
          FileInputStream in=new FileInputStream(args[i]);
          Certificate trust=cf.generateCertificate(in);

	  boolean pass=false;	  
          String reason="";
          for(i=0;i<certpath.length;i++){
          	try{
                     PublicKey pbk;
                     if(i==certpath.length-1){
                           pbk =trust.getPublicKey();
                     }
                     else{
                           pbk = certpath[i+1].getPublicKey();
                     }
                     certpath[i].verify(pbk);
                     pass=true;
                }
                catch (Exception e){ 
                     pass=false;
                     reason+=i+"  "+e.toString( );
		     break;
                }
	  }

          if(pass){
                 System.out.println("signature verification OK");
	  }
	  else{
                 System.out.println("signature verification failed in "+reason);
	  }
   }  
}