self encrypted bash script

selfcrypted.sh

# gets the line number in this script of the "PAYLOAD:" line
echoPayloadLinenum() {
  echo $(grep --text --line-number '^PAYLOAD:$' $0 | cut -d ':' -f 1)
}

# prints only the payload
echoPayload() {
  local payload_linenum=$(echoPayloadLinenum)
  local crypted_linenum=$((payload_linenum + 1))
  
  tail -n +$crypted_linenum $0
}

# prints this script without the payload
echoSelf() {
  payload_linenum=$(echoPayloadLinenum)

  head -n $payload_linenum $0
}

# echoes the decrypted payload after user types in password
echoDecryptedPayload() {
  PAYLOAD=$(echoPayload)
  echo "$PAYLOAD" | gpg -d
}

# executes the decrypted payload after user types in password
runDecryptedPayload() {
  SCRIPT=$(echoDecryptedPayload)
  echo "$SCRIPT" | sh -
}

if [[ $* == *--encrypt* ]]; then
  echo "encrypting new payload"
  # clear payload
  echo "$(echoSelf)" > $0
  gpg -c -a >> $0
  exit 0
else
  runDecryptedPayload
  exit 0
fi

PAYLOAD: