Protected Postscript

If a PDF is encrypted it can still be converted to postscript. However the postscript can then not be converted back to PDF by ps2pdf.

This PostScript file was created from an encrypted PDF file.
Redistilling encrypted PDF is not permitted.
Error: /undefined in --eexec--

If the postscript file is opened with an editor, the ĺines causing this can be found under "mark currentfile eexec"

%% Removing the following eleven lines is illegal, subject to the Digital Copyright Act of 1998.
mark currentfile eexec
BLA BLA BLA BLA BLA BLA
BLA BLA BLA BLA BLA BLA
BLA BLA BLA BLA BLA BLA
BLA BLA BLA BLA BLA BLA
BLA BLA BLA BLA BLA BLA
BLA BLA BLA BLA BLA BLA
BLA BLA BLA BLA BLA BLA
BLA BLA BLA BLA BLA BLA
BLA BLA BLA BLA BLA BLA
cleartomark

Removing those and saving the file would prevent the error, however according to the comment this is not allowed.