Add dump_publickey as a complement for dump_privatekey

[Adi Roiban]

The pyOpenSSL API already has a crypto.dump_privatekey .

It would be nice to also have a dump_publickey method.

I will attach a branch with an initial implementation of this method (only PEM format).

If this change is wanted, I can improve the branch.

Cheers

[Adi Roiban (adiroiban)]

Hi,

Do you have any comments about how you would like to bug solved?

I reported this bug while I was looking for a way to generate SSH public and private keys from Python without external calls to openssh-keygen or openssl.

My first stop was pyOpenSSL since I knew that OpenSSH is using openssl.

Later I found the code from twisted.conch.ssh.key and used the Key class to generate my public and private keys in the OpenSSH format.

I am willing to continue implementing the crypto.dump_privatekey API, but after learning more about pyOpenSSL I was thinking that it would be better to export the key elements in PKey and the dump_privakekey could use them to dump the key in various formats.

[Jean-Paul Calderone (exarkun)]

I think adding a dump_publickey API is fine. None of these APIs is what I'd call ideal. Instead they're simple to implement and maintain without adding too much extra functionality on top of OpenSSL.