V3 database inflation - format change proposal

"Rony Shapiro" <[email protected]>
Newsgroups gmane.comp.security.passwordsafe.devel
Message-ID <[email protected]>
Hi,

An interesting issue arose while playing with the V3 format:

A database with ~400 entries takes ~40kbytes to store in the V2 format.
The same data stored in V3 takes up ~62k - over 50% more!

The loading times is also longer by roughly the same amount - about ~40%.

A quick analysis shows that most of the difference is due to the 8
additional wasted bytes in the first block of each field (8 fields per
record).

Therefore, I'm thinking of modifying the field format as follows: Instead of
the first block of a field containing only four length bytes and a type
byte, which left 3 bytes unused in V2 (since Blowfish has a blocksize of 8),
but 11 (!) unused in V3,  the first block will also contain up to 11 bytes
of data.

Graphically: L = Length Byte, T = Type Byte, X = unused byte, D = Data

V2 field:
LLLLTXXX DDDDDDDD...DDDDDDDD...

Current V3 field:
LLLLTXXXXXXXXXXX DDDDDDDDDDDDDDDD...

Proposed V3 field:
LLLLTDDDDDDDDDD DDDDDDDDDDDDDDDD...

(Note that for up to 8 bytes of data, the size of a new V3 field is the same
as V2, and for 9, 10 or 11 bytes it's actually shorter by 8 bytes!)

Any comments on this proposed change?

	Thanks,

		Rony




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