error "cannot sign with OpenPGP: passphrase file does not exist"
      }
    } else {
      error "cannot sign with OpenPGP: passphrase file is not configured"
    }
  }

  #
  # NOTE: This procedure returns a list of the same size as the list argument
  #       value.  Each element will have one pair of surrounding double quote
  #       characters removed -IF- they are the first and last non-whitespace
  #       character of that element.  A script error should not be raised by
  #       this procedure.
  #
  proc dequoteList { list } {
    set result [list]

    foreach element $list {
      set trimElement [string trim $element]
      set trimLength [string length $trimElement]

      if {$trimLength >= 2 && \
          [string index $trimElement 0] eq "\"" && \
          [string index $trimElement end] eq "\""} then {
        lappend result [string range $trimElement 1 end-1]
      } else {
        lappend result $element; # verbatim
      }
    }

    return $result
  }

  #
  # NOTE: This procedure attempts to create a Harpy (script) certificate for
  #       the specified (named) file.  Non-zero is only returned if the Harpy
  #       (script) certificate is created successfully.  A script error should
  #       not be raised by this procedure.  The fileName argument must be the
  #       fully qualified path and file name of the file to be signed.  This
  #       procedure assumes that the Harpy package for Eagle is installed and
  #       ready for use (i.e. it can find a valid license certificate).
  #
  # <internal>
  proc createHarpyCertificate { fileName } {
    global env
    variable harpySignCommand
    variable pkgr_harpy_path

    set toolFileName \
        [file nativename [file join $pkgr_harpy_path sign.eagle]]

    set scriptFileName [file nativename $fileName]

    if {[info exists env(PKGR_VENDOR)]} then {
      set vendor $env(PKGR_VENDOR); # NOTE: Configured default.
    } else {
    set vendor "Mistachkin Systems"; # NOTE: System default.

      set vendor "Mistachkin Systems"; # NOTE: System default.
    }

    if {[isEagle]} then {
      set shellFileName [formatExecArgument [info nameofexecutable]]
      set runtimeCommandLine [getRuntimeCommandLine [getShellExecutableName]]
      set toolFileName [formatExecArgument $toolFileName]
      set scriptFileName [formatExecArgument $scriptFileName]
      set vendor [formatExecArgument $vendor]

      if {[catch {
      if {[set code [catch {
        eval exec -success Success [subst $harpySignCommand]
      }] == 0} then {
      } error]] == 0} then {
        return true
      } else {
        pkgLog [appendArgs \
            "Harpy certificate was not created (from Eagle): " \
            [formatResult $code $error]]
      }
    } else {
      #
      # HACK: Make sure that Eagle is loaded into this process so that we
      #       can figure out the shell for it and then [exec] out to that
      #       shell.
      #
      makeEagleReady

      set shellFileName [eagle {
        file join [file dirname [lindex [info assembly] end]] EagleShell.exe
      }]
      set runtimeCommandLine [dequoteList [eagle {
        apply [list [list] {
          set directory [file dirname [lindex [info assembly] end]]

          foreach fileNameOnly [list EagleShell.dll EagleShell.exe] {
            set fileName [file join $directory $fileNameOnly]

            if {[file exists $fileName]} then {
              return [getRuntimeCommandLine $fileName]
            }
          }
        }]
      }]]

      if {[catch {
      if {[set code [catch {
        eval exec [subst $harpySignCommand] 2>@1
      } result] == 0} then {
      } error]] == 0} then {
        return true
      } else {
        pkgLog [appendArgs \
            "Harpy certificate was not created (from Tcl): " \
            [formatResult $code $error]]
      }
    }

    return false
  }

  #

    #       package scripts.
    #
    variable harpySignCommand; # DEFAULT: {${shellFileName}} -file ...

    if {$force || ![info exists harpySignCommand]} then {
      set harpySignCommand ""

      append harpySignCommand {{${shellFileName}}}
      append harpySignCommand {${runtimeCommandLine}}
      append harpySignCommand { -noArgumentsFileName -file {${toolFileName}}}
      append harpySignCommand { {${scriptFileName}} {${vendor}}}
    }

    #
    # NOTE: Verify that the package script matches the current language
    #       when called from the [package unknown] handler?