“I’m a twat”, or “The case of the MD5 crypt”

twitter_fail_whale_01Proud member of the “fail whalefan club!

No wait, I mean I’m on Twitter! That’s right – yours truly is now posting 140 characters long snarky remarks every now and then on my very own Twitter channel. (But not exclusively, there’s some ironic/stupid ones too!) With the excellent Twitter gadget I even have access to both reading and writing posts from inside iGoogle. Eau de humanity, such brilliant technology.

In other news…
I was reading up on encryption algorithms for a project I’m currently doing and cringed when I noticed how many tutorial sites called MD5 an encryption algorithm. MD5 is used for hashing, which is mainly a way of verifying the integrity of a file or other input data. All hashes are fixed-size, meaning they don’t grow no matter how much data you give MD5, be it the text “Hello” or an entire music track.

Encryption on the other hand is used to conceal data from someone (a third party) and in its most simple form uses a key to encrypt (transform to so called ciphertext) and decrypt (return to the original form, also known as plaintext) the data. (a.k.a symmetric-key encryption). The output of an encryption algorithm grows depending on how much data you feed it, and is approximately 1:1 in size to the input. (Can be bigger due to overhead or smaller if encryption algorithm compresses the data.)

There is no simple way of turning a hash back into the original message or file for which it was calculated, but to turn encrypted data (the ciphertext) back to the original (plaintext), all you need is the password.

Some hash algorithms are MD5 and SHA-1.
Some encryption algorithms are ROT13, DES and RSA. (Although not all of these are symmetric-key.)

I sense this “In other news” is turning into the actual post, so I’m going to stop here and promise myself and any interested readers a full-sized follow-up articl, although the web sources below are pretty

Until then, read more on hashing and encryption!

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