WINRAR no longer free

Marty_J

fwor wrote: »

Load the output from a real random (not pseudo-random) number generator into a file and give them that.

They won't be able to compress it losslessly because every bit of information in it is unique and essential to the file. They may be able to compress it slightly, but not by 98%.

Do people use files that are just random data?

Another test you might try is giving them an encrypted file and see how they get on trying to compress that by 98%...

Couldn't you just encrypt the compressed file as opposed to compressing the encrypted file?

Edit: Another one to try: take a high-resolution photo on your digital camera, rename the resulting jpeg file to something like "shoppinglist.doc" so they don't know what's in it, and give them that to compress losslessly by 98%.

Why?

fwor

Marty_J wrote: »

Couldn't you just encrypt the compressed file as opposed to compressing the encrypted file?

Would that be any use to the MOD? (Hint: the radio does the encryption, so the operator sees the content)

Marty_J wrote: »

Why?

Because their claim (as described by Cat695) is simply not achievable.

[Deleted User]

I don't understand why consumers pay for software like WinZip & WinRAR when there is plenty of freeware & open source alternatives available.

I can't get over the reason why people spend £50+ on Norton security too. Pfft!

This is MSE afterall!

timcrips

try

http://www.download.com/CoffeeCup-Free-Zip-Wizard/3000-2250_4-10057893.html?tag=mncol&cdlPid=10853623

Work for me

Marty_J

fwor wrote: »

Would that be any use to the MOD? (Hint: the radio does the encryption, so the operator sees the content)

I have no idea. The operator would only see the content if it was decompressed though surely?

Because their claim (as described by Cat695) is simply not achievable.

I believe his claim was that it "can compress any size file by 98%" (emphasis mine); not that it does compress any size file by 98%. I took this as meaning that the compression rate was variable.

I was wondering though, why you thought it would have trouble compressing a photo?

Stompa

Marty_J wrote: »

I believe his claim was that it "can compress any size file by 98%" (emphasis mine); not that it does compress any size file by 98%. I took this as meaning that the compression rate was variable.

I'd imagine that was what was meant. Clearly you cannot guarantee to losslessly compress any file by 98%. In fact some files will not be compressable at all.

Bob63

Not all files can be compressed much further as they are already compressed. JPEG, MP3, AVI files are good examples.

b.t.w. OpenOffice files (ODT/ODS/ODP) make interesting use of compression. The OpenDoc standard is pure XML, which is very wordy text, which is then stored as a zip file. It is interesting to plug an OpenOffice file into Winzip, or equivalent, and see the files that are inside.

fwor

Marty_J wrote: »

I have no idea. The operator would only see the content if it was decompressed though surely?

The encryption is designed to stop unauthorised people seeing the content. The compression stage is not.

Marty_J wrote: »

I believe his claim was that it "can compress any size file by 98%" (emphasis mine); not that it does compress any size file by 98%. I took this as meaning that the compression rate was variable.

I was wondering though, why you thought it would have trouble compressing a photo?

The claim was originally presented as An Impressive Thing. A product that "might be able to compress any size file by up to 98%" is not impressive at all.

As cheesy.mike has pointed out, a jpeg file is already compressed.

Whatever, I doubt that we'll hear back anytime soon. If the person who quoted the claim really does work for or with the MOD, he/she has probably realised by now that they are subject to a contract that doesn't allow them to discuss their work with unauthorised people. That probably includes a bunch of strangers on an Internet based forum.

TorrestheGreat

Wlater Mitty strikes again!

superscaper

fwor wrote: »

Whatever, I doubt that we'll hear back anytime soon. If the person who quoted the claim really does work for or with the MOD, he/she has probably realised by now that they are subject to a contract that doesn't allow them to discuss their work with unauthorised people. That probably includes a bunch of strangers on an Internet based forum.

I may have missed something but I didn't see any claim of working for the MOD nor that it was privilidged information. We do contract work for many military organisations but that doesn't mean every single thing is priviledged. There's plenty that's public domain knowledge and non-privilidged info. I think you're making some wildy speculative assumptions (that may or may not be right).