[mdb-dev] [PATCH] implement handling of encrypted databases

[<da...@co...>]

Hi Brian,

This patch (on top of all of my other patches, 00 thru 18, which I can
resend to you if you want) implements handling of encrypted databases.

The technique for encrypting databases by access appears to be as follows:

- each data page except for page 0 (2k pages for jet3, 4k for jet4) is
encrypted separately using the RC4 algorithm and with a different key

- the key can be obtained by XORing together the following:

  - the database key, found at offset 0x3e from the start of the file
  - the 'unencrypted' key, found at offset 0x3e of any unencrypted 
    database (this appears to be 0x4ebc8afb when taking endianness 
    into account)
  - the page number

The existing code already extracted the database key, and XORed it with 
the number 0xe15e01b9.  I don't know where this number came from, but I 
can imagine there may be more than one 'unencrypted' key.  I added the rc4 
routines to src/libmdb/file.c.  They could be replaced easily with calls 
to openssl (the interface I used is almost identical to the openssl 
routines).

This works for the one encrypted database I needed to access. YMMV.

David

P.S. to enable other people to find this post with a search engine I 
include the following keywords.  I had a really hard time finding out 
information about this topic.

msaccess microsoft ac97 access97 mdb dbEncrypt CompactDatabase


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| David Mansfield              | 
| mdb...@db...       | 
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