GnuPG 2.1.x and 2.2.x keyring formats

[Jeffrey Stedfast]

Hi all,

I know that starting with GnuPG 2.1.x, the use of pubring.gpg and secring.gpg changed and gpg now uses private-keys-v1.d/ to store keys (or is it only private keys?).

I guess I have a couple of questions:

1. What is the file format of the *.key files in the private-keys-v1.d directory?
2. How are these files named? Does the file name correspond with a fingerprint / key id?
3. Does gpg still use pubring.gpg?

I'm asking these questions because I have a C# email library that uses Bouncy Castle for OpenPGP support that I'm trying to make interoperable with GnuPG as much as I can.

Any information you can share with me so that I can make my library work with GnuPG 2.2 would be fantastic.

Thanks!

Jeff