here is Mikkelson's macro, with a few cycles shaved. on my machine there is a small but measurable improvement. DesRound macro RoundNo,reg1,reg2 mov eax, DWORD PTR (RoundNo*8) [ebp] xor ebx, ebx mov edx, DWORD PTR (RoundNo*8+4) [ebp] xor eax, reg1 xor edx, reg1 and eax, 0fcfcfcfch mov bl, al and edx, 0cfcfcfcfh mov cl, ah ror edx, 4 xor reg2, DWORD PTR _des_SPtrans[ebx] mov bl, dl xor reg2, DWORD PTR _des_SPtrans[0200h+ecx] mov cl, dh shr eax, 16 xor reg2, DWORD PTR _des_SPtrans[0100h+ebx] mov bl, ah shr edx, 16 xor reg2, DWORD PTR _des_SPtrans[0300h+ecx] mov cl, dh and eax, 0FFh and edx, 0FFh xor reg2, DWORD PTR _des_SPtrans[0600h+ebx];ebx mov ebx,DWORD PTR _des_SPtrans[0700h+ecx] xor reg2, ebx mov ebx,DWORD PTR _des_SPtrans[0400h+eax] xor reg2, ebx mov ebx,DWORD PTR _des_SPtrans[0500h+edx] xor reg2, ebx endm At 10:19 AM 1/14/97 -6, Peter Trei wrote:

I hope you'll look at Svend Olaf Mikkleson's latest DES round replacement for libdes. He seems to have gotten the round down to 18 clock cycles. I have not yet had a chance to try it myself.

see: http://inet.uni-c.dk/~svolaf/des.htm

Peter Trei trei@process.com

Peter Trei Senior Software Engineer Purveyor Development Team Process Software Corporation http://www.process.com trei@process.com