![]() ![]() You may need to implement CTR-LE yourself on top of the AES cipher (or AES-ECB, which is kind of the same).Īlso note that the ZIP - uh - standard defines an encrypted header, so the start of the decrypted plaintext won't be the file contents. Nothing prohibits the use of a little endian counter for CTR mode, but in 99% of the cases it'll be big endian. This is all C-code, so endianness is defined by the platform, and mostly that means little endian. The only thing that is a bit weird is that the counter is in little endian. I'll assume that you have already performed PBKDF2 with the static 1000 iterations defined (which is, uh, on the low end of security), and that the two key check bytes have been validated.ĪES itself is no different, and it seems that Winzip doesn't use anything special. The only other lead I could find was the implementation from the Brian Gladmann him self: but it lacks documentation and goes a little above my knowledge. ![]() ![]() Unfortunately documentation on the internet regarding the WinZip AES sepcification are scarce. Would it be possible to leverage an existing library and make a small change to make it work? If so what would that change be? I could try to mimic the same logic in dart which is duable but challenging. I've downloaded this nodejs package and was able to confirm that my input data was valid so my question is why are there multiple implementations of AES? And what would be the best approach to implement this in dart? It is called a Gladmann specific implementation. So I looked at a nodejs library that used a special implementation for decrypting that does not seem to be exactly equal to standard AES. I'm able to extract the encryption key and the cipher text according to the spec: encryptionKey: 9f2df21ad65ff7f33b817c5686042f1dc038f0290cbe0189f2ee2bb610bf033dĮxpected: 68656c6c6f20776f726c64 (hello world)Īny tool or package that I use is not able to decrypt it in to the right message. Using 7-Zip I was able to create an example file according to the standard. I'm trying to write a function in dart that can can decrypt a file inside a zip that is encrypted using the WinZip AES-256 standard. ![]()
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