cd ffacalc
gprbuild

.......
 
# Whether we are working on a 'clearsigned text'
CLEARSIGN_MODE=false
 
# Set up in the selected mode:
case $ARGCOUNT in
    2) # If given two arguments, verify a 'clearsigned' text file:
        CLEARSIGN_MODE=true
        # The processed payload will end up in a temporary file:
        DATAFILE=$(mktemp) || { echo "Failed to create temp file!" >&2; \
            exit $RET_EGGOG; }
        # On exit, if in 'clearsign' mode, remove temporary file with payload:
        trap remove_temp_file EXIT
        # Expect 'Canonical Text Signature' in GPG sig packet turd
        expect_sig_class=1
        ;;
    3) # Verify Detached Signature on given Data File (third argument is path):
        # The given Data file to be verified against the Signature
        DATAFILE=$3 # i.e. path given on command line
        # Expect 'Detached Binary Signature' in GPG sig packet turd
        expect_sig_class=0
        ;;
    *) # If invalid arg count -- print usage and abort:
        echo "Usage: $0 publickey.peh signature.sig datafile"
        echo "   or: $0 publickey.peh clearsigned.txt"
        exit $RET_EGGOG
        ;;
esac
.......

.......
 
# If we are operating on a 'clearsigned' text file, $DATAFILE will be
# an empty temporary file, and the payload is to be extracted to it,
 
.......
 
if [ $CLEARSIGN_MODE == true ]
then
    # Find position of 'clearsign' payload start marker:
    CLEAR_MARKER="\-\-\-\-\-BEGIN PGP SIGNED MESSAGE\-\-\-\-\-"
    start_clr=$(grep -m 1 -n "$CLEAR_MARKER" $SIGFILE | cut -d ':' -f1)
 
    # If payload start marker was not found:
    if [ "$start_clr" == "" ]
    then
        eggog_broken_clearsigned
    fi
 
    # Discard the start marker:
    start_clr=$(($start_clr + 1))
 
    # The payload ends with the line preceding the sig start:
    end_clr=$((start_ln - 2))
 
    # Find any 'Hash:' headers:
    start_body=$(tail -n "+$start_clr" $SIGFILE | \
        grep -v -n -m 1 "^Hash:" | cut -d ':' -f1)
 
    # Skip the above headers and mandatory empty line:
    start_clr=$(($start_clr + $start_body))
 
    # If there is no payload, or the markers are misplaced, abort:
    if [ $start_clr -ge $end_clr ]
    then
        eggog_broken_clearsigned
    fi
 
    # Extract the 'clearsign' payload to the temporary file:
    cat $SIGFILE | sed -n "$start_clr,$end_clr p" | \
        sed 's/[ \t]*$//; s/^- //' | \
        awk '{printf("%s\r\n",$0)}' \
            > $DATAFILE
 
    # Remove the trailing CR,LF ending:
    truncate -s -2 $DATAFILE
 
    # After this, proceed exactly like with 'detached' sigs, but
    # with the expected 'class' being 1 rather than 0.
fi
 
.......

./litmus.sh asciilifeform.peh asciilifeform-clearsigned.txt

VALID GPG RSA signature from asciilifeform <stas@loper-os.org>