Need Help for Code Changes to Upgrade from OpenSSL 1.0.2 to 3.0

[Matt Caswell]

On 25/10/2021 05:45, Paramashivaiah, Sunil wrote:
> Hi All,
> 
>          I need get APIs for accessing the members of  EVP_PKEY. Please 
> suggest APIs to get following members of EVP_PKEY
> 
> evpkey->type , evpkey->pkey.rsa , pubKey->pkey.ec->group.

EVP_PKEY_get_id() will get you the `evpkey->type` value. But note that 
in the provider world an external provider could add key types that are 
unknown to libcrypto. "EVP_PKEY_is_a" is a more future proof way to go.

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

E.g.

if (EVP_PKEY_is_a(pkey, "RSA")) ...;
if (EVP_PKEY_is_a(pkey, "EC")) ...;


The "evppkey->pkey.rsa" value can be obtained via EVP_PKEY_get0_RSA() 
but note that this is deprecated. You are encouraged to not use the RSA 
structure at all in 3.0 (all the functions that take an RSA structure 
are deprecated). So you should look at what you are trying to do with 
evpkey->pkey.rsa and refactor things to not need it. Why do you want this?

Similar comments apply to "pubkey->pkey.ec". You can get the EC_KEY 
object using EVP_PKEY_get0_EC_KEY() but this is deprecated. You can get 
the group from an EC_KEY using EC_KEY_get0_group() - but this is also 
deprecated. Instead you might consider getting the "group name" for the 
EC key which will tell you what curve is in use, e.g.

EVP_PKEY_get_utf8_string_param(pkey, OSSL_PKEY_PARAM_GROUP_NAME,
                                NULL, 0, &namesize);
name = OPENSSL_malloc(namesize + 1);
EVP_PKEY_get_utf8_string_param(pkey, OSSL_PKEY_PARAM_GROUP_NAME,
                                name, namesize + 1, 0);

https://www.openssl.org/docs/man3.0/man3/EVP_PKEY_get_utf8_string_param.html

Matt


> 
> Thanks and Regards,
> 
> Sunil
> 
> 
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