Why RAR compression still popular ? - Page 1
Forum section: electronics / general

author: BravoV
author_rank: Super Contributor
timestamp: May 25, 2018, 07:31:51 pm
content: I mean format like 7zip and maybe others that are freely available and open too.Are there any real advantages, I mean for today, now in 2018 ?Its not like we're still in 90's or after early doomsday of Y2K era ?

author: ChunkyPastaSauce
author_rank: Unknown
timestamp: May 25, 2018, 07:37:04 pm
content: Recovery record is a big one.

author: Red Squirrel
author_rank: Super Contributor
timestamp: May 25, 2018, 07:56:36 pm
content: Always found that odd too. Worse is when they split it up in like 200 rar files. Why do that? There's no logical reason to do that now that floppies are obsolete.

author: helius
author_rank: Super Contributor
timestamp: May 25, 2018, 08:09:56 pm
content: Quote from: Red Squirrel on May 25, 2018, 07:56:36 pmIf by "they" you mean pirates, they have certain "rules" and old habits are hard to break. Long after floppies were not used, they still split archives to go through Usenet.

author: rdl
author_rank: Super Contributor
timestamp: May 25, 2018, 08:42:41 pm
content: At least one file sharing site uses splitting to "encourage" you to pay for their service. If you are not a paying customer files are split into chunks and you can only download a part every hour or so with reduced download speed. If you subscribe, you can get the file all in one piece with no speed restriction.Anyone that uses 7-Zip and is concerned with privacy should be aware that it saves a history of all files opened in the Windows Registry.

author: Red Squirrel
author_rank: Super Contributor
timestamp: May 25, 2018, 09:37:14 pm
content: Quote from: helius on May 25, 2018, 08:09:56 pmI've seen this on torrents (Linux distros.) where they are split, but it's kinda pointless to do that since it's still just one torrent. But yeah from what I heard before it sounds like it's an old habit that just never really died.

author: Kjelt
author_rank: Super Contributor
timestamp: May 25, 2018, 10:07:45 pm
content: For newsgroups some blocks get lost, and it is much faster to repair 3 files of 100MB where a few blocks are lost than one file of 10GB with the same missing blocks in it.

author: rsjsouza
author_rank: Super Contributor
timestamp: May 25, 2018, 10:26:31 pm
content: Quote from: ChunkyPastaSauce on May 25, 2018, 07:37:04 pmI use this particular recovery feature on my sensitive backups. It somehow gives me peace of mind relying in two companies to do my backups (compression + automation).For online, certainly breaking files into smaller chunks is a great advantage. Not everyone or every corner of the world can count on high bandwidth or reliable availability.

author: TerraHertz
author_rank: Super Contributor
timestamp: May 25, 2018, 11:29:12 pm
content: RAR has a particular feature that is very useful. You can attempt to open _any_ file with the RAR utility. It does not demand that the file suffix be .RAR, nor that the rar-file header and signature number be at the start of the file. It just starts scanning the file from the beginning, looking for a rar archive.Huge benefit! It means you can take any existing file, and append a rar archive to it. For instance to a JPG image file. So you can create a file named book.jpg, which has a picture of a book cover at the start, and then an archive containing the book contents taking up most of the file size.An image viewer utility will open the file like an image, showing the 'cover pic' and ignoring the rest of the data.A RAR utility will find and open the archive of the book contents, ignoring the .jpg suffix and the cover image.Hence the term "rar-book". It's a common practice in some circles.A few examples here:http://everist.org/archives/scans/RAR-books/Why most _other_ compression utilities won't do this, I have no idea. It's a stupid design decision imo.(7-Zip does.) Edit: typo corrected. Wrote ALZip when I meant 7-Zip.This leads into the topic of "features that should be standard practice in file systems in general, but aren't." But that's for another day.

author: rdl
author_rank: Super Contributor
timestamp: May 25, 2018, 11:56:52 pm
content: Interesting.7-Zip will do it if you navigate to the file using its own file manager, then double click the file. Nothing I tried within Windows Explorer worked though. It just wanted to compress it again.

author: Halcyon
author_rank: Unknown
timestamp: May 26, 2018, 01:25:01 am
content: Quote from: Red Squirrel on May 25, 2018, 07:56:36 pmIt comes in handy, for example if you're transporting files on a medium that uses a FAT32 file system (many thumb drives) that doesn't support files over 2GB. It's good to have that option, you can turn it off.I personally use RAR for the recovery record option.

author: mariush
author_rank: Super Contributor
timestamp: May 26, 2018, 01:58:08 am
content: The splitting into lots of files was also done for easy distribution in the piracy scene ... various "groups" rush to release something and whoever publishes the "release" first wins the "race", as long as the release respects some rules. So it's often easier to upload multiple files in parallel saturating your upload bandwidth instead of uploading a single file...It's also easier to have auto upload bots pick up newly uploaded files and automatically upload them to other ftp locations and other file servers... no need to wait until the full file is uploaded.Piracy groups also use checksum files, files which contain checksum hashes (crc32 , md5 , sha etc) and generally these checksum files are uploaded first, and then the ftp server can calculate checksum of a file as it's being received and automatically reject the upload if the final checksum doesn't match the checksum in the checksum file. If you have 200 x 100 MB files, it's easier to just re-upload one 100 MB file instead of a single 20 GB file.FTP doesn't allow you to position the file pointer at 5 GB into a 20 GB file and resume writing a finite amount of bytes, overwriting a part of the previously uploaded content, so you can't overwrite a few bytes into a big file, you can only resume upload from one one, so if a byte was corrupt at 5 GB, the uploader would have to upload 15 GB again, from 5 GB to 20 GB.Way in the past, cracking groups would split big applications into 720KB / 1.44 MB floppy discs before uploading them to newsgroups and/or BBS sites , and each archive would also contain a descript.ion file or README.DIZ or FILE_ID.DIZ or some other files with special names. BBS software or FTP clients or file managers like Norton Commander or DOS Navigator would automatically detect these files and show the contents of these files, making it easier to analyze contents of archives or stuff, like bragging about how smart you are to crack that application ... think of those as twitter of NFO files , where nfo files are "release notes" from the piracy group.

