When encrypting a .ZIP file, from the documentation it looks like either /E3 or /YC will both cause AES-256 encryption to be used. So is there any difference between using one or the other (or using both)?
It doesn't look like you actually used the /s option, which I think is prerequisite for using any of the other encryption options. Sorry, I forgot to mention that in my first post, but thought that it'd be presumed.
Actually it should /e3, but nevertheless, the ZIP files had different hashes when I used /e3 vs /yc. In fact, I tried using both options on the same command line, and that produced yet another different hash. Used names test1.zip, test2.zip, and test3.zip. Zipped the same exact file each time and used /s"password" on all of them. All 3 ZIP files were the same size.
/e3 (AES256) and /yc (AES256) has the same filesize but ARE different.
I used those commands ...
zip /e0 /s"test" test_0.zip test_to_enc.txt
zip /e1 /s"test" test_1.zip test_to_enc.txt
zip /e2 /s"test" test_2.zip test_to_enc.txt
zip /e3 /s"test" test_3.zip test_to_enc.txt
zip /yc /s"test" test_yc.zip test_to_enc.txt
Even "/e3 /yc" and "/yc /e3" are different ... see above ...
Also interesting maybe: for example with WinRar (current release v6.11) I could only unpack the "/e0 (Zip 2.0)", same with integrated solution of Total Commander (current release v10.50). With 7-Zip (current release v22.01) it was no problem (could unpack all files)!
PS: I assume you have the same file sizes because you used a larger test file for compressing/encrypting. However: I have principally the same behaviour as you - different AES256 files ... the question is just WHY ...