Posts Tagged hash

Imagine you’re sitting in the pub trying to remember a film title and you just can’t, for the life of you, summon up more than the fact that it begins with an ‘N’ (or maybe a ‘D’) and it definitely has something to do with cars… and then your friend says “Casablanca” and you say “YES!  That’s it!”  Sound familiar?  Yeah, me too.  Despite being totally unsure of any details a moment before, you know beyond any doubt that you have it, the instant somebody suggests the correct answer.  It’s the difference between recall and recognition that divides frustrated vagueness from confident certainty.  But can it be useful?

The answer is yes.  There is a way to store information so that a computer can recognise the same information if it sees it again without actually knowing the information – which means that what you stored is totally secure.  It’s called one-way encryption and it’s very simple.  You put in some information (a file, a name, a password etc) and the system creates a ‘hash’.  You always get the same hash for the same input but there’s no way to input a hash and figure out the original input.  For the 32-character format we use, there are 340,000,000,000,000,000,000,000,000,000,000,000,000 different possible hashes so it’s very unlikely (1 in 3 x 10³⁸) that two different inputs will give you the same one.  So if you give me your password when you sign up, let’s say waterberry, I would generate a hash4fa29303bf3155789ae1e8969bb029ae.  Read the rest of this entry »