[Cryptography-dev] Extracting pub key from a csr

[Alex Gaynor]

You're getting back the public key object for that CSR. When you say
you want the "public key itself" what do you mean?

Alex

On Thu, Aug 29, 2024 at 10:54 PM Robert Moskowitz <rgm at htt-consult.com> wrote:
>
> I have a csr with an eddsa25519 key:
>
> -----BEGIN CERTIFICATE REQUEST-----
> MIGPMEMCAQAwEDEOMAwGA1UEBRMFeDEyMjQwKjAFBgMrZXADIQAqLOv73gF8OMT9
> dvXIai0HOzyoT0kWkwziuPObnb+PbaAAMAUGAytlcANBAMbkfr344AGb2NHMJOk7
> hUdknmKY3XOrAKITLbE0X5NiSxfsZ8ovLG4SnmIEE86t5pWfaPAFhJ8t+jMGJUzQ
> XgM=
> -----END CERTIFICATE REQUEST-----
>
> I want the Pbkey of
>
>          Subject Public Key Info:
>              Public Key Algorithm: ED25519
>                  ED25519 Public-Key:
>                  pub:
>                      e7:3f:5c:a1:b7:78:8a:75:e4:7b:91:4c:0c:1c:48:
>                      d7:f8:06:c1:f1:9d:58:b0:4d:c9:48:7f:3d:1d:bc:
>                      ac:16
>
> I am following
>
> https://cryptography.io/en/3.4.7/x509/reference.html#loading-certificate-signing-requests
> and
> https://cryptography.io/en/3.4.7/x509/reference.html#x-509-csr-certificate-signing-request-builder-object
>
> I tried the following to get the key:
>
> from cryptography.hazmat.primitives import serialization
> from cryptography.hazmat.primitives.asymmetric import ed25519
> from cryptography import x509
> from cryptography.x509.oid import NameOID
> from cryptography.hazmat.primitives.serialization import load_pem_private_key
>
> with open(uacsr, "rb") as f:
>      pem_req_data = f.read()
>      csr = x509.load_pem_x509_csr(pem_req_data)
> csr_pbkey = csr.public_key()
> print(csr_pbkey)
>
> and get:
>
> <cryptography.hazmat.backends.openssl.ed25519._Ed25519PublicKey object at 0x7f513f0d39d0>
>
> not the public key itself.
>
> What am I missing here?
>
> thanks
>
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