How to edit PDF?

[Tristan Wibberley]

David Teague(T-bird acct) wrote:

> 
> That is one use for MD5 check sums. It doesn't make the
> file inviolable, but it gives the recipient an almost unbreakable
> check against tampering.

MD5 based signatures probably don't do that anymore. md5 is now pretty
easy to break (a researcher recently released a tool to find md5
collisions) and any file format that enables you to make changes that
are not apparent when rendered is extremely susceptible to such attacks.
That includes pdf and postscript. You should certainly be using at least
SHA-1 for this now.

-- 
Tristan Wibberley