This post will cover the basics when it comes to secure communications on the internet, the lingo / terms used, between clients and servers.
PGP - Pretty Good Privacy
Encrypt data / messages by ways of private / public keys. Verify the messenger as well as the integrity of the data. Sender / Receiver. Signing / encrypting / decrypting
$HOME/.gnupg - This is the default home directory w
$HOME/.gnugpg/gpg-agent.conf - configuration file for gpg-agent [backup]
$HOME/.gnugpg/gpg.conf - default configurations for gpg. [backup]
$HOME/.gnugpg/private-keys-v1.d/ - directory that gpg-agent uses to store private keys [backup]
$HOME/.gnugpg/secring.gpg - [superseded by private-keys-v1.d]
$HOME/.gnugpg/pubring.kbx - public key ring. This a database file storing the certificates as well as meta information. [backup]
$HOME/.gnugpg/pubring.gpg - [superseded by pubring.kbx]
$HOME/.gnugpg/random_seed - A file used to preserve the state of the internal random pool.
$HOME/.gnugpg/S.gpg-agent - socket that gpg-agent uses to communicate
$HOME/.gnugpg/trustdb.gpg - the trust database
trustlist.txt - This is the global list of trusted keys [backup]
Note some of the files have lock files associated with them when the files are being modified.
A key ring is a file which contains multiple public keys of certificate authority (CA). A key ring is a file which is necessary for Secure Sockets Layer (SSL) connection over the web. It is securely stored on the server which hosts the website. It contains the public/private key pair for the particular website. It also contains the public/private key pairs from various certificate authorities and the trusted root certificate for the various certification authorities. An entity or website administrator has to send a certificate signing request (CSR) to the CA. The CA then returns a signed certificate to the entity. This certificate received from the CA has to be stored in the key ring.