The Microsoft Excel File Format - OpenOffice.org

5 Worksheet/Workbook Records
5.43 FILEPASS
BIFF2 BIFF3 BIFF4 BIFF5 BIFF8
002F H 002F H 002F H 002F H 002F H
This record is part of the File Protection Block (➜4.19). It contains information about the read/write password of the
file. All record contents following this record will be encrypted (➜4.19.1).
5.43.1 Record Contents (BIFF2-BIFF5)
Record FILEPASS, BIFF2-BIFF5:
Offset Size Contents
0 2 Encryption key calculated from the read/write password (➜4.19.1)
2 2 Hash value calculated from the read/write password (➜4.18.4)
5.43.2 Record Contents (BIFF8)
From BIFF8 on it is possible to use different encryption algorithms.
Record FILEPASS, BIFF8, for BIFF2-BIFF5 weak XOR encryption:
Offset Size Contents
0 2 0000 H = BIFF2-BIFF5 weak XOR encryption
2 2 Encryption key calculated from the read/write password (➜4.19.1)
4 2 Hash value calculated from the read/write password (➜4.18.4)
Record FILEPASS, BIFF8, for BIFF8 standard encryption:
Offset Size Contents
0 2 0001 H = BIFF8 standard encryption or strong encryption
2 2 not used, should be equal to next field (0001 H )
4 2 0001 H = BIFF8 standard encryption
6 16 Unique document identifier used to initialise the encryption algorithm
22 16 Encrypted document identifier used to verify the entered password
38 16 Digest used to verify the entered password
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