Man Linux: Main Page and Category List

NAME

       sd-eng, sd-engf, sd-c - text watermarking and watermark recovery

SYNOPSIS

       sd-eng [-6] -i origfile newfile "Recipient" ["Comment"]

       sd-eng [-6] -e origfile newfile

       sd-eng [-6] -l

DESCRIPTION

       snowdrop  is  a  stenographic  text watermarking and watermark recovery
       system.  It is composed of three programs:

       sd-eng Watermark normal English text.

       sd-engf
              Watermark fine quality English  text,  yeilding  higher  quality
              output but encoding less information.

       sd-c   Watermark C code.

       The  three  programs  operate  similarly,  with the same parameters and
       usage.  The watermark is encoded in using a number of techniques,  such
       as  whitespace  reformatting,  typo  insertation,  word  substitutions,
       punctuation changes, and for C code, logic  reordering,  variable  name
       mangling, etc.

       The  watermark is a md5sum, which is retreivable from as little as 5 or
       10 lines of the watermarked document. Even large changes  to  a  medium
       sized  document  should  not  obscure  the  watermark,  as it is stored
       redundently in multiple independant channels.

       The three usage modes are adding a watermark, checking for the presense
       of   a  watermark,  and  listing  the  contents  of  your  database  of
       watermarks. Note that to later check a watermark,  you  must  retain  a
       copy of the original, un-watermarked file.

OPTIONS

       -i     Inject  a  watermark  into a file. You must pass it the original
              file,  the  filename  to  output  the  watwrmarked  version  to,
              information  about  who you intend the watermarked file for, and
              an optional comment.

       -e     Extract a watermark from a file. Needs the original file and the
              new file that you suspect bears the watermark.

       -l     Lists  the contents of the watermark database. Each of the three
              programs will have a different list.

       -6     Enable 64  bit  waterarking.  The  default  is  a  weak  32  bit
              watermark.

ENVIRONMENT

       SD_SYNONYMS
              This  variable  can  be  used  to point snowdrop at a customized
              synonyms file.

FILES

       ~/.snowdrop/database
              Database of watermarked files.

SEE ALSO

       /usr/share/snowdrop/README
              Explain snowdrop in more depth,  its  limitations,  and  how  to
              write  additional watermarking modules for other tpyes of files.

AUTHOR

       Michal Zalewski <lcamtuf@coredump.cx>

                                                                   SNOWDROP(1)