From: Martin Langhoff Date: Wed, 30 Apr 2008 02:58:53 GMT Subject: Re: About git and the use of SHA-1 Message-ID: <46a038f90804291958u14eddc49sb54c7fd4a3a10381@mail.gmail.com> In-Reply-To: <7f9d599f0804291331v2f44bee1y29c1580d68a3107a@mail.gmail.com> On Wed, Apr 30, 2008 at 8:31 AM, Geoffrey Irving wrote: > I sincerely hope that pdf/postscript don't allow the internal > rendering code to branch based on the current date. That would be an > absurd security hole, and would indeed make you entirely correct. If PS is Turing complete, and does know about dates. So yes, you can make such conditionals. That original md5 paper with the 2 PDF files is mainly a good example that you should trust binary blobs, that's all. The md5 trick is a nice demo, but misses the point entirely. I can't find it now, but someone had written a PDF file that printed Pi computing in inside the PS VM. The tiny file would keep the printer churning out paper until it ran out of memory. :-) cheers, m -- martin.langhoff@gmail.com martin@laptop.org -- School Server Architect - ask interesting questions - don't get distracted with shiny stuff - working code first - http://wiki.laptop.org/go/User:Martinlanghoff