enable pkcs11 for server secret key material

[Daniel Kahn Gillmor]

Nikos writes on-list with a good suggestion:

I was thinking ways of how a memory leakage in mod_gnutls could have prevented revealing secrets such as the server's private key, and I think that this could be "easily" doable if mod_gnutls would support pkcs11 keys (from a quick glimpse I think it doesn't yet). If it would support it, then one could use a software security module such as ​lsm-pkcs11 and separate the private key operations from the server process. I put "easily" on quotes because unfortunately lsm-pkcs11 seem to be a dead project and more modern modules like ​softhsm don't use any isolation between the key operations and the calling process.

Nevertheless, I think it would be a good feature to have.

I also think this would be a useful feature.

[Nikos Mavrogiannopoulos]

There is a patch enabling this feature.

​https://github.com/nmav/mod_gnutls/commit/031acac9c6541034777f8917633164b51f6bd10a

[Thomas Klute]

Implemented in version 0.7, thanks to Nikos for the patch!