well, when talking about 64 bit encryption, imagine the following:
there are sixty four bits all standing in a row, and each one can be either a one or a zero. the number of combinations this can create is 9223372036854775808 so basically anybody trying to crack this will need to try that many combinations (and it's a lot, is it over a few googolplex? i lose count after the trillions).
64 bit encryption sounds like it might be twice as good as 32 bit encryption but actually if you got 32 bits and made them all stand in a row, bearing in mind that each one could be a one or a zero, the total number of combinations they could express would be 2147483648 which is actually 4294967296 times less possible variety (than a 64 bit number) if this calculator is to be believed.
Now the next thing to do is determine the difference between 32 bit processing and 32 bit expressions. if i had a continuous stream of data and it was being expressed as 32 bit data, then a 32 bit processor would be fine to have that data run in and out all along the 32 lane highway (metaphorically) leading to and from the CPU, but if i wanted to process a 64 bit stream i would need to send the first 32 bits and then the next 32 bits, and get the processor to try and add them together internally to recreate the 64 bit original thing. Then whatever calculations need to be performed need to be done via some software that knows how not to get a 64 bit thing messed up while it's inside a 32 bit processor (i think, my knowledge of processors is limited*). this is going to be slow and buggy compared with using a 32 bit stream of data on a 32 bit processor or a 64 bit stream of data on a 64 bit processor.
one 64 bit exprsssion however can be dealt with a lot easier (by a mere 32 bit processor) than a constant barrage of data though. after all, we are only talking about one actual number here (as opposed to the stream of data we had in the last paragraph), and depending on the encryption algorithms, there's probably not a huge deal of calculation got to be done with it. you can just split it up into two halves and send the halves in one after the other, it reaches the processor as two seperate 32 bit 'words'** and can be processed by software that is sympathetic to the fact that it is dealing with one 64 bit number inside a 32 bit processor. again, it'll be slower because of all the adding and so on that needs to be done to make sure it works out right, but with today's multibillionjigawattamphertz computers, it's hardly a noticable difference, unless you have a continuous stream of such 64 bit numbers, see above (example, ever tried to play an N64 ROM on an emulator on a 32 bit computer? well now you know why).
*nonexistent
** since 16 bit processors came along, people have been saying "words" where they used to say "bytes" - this is because everybody knows a byte is one chunk of 8 bits, so they needed to come up with a term that means a 'bite' of data, but can be more than 8 bits. 'word' works fine. except you need to specify '16 bit word' or '64 bit word' or people won't know what you are on about.
[ April 09, 2003: Message edited by: Calum: crusader for peace & freedom ]
