One way of looking at the design of a cipher is that you are taking a small fixed-block-size cipher of known good design, and finding a way to extend the security of that small block cipher to a larger block, potentially variable sized.
For example, stream ciphers (and their close cousins, 'cipher modes' like OFB, CFB, and so on) work by splitting the message into smaller blocks and applying the mini-cipher to each block in turn; but if they did that with the same key each time, the result would not be particularly secure for various reasons - weaker than the mini-cipher - so they use various means of causing interrelationships between the mini-blocks.
This brings about a property known as "avalanche"; namely, changing a single bit of the input should cause 'cascading changes' such that (on average) half of the output bits are changed, meaning that the new output is as related to the old output as two independently chosen random bit strings.
Well, the medics seem unsure as to exactly what's wrong with Sarah, so they're keeping her in the wards for observation.
They think there's some kind of infection afoot, so she's on antibiotics. Her heart rate still keeps getting high, and she seems to be having trouble regulating her temperature correctly (always either freezing or boiling), and she gets breathless if she walks ten metres to the toilet.
But the baby still seems perfectly healthy! 🙂
After not having been to a hairdresser's since somewhere in 2001, I have, in the interests of safety when working with metal, not getting it caught on things and hurting myself, not getting it blown across my face, and not getting it sticking to food between plate and mouth, I have had my hair cut.
It feels SO GOOD. Oh, and it will save in shampoo costs!
http://www.izpitera.ru/lj/tetka.swf
This thing is interesting, yet sincerely odd.
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Sarah went in for a check-up on the medical stuff, and they liked her so much they decided to keep her 🙁
She's had a chest X-ray and more samples and tests, and is staying there at least tonight, maybe more.
Bah! She hates being in hospital, especially when she's on her own. I spend lots of time there with her, but now that's take up time I'm meant to have been spending working on projects.
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Crypto / security | alaric | 
Mon 4th Jul 2005 1:07 am | 
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