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66 lines
2.5 KiB

Here are the notes I made while working through the ZIP file specification.
For each file:
local file header signature 4 bytes (0x04034b50)
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
|sig |v |g |c |t |d |crc |csz |usz |n |x |
PK.. ## 00 00 ?? ?? xxxx ???? ???? ?? 00
<file name><file data>
Central directory:
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)
|sig |vm|vx|g |c |d |t |crc |csz |usz |n |x |cm|dn|ia|xa |roff|
PK.. ## ## 00 00 ?? ?? xxxx ???? ???? ?? 00 00 00 00 xxxx ????
End of central directory:
end of central dir signature 4 bytes (0x06054b50)
number of this disk 2 bytes
number of the disk with the
start of the central directory 2 bytes
total number of entries in the
central directory on this disk 2 bytes
total number of entries in
the central directory 2 bytes
size of the central directory 4 bytes
offset of start of central
directory with respect to
the starting disk number 4 bytes
.ZIP file comment length 2 bytes
.ZIP file comment (variable size)
|sig |n1|n2|e |ne|size|off |cm|
PK.. 00 00 ?? ?? ???? ???? 00