From: manaster@yu1.yu.edu (Chaim Manaster)
Newsgroups: sci.crypt,comp.compression,comp.compression.research
Subject: Encryption/decryption on top of fulltext retrieval software.
Summary: Discussion of encryption in a fulltext database retrieval environment.
Keywords: encrypt decrypt text retrieval transparent
Date: 4 Jan 93 00:10:43 GMT
Followup-To: sci.crypt
Organization: Yeshiva University


I need to locate people who have or are working on encryption software that will work on top of text retrieval software of the type usually found on CDROM databases. While I am not a technical sophisticate let me attempt to elaborate to clarify my needs.

As I understand things, typically the retrieval software will first create in inverted index file of the textual database, and then when the user inputs his search terms the retrieval engine will quickly search the index, obtain the associated pointer to the original text in the database and retrieve the database.

When encryption is introduced into the picture untop of the above retrieval software (without modifying the retrieval software) It would seem that in order that the user enter his query terms in an unencoded fashion the encryption software first nust encrypt his search terms then enter the encrypted** inverted index located the correct entry, decrypt it, locate the associated encrypted text, decrypt it and present that to the end user, ALL DONE ON THE FLY.

** The inserted index must be encrypted as well since its is fairly easy to rebuild the original text solely from the unencrypted inverted index files.

Thus it seems to me that any encryption method must be able to use a decryption method that can start to decrypt at any random point in the encrypted file (or a large number of points as an approximation) to pick out some small portion of either the encrypted index or text files without the need do decrypt the entire file, which is usually huge, just to get at a search term in the index or the retrieved textual paragraph from the large database.

Would such an encryption scheme of necessity, merely be some form of substitution cypher and therefore not worth writing (too easy to break)? What kind of encryption shemes would be worth considering and is there any software out there (shareware, public domain or commercial) that will do the trick, or is anyone working on a similar project at the moment?

One of my main concerns is that the encryption be transparent to the retrieval
engine (or at the very least require minor modification if immpossible otherwise).

Please Email responses, I am not sure if I can access relevant newsgroups with my sites newsfeed. If I posted this to groups of marginal relevance forgive me but please at the very least suggest the appropriate newsgroups I should post to that don't require special access.

Thank you in advance for the help.

Henry Manaster

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	Henry Manaster          *     EMail: manaster@yu1.yu.edu
	Brooklyn, NY            *
                                *
	Disclaimer: The above is not necessarily MY opinion nor that 
				of anyone else :-)  ????!
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Newsgroups: sci.crypt,alt.security.pgp,alt.security.ripem