> My draft patch series uses Skein/Threefish. The authors conveniently > specified a way to use it as a PRNG, and it's very fast without > special hardware support (consequently, for all kinds of hardware.) > On my laptop, reading from /dev/urandom becomes about 25 times faster > for large reads, and about 40% faster for small reads where the > syscall overhead is more important.
Well, /dev/urandom is documented as being *deliberately* slow. It's meant only to produce 128 to 256 bits of seed material for CPRNG. I don't know if Ted considers speeding it up to be goal or an antigoal. :-) One thing i've thought about is adding a /dev/frandom, which is seeded once at open time and then produces a "reasonably strong" large block of cryptographic output, very quickly. (Key size between 128 and 192 bits.) I understand why Ted didn't do this in the first place, but the number of people I see doing something like "cat /dev/urandom > /dev/sdx" to test incompressible data is remarkable. If the additional code is small, perhaps it's worth doing. BTW, if it helps on 32-bit platforms I can get you rotate constats for a 32-bit version of threefish. I haven't generated a key scheduling constant, though. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
