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GPG Cheatsheet
GPG stands for GNU Privacy Guard and it is vital tool for everyone who wants to protect the email and files. Like it's inspiration PGP, GPG uses public-key cryptography where each user owns two keys: for decryption (public key) and for encryption (private key).
This cheatsheet is for quick reference and gives a brief description of that could be done with this security tool.
Keys management
GPG has several switches that allows to generate a public-private keypar, revoke and delete keys. The viewing public and private keys are also supported.
Generate key pair
To generate a public-private key pair in the GPG keyring use the –gen-key switch. The below command will prompt for some details such the key-type, key-size, user ID to identify the key and the time period over which the generated key will be valid:
gpg --gen-key
Revoke keys
In case if the secret key has been stolen, an existing key could be revoked with –gen-revoke switch. To be able to do this, is is needed for a secret key:
gpg --gen-revoke
Delete keys
The below commands are used to delete public and private keys from GPG keyring:
gpg --delete-key KeyID
gpg --delete-secret-key KeyID
gpg --delete-secret-and-public-key KeyID
View keys
To view all types of keys, issue the command:
gpg --list-key
gpg --list-public-keys
gpg --list-secret-keys
Keys manipulations
GPG allows several key manipulation functions such importing and exporting the keys. Sending and receiving keys from server are also supported.
Export a private key to a file
gpg --export-secret-key -a > file.out
Export a public key in a file
gpg --export --armor KeyID > file.out
Import a private key from a file
gpg --import --allow-secret-key-import file.in
Import a public key from a file
gpg --import file.in
Send a public key to a server
gpg --keyserver dbma.keyserver.ca --send-key KeyID
Get a Key from a server
gpg --keyserver dbma.keyserver.ca --recv-keys KeyID
Cryptographic options
GPG allows file encryption and decryption. Another option is support for file signing that makes this program an alternative to PGP.