Please help: Getting publicKey from certificate

Question

Hi,
I have created a certificate using keytool, and now I'm trying to extract a publicKey object from it via Java code.
I generated the certificate using the following commands:
.keytool -genkey -keystore test -alias abc123 -keyalg RSA -storepass xxxxxx
keytool -export -file tester.der -keystore test -alias abc123 -storepass xxxxxxI'm trying the following code:
KeyStore ks1 = KeyStore.getInstance ( "JKS");
ks1.load( (InputStream)(new FileInputStream( "C:\\Program Files\\Java\\jdk1.5.0_01\\bin\\tester.der" )), "xxxxxx".toCharArray() );
          Certificate c = ks1.getCertificate( "abc123" );
          PublicKey p = c.getPublicKey();where, xxxxxx is the passwod, abc123 is the alias I used to create the key store, and tester.der is the certificate file.
I'm getting the following error:
Exception in thread "main" java.io.IOException: Invalid keystore format
     at sun.security.provider.JavaKeyStore.engineLoad(JavaKeyStore.java:632)
     at java.security.KeyStore.load(KeyStore.java:1150)
I guess that the problem is related to the fact that in the getInstance() call, I used "JKS"? But if his is indeed the problem, with which string should I replace it?
Please help!!
thanks,
Amir

Answer 1

Thanks,
but... the key store file itself should NOT be at the
client side, only the certificate file!
So, if the client wants to load the public key via
the certificate, how can he do that? Isn't
there a way to load a public key from the certificate
itself into a Java publicKey object and not
from the key store file??
thanks a lot in advance,
AmirSo use a certificate factory to load the certificate and extract the public key. For excample
    CertificateFactory cf = CertificateFactory.getInstance("X.509");
            Certificate cert = cf.generateCertificate(new FileInputStream(certificateFile));
            java.security.interfaces.RSAPublicKey pk = (java.security.interfaces.RSAPublicKey)cert.getPublicKey();           
            System.out.println(pk.getAlgorithm());
            System.out.println(pk.getPublicExponent());
            System.out.println(pk.getModulus());