gpgsig

#!/bin/bash
#
# gpgsig, a little script to sign your gpg/pgp keys
#
# Copyright 2006,2013 Aron Griffis <agriffis@n01se net>
# Released under the GNU GPL v2
# 
# Based loosely on ideas Damien Chrisment's gpgsig, but written from scratch to
# be simpler and just do what I need.  Simply:
#
# 	gpgsig keyid
#

if [[ -z $GPGSIG_USER ]]; then
    echo "Please set GPGSIG_USER=\"Your Name <email@domain>\"" >&2
    exit 1
fi

: ${GPGSIG_SERVER:=subkeys.pgp.net}

function select-key {
    typeset keys defkey
    
    gpg --recv-key "$1" || gpg --search-keys "$1"
    keys=$(gpg --list-keys "$1" 2>/dev/null)
    [[ -n "$keys" ]] || return 1

    # first key returned is the default
    defkey=${keys#*/}; defkey=${defkey%% *}

    # if there are multiple keys, ask the user
    if [[ $(grep -c '^pub' <<<"$keys") -gt 1 ]]; then
	while true; do
	    echo
	    echo "$keys"
	    echo
	    read -p "Please select a key [$defkey] " k
	    if [[ -z $k ]]; then
		k=$defkey
	    else
		k=${k#*/}
		[[ ${#k} == 8 && $keys == */"$k "* ]] && break
		echo "That wasn't a valid key... please try again"
	    fi
	done
    else
	k=$defkey
    fi
}

function verify-fp {
    declare yn

    echo
    gpg --fingerprint "$k"
    echo
    read -p "Does the fingerprint match? " yn

    [[ "$yn" == [Yy]* ]] && return 0
    return 1
}

for k in "$@"; do
    select-key "$k" || exit 1 # changes the value of $k
    gpg --recv-key "$k" --keyserver "$GPGSIG_SERVER" || exit 1
    verify-fp "$k" || exit 1
    gpg --sign-key "$k" || exit 1
    gpg --list-sigs "$k"
    gpg --send-key "$k" --keyserver "$GPGSIG_SERVER" || exit 1

    # send the key to the owner
    email=$(gpg --list-keys "$k" | sed -n 's/^uid *//p' | head -n1)
    /usr/lib/sendmail -oi -t <<EOF
From: $GPGSIG_USER
To: $email
Bcc: $GPGSIG_USER
Subject: signed your key ($k)

I signed your GPG key
    $k
and uploaded it to the keyserver
    $GPGSIG_SERVER

You can also pipe this message to gpg import if you'd like
to import it directly.

Regards,
Aron

$(gpg --export --armor "$k")
EOF
done