How to determine the existence of encryption headers?

Question

According to the .ZIP File Format Specification (dated September 1, 2012), the overall .ZIP file format is as follows:

[local file header 1]
[encryption header 1]
[file data 1]
[data descriptor 1]
.
.
.
[local file header n]
[encryption header n]
[file data n]
[data descriptor n]
[archive decryption header]
[archive extra data record]
[central directory header 1]
.
.
.
[central directory header n]
[zip64 end of central directory record]
[zip64 end of central directory locator]
[end of central directory record]

I'm able to determine the presence/position of local file headers, central directory headers and the end of central directory record by means of the respective signatures.

How can I determine the existence or not of the encryption headers? Specifically, I want to know, for any given file with my zip, whether the file data immediately follows the local file header or not...

Answer 1

Section 4.4.4 of the specification explains it:

4.4.4 general purpose bit flag: (2 bytes)

   Bit 0: If set, indicates that the file is encrypted.

Therefore, and given that the encryption header has a fixed size, you know what to do ;)