SSL and "custom" EVP_KEY

Matt Caswell matt at
Fri Oct 29 15:11:31 UTC 2021

Hi Alex,

On 29/10/2021 14:32, Alex Dankow wrote:
> Hi OpenSSL team!
> I wrote a provider for Windows certificates and implemented "openssl ca".
> Now, I think it would be fun to see a HTTPS server using certificates 
> installed in Windows storage.

> Certificate is loaded using load_cert_pass (taken from apps.c) with 
> custom uri "wincert://11:22:33....",  private key is loaded with 
> load_key from apps.c too. It works, but ...
> When I use  SSL_CTX_use_PrivateKey(ctx, myprivk)  the key is declined. 
> OpenSSL compares strings and expects "rsaEncryption", and so on instead 
> of "MYKEY". Why ?

It's not entirely clear to me what you are attempting here. Are your 
certificates/keys stored in Windows storage standard RSA/ECDSA etc 
certs? Or are they using some custom algorithm?

If they are standard RSA/ECSDA certs then you should be using the 
correct standard algorithm names in you keymgmt etc and it should all 
"just work".

Unfortunately, in 3.0, libssl only supports standard algorithms. We have 
discussed a "pluggable" signature scheme mechanism which would enable 
plugging in arbitrary algorithms but it didn't make it for 3.0:

I'd still like to get back to that at some point but we don't have it 
yet. It should be entirely possible with the new provider architecture - 
and in fact we *did* add pluggable kex/kem support for libssl. But we 
just ran out of time with pluggable signatures.


> Maybe I'm missing something, but if you built a key management system, 
> sign interface, ciphers that allows key virtualization, why not go 
> further ? I'm ready to implement the encryption interface, but why 
> OpenSSL still care about key type name. In the new era of version 3, it 
> can check if the key provides necessary interfaces.
> --
> Alex Dankow

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