From: Ray Arachelian <sunder@escape.com>
Date: Thu, 3 Aug 95 08:48:35 PDT
To: Bill Stewart <stewarts@ix.netcom.com>
Subject: Re: building libraries
In-Reply-To: <199507310521.WAA08413@ix4.ix.netcom.com>
Message-ID: <Pine.BSD/.3.91.950803113122.12078M-100000@escape.com>
MIME-Version: 1.0
Content-Type: text/plain


On Sun, 30 Jul 1995, Bill Stewart wrote:

> If you did everything in an RSAREF-compatible manner, that would help;
> I think somebody outside the US has written an RSAREF-clone.
> Some problems include building programs that have generic-callout hooks
> instead of crypto-specific hooks (so that they don't get bitten by ITAR),
> while still maintaining reasonable efficiency and convenience.

One way to achieve this is to provide multi-layered generic "compression" 
hooks which get called in this manner:

 Compress[x](char *bufferin, size_t insize, char *bufferout, size_t *osize);

Then you chain several of these by alternating the in/out buffers, say 
something like this:

 for (i=0; i<MAXCOMPRESSORS; i+=2)
 {
  Compress[i](buffer1,size1,buffer2,&size2);
  Compress[i+1](buffer2,size2,buffer1,&size1);
 }

To decompress, you'd do something like this:

 for (i=MAXCOMPRESSORS-1; i; i-=2)
 {
  Decompress[i+1](buffer2,size2,buffer1,&size1);
  Decompress[i](buffer1,size1,buffer2,&size2);
 }

This lets you set up a chain of compressors, each compressing the output 
of the previous levels.  And what you do is allow these compressors to be 
external to the program!  (If one or more of those should be hooks to 
encrypt, well, hey, that's just a 'bug' ;-)

Basically this does C1(C2(C3(C4...CN(text)))))...) to compress the output of 
the previous compressors.  I would reccomend that the last in the set be 
the encryptors or else all the other compressors would fail. :-)

Now, would >THAT< be exportable?

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