Does DESCHALL use floating point arithmetic?
No. • What flags were used for compilation? Most have been compiled with -O3. • What is “bitslicing,” and why are the bitslice clients so fast? This is a technique introduced by Eli Biham. Biham implements DES by representing S boxes by their logical gate circuits. This view is taken of the entire cipher. The circuit is then computed 64 times in parallel. The entire “circuit” has around 16,000 gates. So in 16,000 instructions, DES can be computed 64 times on 64-bit processors. Using this method, the number of instructions needed to perform DES encryption is about 300, versus 600+ in other fast DES implementations. Processors of other sizes: 32, 16, 8 bits, etc. can use the same approach. However, in 16,000 instructions, they’ll perform only as many encryptions as the host architecture’s word size. So, although 64-bit processors will be able to perform 64 encryptions in 16,000 instructions, 32-bit processors will perform 32 encryptions, 16-bit will do 16, 8-bit will do 8, etc. • Can I s
