Re: Dictionary searching code

[Simon Spero <ses@tipper.oit.unc.edu>]

On Fri, 19 Apr 1996, Adam Shostack wrote:

> 
> 	Does anyone have some code that will search a dictionary, and
> tell me *quickly* if an arbitrary chunk of text is in the dictionary?
> Pre-indexing steps are fine, as is using big chunks of disk for hash
> tables.  The point of course, is to check arbitrary possible plaintext
> that a test decryption produces.

You could try using isite (see http://www.cnidr.org/), which is a pretty 
cool search engine, and should work well enough, and the patrie structure 
could make restarts really fast . 

The real answer to your question depends almost entirely on the machine
you wish to run it on- is memory not a problem? If so, tries may be your
best bet, though you may have bad cache interactions. Otherwise, you might
be best going for a probabalistic approach and using hash table to elimate
definite non-matches, then an AVL-Tree or similar for confirmation. If you
just use a single bit for each hash-table datum, you can afford to make
the table pretty sparse

Simon
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