GNU gpg#

Generate keyfile in a particular location#

gpg --homedir /home/fubar/gpgkeytest --gen-key
# A dialog will walk you through the remaining inputs 
#If the process seems to hang during the 'gaining entropy phase', open another shell and run this command until the process completes:
dd if=/dev/sda of=/dev/zero
#(this command reads from your hard drive and discards the output, because writing to /dev/zero will does nothing.)

#use expert mode to obtain more control over key construct:
gpg --homedir /home/fubar/gpgkeytestalt --expert --gen-key
#the ubuntu/debian variation
gpg --homedir /home/fubar/gpgtesting --expert --full-gen-key

List all keys in the keystore:#

gpg -v --list-keys

List all components of a particular key (including subkey IDs):#

gpg --edit-key "84840EA6B62C743BDC4108EAF939BDEF01DCCF89"

Dump the key certificate to screen:#

gpg -a --export "keyid" | gpg --list-packets --verbose

Export public and private keys:#

#public
gpg -a --export <keyid>
#private
gpg --export-secret-key -a <keyid>
#NOTE when using multiple "homedir"s for key generation and administration, gpg-agent may cache passphrases such that when you try to export keys it is basically ignoring the key that you are trying to paste in response to a prompt (using the wrong value that it has cached instead). To fix that in Ubuntu, do the following (clears the cache):
gpgconf --reload gpg-agent

Import a private key and mark trust as Ultimate:#

gpg --import asciiarmoredprivatekey.asc
#for above, you will be prompted for the key passphrase
gpg --edit-key <keyid> trust quit
#above will invoke interactive prompt for changing trust level
#choose '5 = I trust ultimately', after which you will be prompted to confirm decision

NOTE that gpg is capable of supporting symmetric encryption:#

#use the --symmetric switch as follows:
gpg --symmetric plaintextfile.txt
#you will be prompted twice for the passphrase that will be used for the symmetric cipher
#person who wishes to decrypt will be challenged for the passphrase

#method to encrypt pipeline input to a file
#you will be prompted for the symmetric passphrase
echo "heron"|gpg2 --symmetric -o /home/fubar/e.enc
#doesn't work on RHEL7. I have to encrypt from a file or i don't get the passphrase prompt

Excellent reference on gpg keys:#

https://davesteele.github.io/gpg/2014/09/20/anatomy-of-a-gpg-key/
see also https://tools.ietf.org/html/rfc4880

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