Browse Prior Art Database

Securing Compacted Data

IP.com Disclosure Number: IPCOM000047274D
Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Sarid, U: AUTHOR

Abstract

Data to be compacted is encrypted for securing the data during the compaction phase. Arithmetic compaction techniques are employed; the code pattern at any given point in the compaction security system is dependent upon code patterns of preceding data. Then a single password is logically combined with a leading edge portion of compacted data for providing masked data followed by clear text compacted data. Masking the leading edge portion prevents unauthorized decompaction of the arithmetically compacted data. Single level security is achieved by simply exclusive ORing a secret password with a leading portion of the compacted data for creating a segment of masked data preceding the clear text arithmetically compacted data.

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Securing Compacted Data

Data to be compacted is encrypted for securing the data during the compaction phase. Arithmetic compaction techniques are employed; the code pattern at any given point in the compaction security system is dependent upon code patterns of preceding data. Then a single password is logically combined with a leading edge portion of compacted data for providing masked data followed by clear text compacted data. Masking the leading edge portion prevents unauthorized decompaction of the arithmetically compacted data. Single level security is achieved by simply exclusive ORing a secret password with a leading portion of the compacted data for creating a segment of masked data preceding the clear text arithmetically compacted data. A second level of security is provided by using a pseudo-noise (PN) key rather than the password (PW) to initially mask the leading edge. The PN key is also directly inserted at some point into the clear text compacted data. Then a second compaction pass (or similar context- dependent encryption) is used to secure the newly masked data up to and including the embedded PN key. Finally, the secret PW is exclusive ORed with the leading edge to mask this new compaction, as before. The second compaction destroys the code-breaker's ability to compare the first few bytes after the masked portion with the original data and thus quickly determine that the code has been broken; the entire data stream until the embedded PN key is do...