E. Archive extra data record: (EFS)
archive extra data signature 4 bytes (0x08064b50)
extra field length 4 bytes
extra field data (variable size)
The Archive Extra Data Record is introduced in version 6.2
of the ZIP format specification. This record exists in support
of the Central Directory Encryption Feature implemented as part of
the Strong Encryption Specification as described in this document.
When present, this record immediately precedes the central
directory data structure. The size of this data record will be
included in the Size of the Central Directory field in the
End of Central Directory record. If the central directory structure
is compressed, but not encrypted, the location of the start of
this data record is determined using the Start of Central Directory
field in the Zip64 End of Central Directory record.
F. Central directory structure:
[file header 1]
.
.
.
[file header n]
[digital signature]
File header:
central file header signature 4 bytes (0x02014b50)
version made by 2 bytes
version needed to extract 2 bytes
general purpose bit flag 2 bytes
compression method 2 bytes
last mod file time 2 bytes
last mod file date 2 bytes
crc-32 4 bytes
compressed size 4 bytes
uncompressed size 4 bytes
file name length 2 bytes
extra field length 2 bytes
file comment length 2 bytes
disk number start 2 bytes
internal file attributes 2 bytes
external file attributes 4 bytes
relative offset of local header 4 bytes
file name (variable size)
extra field (variable size)
file comment (variable size)
Digital signature:
header signature 4 bytes (0x05054b50)
size of data 2 bytes
signature data (variable size)
With the introduction of the Central Directory Encryption
feature in version 6.2 of this specification, the Central
Directory Structure may be stored both compressed and encrypted.
Although not required, it is assumed when encrypting the
Central Directory Structure, that it will be compressed
for greater storage efficiency. Information on the
Central Directory Encryption feature can be found in the section
describing the Strong Encryption Specification. The Digital
Signature record will be neither compressed nor encrypted.
