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pythondecodercsrpyopenssl

How to decode CSR using pyOpenssl


Get a string from the web page as it

-----BEGIN NEW CERTIFICATE REQUEST-----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-----END NEW CERTIFICATE REQUEST-----

How to decode it to plaintext like

Certificate information
Common name: www.xxx.net
Organization:xxx.net
Organizational unit:xxx.net
City/locality:bj
State/province:bj
Country:CN
Signature algorithm:SHA1
Key algorithm:RSA
Key size:1024

I know there is a third party pyopenssl, but not sure how to handle string buffer from web front-end. Or do you have any better idea? Thanks


Solution

  • You can load the certificate using OpenSSL.crypto.load_certificate_request() and then access the key and subject details from there, e.g.

    import OpenSSL.crypto
    from OpenSSL.crypto import load_certificate_request, FILETYPE_PEM
    
    csr = '''-----BEGIN NEW CERTIFICATE REQUEST-----
    MIIDPzCCAqgCAQAwZDELMAkGA1UEBhMCQ04xCzAJBgNVBAgTAmJqMQswCQYDVQQH
    EwJiajERMA8GA1UEChMIbXhjei5uZXQxETAPBgNVBAsTCG14Y3oubmV0MRUwEwYD
    VQQDEwx3d3cubXhjei5uZXQwgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJAoGBAMQ7
    an4v6pHRusBA0prMWXMWJCXY1AO1H0X8pvZj96T5GWg++JPCQE9guPgGwlD02U0B
    NDoEABeD1fwyKZ+JV5UFiOeSjO5sWrzIupdMI7hf34UaPNxHo6r4bLYEykw/Rnmb
    GKnNcD4QlPkypE+mLR4p0bnHZhe3lOlNtgd6NpXbAgMBAAGgggGZMBoGCisGAQQB
    gjcNAgMxDBYKNS4yLjM3OTAuMjB7BgorBgEEAYI3AgEOMW0wazAOBgNVHQ8BAf8E
    BAMCBPAwRAYJKoZIhvcNAQkPBDcwNTAOBggqhkiG9w0DAgICAIAwDgYIKoZIhvcN
    AwQCAgCAMAcGBSsOAwIHMAoGCCqGSIb3DQMHMBMGA1UdJQQMMAoGCCsGAQUFBwMB
    MIH9BgorBgEEAYI3DQICMYHuMIHrAgEBHloATQBpAGMAcgBvAHMAbwBmAHQAIABS
    AFMAQQAgAFMAQwBoAGEAbgBuAGUAbAAgAEMAcgB5AHAAdABvAGcAcgBhAHAAaABp
    AGMAIABQAHIAbwB2AGkAZABlAHIDgYkAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
    AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
    AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
    AAAAAAAAAAAAAAAAAAAAADANBgkqhkiG9w0BAQUFAAOBgQBIKHVhHb9FZdVLV4VZ
    9DK4aBSuYY//jlIpvsfMIdHXfAsuan7w7PH87asp1wdb6lD9snvLZix1UGK7VQg6
    wUFYNlMqJh1m7ITVvzhjdnx7EzCKkBXSxEom4mwbvSNvzqOKAWsDE0gvHQ9aCSby
    NFBQQMoW94LqrG/kuIQtjwVdZA==
    -----END NEW CERTIFICATE REQUEST-----'''
    
    req = load_certificate_request(FILETYPE_PEM, csr)
    key = req.get_pubkey()
    key_type = 'RSA' if key.type() == OpenSSL.crypto.TYPE_RSA else 'DSA'
    subject = req.get_subject()
    components = dict(subject.get_components())
    print "Common name:", components['CN']
    print "Organisation:", components['O']
    print "Orgainistional unit", components['OU']
    print "City/locality:", components['L']
    print "State/province:", components['ST']
    print "Country:", components['C']
    print "Signature algorithm:", '?'
    print "Key algorithm:", key_type
    print "Key size:", key.bits()
    

    Unfortunately I don't know how to get the signature algorithm.