X509 certificate CSR DN parsing

Question

I'm having a problem with X.509 certificate DN parsing. The CSR generated is of the form:

/C=/ST=/L=/O=/OU=/CN=

The signed certificate issued by the CA is of the form:

C=USA, ST=NJ, L=test, O=Google, OU=Adwords, CN=test

I need a utility class in Java, preferably something standard that will take either of these notations and canonicalize the DN to a standard format so I can compare the CSR and X.509 certificate data to determine if the DN's match.

Any help would be appreciated.

Answer 1

For parsing the X509 Certificate issued by the CA, you can use the following java api: java.security.cert.X509Certificate

Code snippet:

    extractX509DN(X509Certificate cert) {
        String domainName;
        domainName = cert.getSubjectDN().getName();
    }

Likewise, you can use the other methods in the api to extract details of the certificate you need.

For parsing the raw CSR, you can use the apis provided by BouncyCastle. I found a handy tutorial which you could probably use to understand the method involved in parsing a CSR:

Parse CSR Code Snippet

Go through the above link and understand the following function:

    public CSRInfo parseCSR (String csr);

Your answer lies in line number 76 of the above code snippet.