Generate random certificates

Question

I am looking for a utility class that can generate random certificate strings for testing purposes. Any idea if there is one already implemented?

Answer 1

To add to solution given by martijno,

Instead of writing your own content signer, JCAContentSigner can be used to avoid mappings to AlgorithmIdentifier (i.e. OID).

JcaContentSignerBuilder takes algorithm names as defined here.

X509v3CertificateBuilder certBuilder = new X509v3CertificateBuilder(issuer, serialNumber, startDate, expiryDate, subject, SubjectPublicKeyInfo.getInstance(keyPair.getPublic().getEncoded()));
JcaContentSignerBuilder builder = new JcaContentSignerBuilder("SHA256withRSA");
ContentSigner signer = builder.build(keyPair.getPrivate());

byte[] certBytes = certBuilder.build(signer).getEncoded();
CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");
X509Certificate certificate = (X509Certificate)certificateFactory.generateCertificate(new ByteArrayInputStream(certBytes));