How to extract CN from X509Certificate in Java?

Here’s some code for the new non-deprecated BouncyCastle API. You’ll need both bcmail and bcprov distributions.

X509Certificate cert = ...;

X500Name x500name = new JcaX509CertificateHolder(cert).getSubject();
RDN cn = x500name.getRDNs(BCStyle.CN)[0];

return IETFUtils.valueToString(cn.getFirst().getValue());

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