Tools/Options/PGP
There are two types of PGP encryption--symmetric encryption, also know as conventional encryption, and asymmetric or public key encryption. The former requires only a password to encrypt the text, while the latter requires correspondents create and exchange special cryptographic keys. Conventional encryption can be used without the necessity of enabling public key encryption.
PGP Public Key Encryption
Tick this option to enable public key encrytion.
Private Keyring
Use this field to tell QS where your PGP private keyring is located.
Public Keyring
Use this field to tell QS where your PGP public keyring is located.
Default Key
Select a key from your private keyring to be the default signing key. When signing messages the Secret Key Passphrase Dialog will auto-select this key, when it opens.
Mask PGP Version
Generally speaking, you want to mask the PGP version. This enhances security by making all versions appear the same--i.e. you are not partitioned by the version in use. Partitioning means you place yourself into a smaller group of users based on some identifiable characteristic(s). The goal is for your message to blend in with the highest number of messages as possible. Masking the version helps achieve this.
Cache Secret Key Passphrase
QS can hold your secret key passphrase in memory for a specified period of minutes. In this case if you sign with the secret key again within the given period, you will not be asked to enter the passphrase. It will be retrieved from the cache and used.