On 2010-09-17, Chris Bamford wrote:
> I am developing Java code to handle archives using commons compress
> and am currently focusing on ZIP files. I understand that ZIPs can be
> encrypted in two ways:
> (a) the contained entries can be plain text or encrypted
> (b) the whole ZIP itself can be encrypted
> QUESTION 1: Is this correct?
More or less, yes. (a) is even a bit more complex since there are
different ways an entry can be encrypted (there is an old-style
encryption and a more modern variant that signals the algorithm used).
In either case, Commons Compress doesn't support encryption of ZIPs in
any way.
> So far I only know how to handle (a), by using this method:
> public boolean checkZipEntryIsEncrypted(ZipArchiveEntry entry) {
> boolean encrypted = false;
> // Check if zip file is encrypted
> if (zfile != null) {
> if (! zfile.canReadEntryData(entry)) {
> encrypted = true;
> }
> }
> return encrypted;
> }
> QUESTION 2: is this the right way to detect encrypted entries?
encryption is one of the reasons canReadEntryData may return false,
another reason could be an unsupported compression algorithm.
> QUESTION 3: what is the right way to detect that the ZIP itself is
> encrypted?
There isn't any built into Commons Compress ATM.
Stefan
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