Re: Initial Permutation

"Mok-Kong Shen" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
>
>
> Shiftytitan702 wrote:
> >
> > how does one go about doing the initial permutation of DES in C++,
> > without using "des.h", or some other specific encryption include
> > files.
> >
> > how do i transpose for example, i need to move bit 58, of the
input to
> > the first bit of the output, bit 50 to the second position, etc
>
> There is evidently the simple/straightforward, though
> possibly quite poor, method: Have the bits in an array
> and permute it acoording to the specification. Maybe
> you are looking for programming tricks to do it much
> better. In that case you would need to study some
> concrete implementations. (I guess the code in AC
> could be helpful.)
>
> M. K. Shen

If I remember correctly, Dan Hoey's algorithm is particularly
effective.

--
Hap