Talk:Tiny Encryption Algorithm
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[edit] Efficiency versus simplicity
I'm pondering whether it's better to replace the current version, which is tuned for efficiency, with the simplest possible version, which is probably this:
void encrypt(unsigned long* v, unsigned long* k) {
unsigned long delta=0x9e3779b9, sum=0, i; /* a key schedule constant */
for (i=0; i < 32; i++) { /* basic cycle start */
sum += delta;
v[0] += (v[1]<<4)+k[0] ^ v[1]+sum ^ (v[1]>>5)+k[1];
v[1] += (v[0]<<4)+k[2] ^ v[0]+sum ^ (v[0]>>5)+k[3]; /* end cycle */
}
}
Since storing array entries in registers is a very difficult optimization to perform safely, I suspect compilers will tend to produce slow code for this. On the other hand, I just killed another 3 lines, and it's nicer to look at. Thoughts on this? Derrick Coetzee 01:53, 24 Sep 2004 (UTC)
- I've verified that gcc produces much worse code for this version on both RISC and CISC platforms. I think the version on the page should probably stay. Derrick Coetzee 01:58, 24 Sep 2004 (UTC)
- Do this will not change anything ..
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- I would expect part of the slow down to be from alias analysis; gcc has no way of knowing from the above code that v and k don't point to overlapping memory addresses, so it can't just store v[0] and v[1] in registers. Try using the restricted flag for the arguments. 198.205.32.93 17:11, 22 November 2006 (UTC)
- I would prefer to see this in the article. As the lead section says "[...] a block cipher notable for its simplicity of description and implementation", I think we should have the simplest possible example for illustrative purposes, to demonstrate its simplicty. We can just add a note saying "for a more efficient implementation, refer to ...". -- intgr 19:26, 22 November 2006 (UTC)
