verify_digest(){	# $0 method file string
  case "$1" in
  *)
    DIGEST=`echo "$1" | tr a-z A-Z`
    [ "$DIGEST($2)= $3" = "`openssl $1 $2`" ]
    ;;
  esac
}
verify_signature(){	# $0 url|id ... sig
  while [ "$1" != "" ]; do
    case "$1" in
    0x*)
      gpg --recv-keys "$1" || return $?
      ;;
    http:*|ftp:*)
      curl "$1" | gpg --import || return $?
      ;;
    *)
      gpg --verify "$1"
      return $?
    esac
    shift
  done
}
error_out(){	# $0 message ...
  echo "$@" 1>&2
  exit 1
}

curl -RO -C - http://ftp.gnu.org/gnu/wget/wget-1.11.4.tar.gz
curl -RO -C - http://ftp.gnu.org/gnu/wget/wget-1.11.4.tar.gz.sig

verify_signature 0x4A1B4EB1 wget-1.11.4.tar.gz.sig || error_out "$0: stopped at line $LINENO"

tar xvzf wget-1.11.4.tar.gz