EVP_PKEY_get_raw_public_key fails with OpenSSL 3.0

[Matt Caswell]

On 11/11/2022 12:41, fus at plutonium24.de wrote:
> 
> My apologies. I tested the code you supplied and of course it also fails 
> with 1.1.1. The code was changed without my knowledge when updating to 
> 3.0 and the version that was working used the deprecated 
> "EC_POINT_point2oct". During my test I missed this.
> 
> Concerning the questions James akesd: I extract the key from an X509 
> certificate (with X509_get0_pubkey). And as you suggested I just need 
> the bytes of the public EC point. As a reference to which I want to 
> compare this data I only have the raw public key and a proprietarily 
> encoded curve id which I also check.
> 
> 
> I'd like to come back to the question : how can I get the raw public 
> key^without using deprecated functionality?
> 
> Frank
> 

Probably calling EVP_PKEY_get_octet_string_param() and asking for the 
parameter OSSL_PKEY_PARAM_ENCODED_PUBLIC_KEY should do it. See these man 
pages:

https://www.openssl.org/docs/man3.0/man3/EVP_PKEY_get_params.html

https://www.openssl.org/docs/man3.0/man7/EVP_PKEY-EC.html

Matt