What's the easiest way to compute the MD5 hash value of a file? [more inside]
posted by chitlin on Jul 23, 2009 - 18 answers

How do I share images securely through an RSS feed? [more inside]
posted by gensubuser on May 6, 2009 - 8 answers

How weak is it smart to allow my GPG key passphrase to get? [more inside]
posted by ChasFile on Aug 8, 2008 - 8 answers

Help a PGP/GPG noob hold a key signing party. [more inside]
posted by zenja72 on May 26, 2008 - 12 answers

Help me find this cryptography book... [more inside]
posted by Marky on Mar 16, 2008 - 8 answers

What are some fun and simple puzzles or cryptography I can solve with Python to help me learn the basics? [more inside]
posted by cowbellemoo on Feb 28, 2008 - 12 answers

Where can I find some good resources that contrast public key cryptography algorithms (like RSA) with Elliptic Curve? [more inside]
posted by pallak7 on Dec 5, 2007 - 5 answers

AskMefi, put on your cryptography hats and help me crack a code... [more inside]
posted by UKnowForKids on Jul 11, 2007 - 23 answers

Where can I purchase a color-nicely bound reproduction of the Voynich Manuscript? [more inside]
posted by dmd on Apr 17, 2007 - 7 answers

Can someone direct me on the right path to break this code? [more inside]
posted by neurodoc on Sep 16, 2006 - 12 answers

What is the point of using a salt when encrypting passwords in a web application? [more inside]
posted by chrismear on Aug 26, 2006 - 15 answers

Cryptofilter: My daughter is at summer camp and I can snail mail her or I can send email that will be printed out and delivered. The email is fast but readable by whoever prints/delivers the paper etc. Looking for a cipher that would be easy to learn and use... [more inside]
posted by kaytrem on Aug 8, 2006 - 21 answers

Is Scientific American's spell-checker broken? (via justkevin) [more inside]
posted by Blazecock Pileon on Aug 4, 2006 - 9 answers

What's the best way to encrypt an external hard disk? (Mac OS X) [more inside]
posted by dance on Apr 22, 2006 - 4 answers

So last night on the train I saw a passenger with a small blue paper book titled "OFFICIAL CYPHER" [more inside]
posted by sol on Mar 21, 2006 - 10 answers

CryptographyFilter: I'm an obsessive journaler, partly because I enjoy writing ideas etc down in my journals, partly because I have a terrible memory. Every now and then I would like to be able to record something in my journal that I wouldn't want to be read by someone who was less respectful of my privacy than I would hope them to be, or by someone who picked up one of my journals (which always have my contact details in the front) should I misplace one. [more inside]
posted by anonymous on Jan 2, 2006 - 56 answers

Could the US government's efforts to scan the contents of everyone's email be overloaded by everyone routinely using encryption for every message? [more inside]
posted by pracowity on Dec 21, 2005 - 33 answers

A friend of mine and I were wondering today how encryption was done in character-based languages like Chinese and Japanese before the advent of computerization. Whereas all kind of substitution and transposition ciphers come to mind immediately for letter based languages like Latin, it isn't obvious how you could use them for a language with many thousands of distinct characters.
posted by sindark on Dec 5, 2005 - 9 answers

How do we know the mathematical models of physics — equations modeling the universe — apply across the universe, to data we collect about the universe that may be billions of years old? (What would be the process for verifying this?) [more inside]
posted by Rothko on Dec 2, 2005 - 22 answers

Needed: a photo or at least more information about a particular system of coded communication supposedly used in ancient china along the Great Wall. Either my google-fu is failing me or I dreamed this whole thing up. [more inside]
posted by fatllama on Mar 9, 2005 - 2 answers

Given a couple of encrypted hash strings, I need to identify the algorithm used to generate the hashes so that I can brute-force decrypt them. More inside.. [more inside]
posted by mrbill on Jun 16, 2004 - 16 answers

Prompted by the unsolved codes thread in the blue, I'm trying to remember the name of one that I didn't see there. I think I read about it on MeFi at some point. ISTR that it took (takes?) the form of annual ads in a college newspaper (out west somewhere?) on a given day. For some reason May Day is stuck in my head, but googling for it doesn't reveal anything. This went on for several years, and may still be occuring, but no one has ever figured out what it's all about. Does this ring any bells for anyone? My google fu is failing, and I'm going bonkers!
posted by jammer on May 18, 2004 - 4 answers

Does anyone know of any famous codes or ciphers that have gone unsolved for lengthy periods of time or remain unsolved? I am thinking specifically of things like The May Day Mystery and the Voynich Manuscript (also here). So things more like those and generally less like the Beale Cipher. Maybe something to do with Art Brut or Outsider art or perhaps Kabbalic systems like Gematria. Or, if all else fails maybe something by the Rosicrucians or Freemasons?

Put another way, I am looking for cryptic and complex visual systems that maintain an internal logic (however faulty or suspect) and ESPECIALLY anything having to do with the interpretation and/or decipherment of such systems.
posted by mokujin on May 7, 2004 - 2 answers