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| Using Mmx Registers For Crypto | |
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| Topic Started: May 25 2006, 04:47 PM (381 Views) | |
| loki | May 25 2006, 04:47 PM Post #1 |
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Advanced Member
  ![]](http://209.85.122.85/static/1/pip_r.png)
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is this possible? Background: MMX consists of 8 registers, labled MM0 to MM7. Each register is 64 bits long. One of the concept behind MMX is called packed data types. This means that instead of using the whole register for a single 64-bit integer (quadword), two 32-bit integers (doubleword), four 16-bit integers (word) or eight 8-bit integers (byte) may be used. Now this got me thinking. If there are 8 available registers and each register can hold 8 bytes then would it be possible to use 4 registers each holding 8 8-bit integers for an input block and the remainder to hold the key. By using this method to hold and store data is it possible to use 256-bit data blocks and a 256-bit key. Is this possible at all? |
| c(x) = 3x3 + x2 + x + 2; Find the inverse | |
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| rot13 | May 25 2006, 05:08 PM Post #2 |
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Elite member
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I haven't had much need to work down at that level in a long time, but from what I have read, the MMX registers have been used quite successfully for doing crypto. I think the barrier you would hit if you tried to do a 256-bit cipher with them is that you generally need some place to put intermediate results, and if you fill up all 8 registers, you don't have any MMX registers for temporary storage. You'll probably have to copy data around a little bit more than you would like. Someone else may have a better perspective on this. |
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| loki | May 25 2006, 05:59 PM Post #3 |
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well either way, the idea sounds awsome. I really gotta stop giving myself all these projects to do. But I thinking. MMX is used for multimedia, granted the only multimedia I can someone would, want to encrypt may be satellite images or a live feed. The key could be a digital scan of someones finger. The encryption would be some sort of mixing of the two images. I think that you would use it like Public key, in that you specify who you want to send it too, the reciever needs only to scan his/her finger to confirm idenity. The idea is raw, and that is all it is an idea. I have never heard of anything like that before. If there is please post it. There are days like this I wish I had a computer science degree. |
| c(x) = 3x3 + x2 + x + 2; Find the inverse | |
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| insecure | May 26 2006, 01:08 PM Post #4 |
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Using particular registers for encryption does kind of assume that the target machine has those registers available to it, and that they are not being used for anything else. I suspect that managers of dinosaur pens would look askance at anyone who suggested they should re-engineer all their big iron to incorporate multimedia registers, for crypto or anything else! |
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| loki | May 27 2006, 04:18 AM Post #5 |
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not sure if that was an insult or not, but I do understand your point. I still think its an exciting idea. |
| c(x) = 3x3 + x2 + x + 2; Find the inverse | |
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| insecure | May 27 2006, 06:55 PM Post #6 |
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Be sure. It was not an insult. If I choose to insult you, I assure you there will be no doubt whatsoever! 
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9:16 AM Nov 8
