How to parse certificate_policies_value

[dwabisch]

Hi together,

I am trying to get the OID from my certPolicy. I load a cert and got the policy like this:

certPolicy = cert.certificate_policies_value

When I print it out I get this one: <asn1crypto.x509.CertificatePolicies 140403662836112 b'0C0A\x06\x0b+\x06\x01\x04\x01\x81\x9d{\x04\x01\x010200\x06\x08+\x06\x01\x05\x05\x07\x02\x01\x16$https://www.test.com'>

But how can I get only the OID out of the variable (certPolicy) ?

[MatthiasValvekens]

Assuming there's only one policy (warning: untested):

cert.certificate_policies_value[0]['policy_identifier'].dotted

EDIT: here's the definition of the CertificatePolicies type: https://github.com/wbond/asn1crypto/blob/fad689f2072e405317436c8bf7f6609ba183a060/asn1crypto/x509.py#L1642-L1643.

[dwabisch]

Thanks for the fast reply!

I tried it like this before and got always the error:

cert.certificate_policies_value[0]['policy_identifier'].dotted

TypeError: 'NoneType' object is not subscriptable

[MatthiasValvekens]

That's what you would get if the cert doesn't have the cert policies extension at all. Are you sure that this is the same certificate object as the one in your original post? If so, try these in order to see which one fails:

cert.certificate_policies_value[0]
cert.certificate_policies_value[0]['policy_identifier']
cert.certificate_policies_value[0]['policy_identifier'].dotted

[dwabisch]

Thank you very much! This was the problem. My first example does not have any cert policies. I just tried it with an other cert, now it works.