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Re: Bignums

I believe the real issue is which format is used by various crypto 
libraries, where bignums will be used.  I can think of RSAREF, BSAFE and 
crypto++.  When I fill in a public key for one of these libraries to use, I 
would like to use memcpy rather than a byte-reversing for() loop.

BSAFE, at least, takes most significant byte first (in lowest address).
I assume RSAREF does as well.
I haven't looked inside crypto++ for this.

I grant that it is more efficient to have the least significant byte in the 
least address.  I suspect that these libraries actually swap bytes 
internally.  However, we are presented with a programmer's interface, at 
least for BSAFE, in which the most significant byte is first.  If we encode 
bignums as least significant byte first, then we are forced to byte-swap
whenever we use them.

 - Carl

|Carl M. Ellison  cme@cybercash.com   http://www.clark.net/pub/cme |
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