Hello everyone. Need some help with crypto routines in Java.
Given a PKCS#7 signature, I want to verify all certificates it contains against a trusted store. I assume that all certificates contained in signature are in the correct order to form a valid certificate path (or chain, whatever), so that
- topmost (#0) is a signing certificate;
- next one (#1) is an intermediate certificate, used to sign #0;
- next one (#2) is another intermediate certificate, used to sign #1;
- and so on.
The last certificate (#N) is signed by CA.
That's what I've managed to hack so far:
// Exception handling skipped for readability
//byte[] signature = ...
pkcs7 = new PKCS7(signature); // `sun.security.pkcs.PKCS7;`
// *** Checking some PKCS#7 parameters here
X509Certificate prevCert = null; // Previous certificate we've found
X509Certificate[] certs = pkcs7.getCertificates(); // `java.security.cert.X509Certificate`
for (int i = 0; i < certs.length; i++) {
// *** Checking certificate validity period here
if (cert != null) {
// Verify previous certificate in chain against this one
prevCert.verify(certs[i].getPublicKey());
}
prevCert = certs[i];
}
//String keyStorePath = ...
KeyStore keyStore = KeyStore.getInstance("JKS"); // `java.security.KeyStore`
keyStore.load(new FileInputStream(keyStorePath), null);
// Get trusted VeriSign class 1 certificate
Certificate caCert = keyStore.getCertificate("verisignclass1ca"); // `java.security.cert.Certificate`
// Verify last certificate against trusted certificate
cert.verify(caCert.getPublicKey());
So the question is -- how can this be done using standard Java classes like CertPath
and friends? I have a strong feeling I'm re-inventing a bicycle. Or, if someone has an example with BouncyCastle library, that would also be fine.
Bonus question: how to verify a certificate against a trusted store so that root certificate is selected automatically?