GPG
GPG
Install
For basic gpg command:
apt install gpg
For gpg2 command installed: (just a symlink to gpg) - some programs seem to look for gpg2?
apt install gnupg2
If you want extra documentation and examples: (very very options)
apt install gnupg
Summary:
- gpg has the /usr/bin/gpg (and man)
- gnupg2' has the /usr/bin/gpg2 (and man)
- gnupg has the /usr/share/man and /usr/share/doc for general gnupg related (very very optional)
Summary Commands
gpg2 --keyserver https://pgp.mit.edu/ --search-keys <sender_name_or_address>
gpg --import <your-file>.gpg
gpg --receive-keys A9C5DF4D22E99998D9875A5110C01C5A2F6059E7
gpg --verify apache-tomcat-9.0.16-windows-x64.zip.asc
ref: [1]
Show Keys
List public keys:
gpg --list-public-keys gpg --list-keys gpg -k
List secret keys:
gpg --list-secret-keys gpg -K
Export Key
Exoprt public key:
gpg --armor --export [long_key_id] > public.gpg.asc gpg --armor --output public.gpg.asc --export [long_key_id] gpg -a -o public.gpg.asc --export [long_key_id]
Export private key:
gpg --armor --export-secret-key [long_key_id] > private.gpg.asc gpg --armor --output private.gpg.asc --export-secret-key [long_key_id] gpg -a -o private.gpg.asc --export-secret-key [long_key_id]
Note: not sure why but the --output paramter has to come before the --export paramter?? All paramters just need to come before the [long_key_id] at the end. Example:
gpg -a --export -o public.gpg.asc [long_key_id]
Default Key
To choose a default key without having to specify --default-key on the command-line every time...
~/.gnupg/gpg.conf
default-key <key-fpr>
replacing <key-fpr> with the id or fingerprint of the key you want to use by default. [1]
Encrypt Message
Encrypt message to send to another person:
gpg --encrypt --sign --armor -r person@email.com name_of_file gpg --encrypt -r person@email.com -r person2@email.com name_of_file
Note: You should include a second “-r” recipient with your own email address if you want to be able to read the encrypted message.
Decrypt Message
ASCII Armor decrypt:
gpg file_name.asc
Binary decrypt
gpg file.gpg gpg --decrypt file.gpg
Quiet descrypt (don't show all the keys that were attempted):
gpg --quiet --decrypt file.gpg
List Encrypted Receipients
This will list public keys ID the file was encrypted with (as well as some other garbage that can be ignored). If you also have the public key, it will also tell you friendly name for each of those packets (eg. name <email>)
gpg --list-packets file.gpg
ref: [2]
Sign Message
Sign with detached signature:
# binary signature gpg --detach-sign -o sig.gpg inputdata.txt
# binary signature (if you don't specify output will generate inputdata.txt.gpg) gpg --detach-sign inputdata.txt
# detach with ASCII armor signature gpg --detach-sign --armor -o inputdata.txt.asc inputdata.txt
# detach with ASCII armor signature (will generate inputdata.txt.asc) gpg --detach-sign --armor inputdata.txt
Clear sign ASCII (text) input data, including original message in the clear:
gpg --clearsign -o output.txt inputdata.txt
# will write it as inputdata.txt.asc gpg --clearsign inputdata.txt
Sign with other key:
echo "hi" | gpg --clearsign --default-key other@test.com
Verify Signed Message
Verify with detached signature:
gpg --verify sig.gpg inputdata.txt
Note: Please remember that the signature file (.sig or .asc) should be the first file given on the command line.
Verify clear signed message:
gpg --verify output.txt
Decrypt message: (Show contents)
gpg --decrypt output.txt
# write original to file, without signature gpg -d -o original.txt output.txt
Import SSH to Remote System
gpg --export-secret-key SOMEKEYID | ssh othermachine gpg --import
GitHub GPG
Generating a new GPG key - GitHub Docs https://docs.github.com/en/authentication/managing-commit-signature-verification/generating-a-new-gpg-key
Create Generate GpG Key
gpg --full-generate-key
List Keys
gpg --list-secret-keys --keyid-format=long
Export Key
Exoprt public key:
gpg --armor --output public.gpg.asc --export [long_key_id]
Export private key:
gpg --armor --output private.gpg.asc --export-secret-key [long_key_id]
Import Key
cat [keyfile] | gpg --import
Trust Key
gpg --edit-key [long_key_id] trust # - trust level (see below) save
1 = I don't know or won't say 2 = I do NOT trust 3 = I trust marginally 4 = I trust fully 5 = I trust ultimately
Sign Commit
Manually:
git commit -S -m "YOUR_COMMIT_MESSAGE"
Automatic for current local repository
git config commit.gpgsign true
Automatic for all repositories:
git config --global commit.gpgsign true
Which will set ~/.gitconfig:
[commit] gpgsign = true
[user] name = First Last email = first.last@email.com # can specify the signing key: signingkey = B96CBB1FCF115C2XXXXXXXXXXXXXXXXXXXXX
ref: [3]
Show Log Signatures
git log --show-signature
Example:
commit dceb035ce7a3de3dc49e62ce61061efd86XXXXXX (HEAD -> ci) gpg: Signature made Fri 09 Jun 2023 05:12:54 PM PDT gpg: using RSA key 6827A8ADAF633B8B03286E15C4D210675xxxxxxx gpg: issuer "name@example.com" gpg: Good signature from "Name <name@example.com>" [ultimate] Author: Name <name@example.com>
gpg --keyserver certserver.pgp.com --recv-key 0xBB7576AC
gpg --keyserver certserver.pgp.com --send-key blake@cyb.org
ref: [4]
Unknown Trust
ultimate vs unknown
You can edit your trust of a key:
gpg --edit-key user@useremail.com edit # (trust level 1-5) list quit
gpg --edit-key user@useremail.com
trust: unknown validity: unknown
gpg> trust
Please decide how far you trust this user to correctly verify other users' keys
(by looking at passports, checking fingerprints from different sources, etc.)
1 = I don't know or won't say
2 = I do NOT trust
3 = I trust marginally
4 = I trust fully
5 = I trust ultimately
m = back to the main menu
Your decision? 5
gpg> save
gpg> quit
ref: [5]
Delete Key
Delete secret key first:
gpg --delete-secret-key [LONGID] gpg --delete-key [LONGID]
Remove Passphrase
- gpg --list-secret-keys
- get key id
- gpg --edit-key XXX
- gpg> passed
- enter old password
- enter new password (leave blank) twice
- save
- quit
Ref: https://superuser.com/questions/1360324/gpg-remove-passphrase