Checking certificates expiration dates in java keystore

Question

My java application uses a keystore file in which I have a certificate which is used in ssl connection with active directory server. What I have to do is to check its expiration date and prompt user if its close to expire. I have to do it while my application starts. My idea is to use external program: keytool to display info about certain certificate in the keystore and then do some parsing operations on a string which keytool outputs to find this validation date.

Here's the output of a specific keytool command:

Owner:
Issuer: CN=CPD Root CA, DC=cpd, DC=local<br>
Serial number: 39e8d1610002000000cb
<br>Valid from: Wed Feb 22 21:36:31 CET 2012 until: Thu Feb 21 21:36:31 CET 2013
Certificate fingerprints: <br>
         MD5:  82:46:8B:DB:BC:5C:64:21:84:BB:68:E3:4B:D4:35:70<br>
         SHA1: 35:52:CA:F2:11:66:1E:50:63:BC:53:A5:50:C1:F0:1E:62:81:BC:3F<br>
         Signature algorithm name: SHA1withRSA

Problem would be with parsing date since I can't be sure in which format it is displayed.

Is there any easier way to check expiration date of certificates included in java keystore file?

Answer 1

Thanks for the direction EJP, here is a block of what I came up with.

    try {
        KeyStore keystore = KeyStore.getInstance(KeyStore.getDefaultType());
        keystore.load(new FileInputStream("keystoreLocation"), "keystorePassword".toCharArray());
        Enumeration<String> aliases = keystore.aliases();
        while(aliases.hasMoreElements()){
            String alias = aliases.nextElement();
            if(keystore.getCertificate(alias).getType().equals("X.509")){
                System.out.println(alias + " expires " + ((X509Certificate) keystore.getCertificate(alias)).getNotAfter());
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
    }

Answer 2

Use the java.security.Keystore class to load the keystore and enumerate its contents, and check each certificate for expiry.