author: BravoV
author_rank: Super Contributor
timestamp: May 26, 2018, 07:21:48 am
content: I understand the need for breaking up into pieces, but c'mon, people still using FTP ? I mean for the closed private group sharing ?For distribution and downloading, I thought torrent (or it's many variants) now days are far more efficient and "relatively" more secured ? Talking about congesting your bandwidth & recovery, I thought manual FTP-ing multiple files even with concurrent sessions can't beat torrent ? CMIIWFrom recovery, ok, I did it my self, all my important optical discs archives are heavily PAR-ed. But only in early 90s and also early 2000's where optical discs were preferred personal archival media as the cloud thingy was not popular back then, or even decent & reliable "personal" RAID storage solution were still infancy or at least not within personal budget.Ok, fine, for those underground or like warez scenes, that they still can't change because of habit.What I don't understand is even in formal and legit distributions still using RAR ? How come ?Tons examples out there, here a popular well known name, just see the Rigol's firmwares distribution using RAR ? WTF ?

author: Yansi
author_rank: Super Contributor
timestamp: May 26, 2018, 07:49:38 am
content: Rar popular what? No way here. All of my friends prefer 7z. And i prefer plain zip.Rarely do I see or use a rar. (Pun intended).

author: TerraHertz
author_rank: Super Contributor
timestamp: May 26, 2018, 08:32:00 am
content: Quote from: rdl on May 25, 2018, 11:56:52 pmOops. I meant to say 7-Zip does it. ALZip does not.You can just right-button drag the file to 7-Zip too.The whole MSWindows file type associations system sucks. ONE action for file type? So restrictive, and built into the Registry, so _deliberately_ not portable.Ha, using one of my RAR-book scans as an example. Those are part of an experiment.

author: Kjelt
author_rank: Super Contributor
timestamp: May 26, 2018, 10:46:09 am
content: Quote from: BravoV on May 26, 2018, 07:21:48 amYou have to realize that with torrents the stuff you downloaded is also shared back to the net and there is some bookkeeping. So in case there is a copyright or other rights involved you then act illegally.Now laws change so in many countries downloading contents with 3rd party rights are already considered illegal by it self, however the companies enforcing the laws can only detect ip addresses that are "sharing" the files themselves, not the ones downloading the files since this would mean they have to suspoena the newsserver company in a different country.Anyway if you do not have those files with rights you are right it is more effective.

author: BravoV
author_rank: Super Contributor
timestamp: May 26, 2018, 01:25:06 pm
content: Quote from: Kjelt on May 26, 2018, 10:46:09 amThis is what I mean, the excuses of correcting even just few bytes in the middle Giga bytes download is not a big deal with torrent that has quite nice recovery and error checking mechanism, the client simply just re-request the offending near by small pieces to correct that.Regarding legality, don't see if anyone is using torrent means they're bad/naughty, there are lots of legit stuffs also served in torrent style, its damn efficient and reliable compared to uploading/downloading small chunks of files, and also bandwidth utilization is also really good either for uploading or downloading, the bandwidth can be easily saturated or throttled down efficiently if you want to.

author: HighVoltage
author_rank: Super Contributor
timestamp: May 26, 2018, 01:31:47 pm
content: One benefit:The .RAR encryption is very good and can only be broken trough brute force. Try that on a 20 digit odd passphrase, it will take forever. As far as I know, all the other compression utilities have weak encryption and can be cracked within seconds.

author: BravoV
author_rank: Super Contributor
timestamp: May 26, 2018, 01:43:25 pm
content: Quote from: HighVoltage on May 26, 2018, 01:31:47 pmI guess you agree with this argument, if you really ... I mean really want a good encryption, you better not to rely only at the built-in RAR encryption, am I right ?

author: Vtile
author_rank: Super Contributor
timestamp: May 26, 2018, 05:21:40 pm
content: Why not?

author: HighVoltage
author_rank: Super Contributor
timestamp: May 26, 2018, 06:31:17 pm
content: WINRAR is using128bit AESencryption and this is really a good and strong encryption for "normal" and quick protection.Is it the best encryption you can get?For sure not!But nevertheless it is a good and reliable encryption.If I want really good encryption, I use TrueCrypt.Even better, use WINRAR and TruCrypt together and it is probably very safeIf I need the best encryption between research friends, I am using a self builtsystem with "one time pad" and a 1GB key.

author: apis
author_rank: Super Contributor
timestamp: May 26, 2018, 06:50:18 pm
content: Quote from: HighVoltage on May 26, 2018, 06:31:17 pmYup, that is the only truly 'safe' encryption scheme, assuming you got a good (true) random number generator for the key.Otherwise it's a question of how much effort/resources you think your adversaries are willing/able to spend on defeating your protection.If a script kiddie can crack something in matter of minutes it's pretty useless. If there is no officially published method for cracking the algorithm you use (like aes128) then it's probably safe unless you are afraid of an adversary with government level resources.

author: coppice
author_rank: Super Contributor
timestamp: May 26, 2018, 07:06:13 pm
content: RAR is often useful when emailing files into or out of corporate accounts. RAR files are often not detected and deleted by the security system. I'm not sure why. They seem to pick up every other kind of compressed file bundle these days.

author: cheeseit
author_rank: Regular Contributor
timestamp: May 26, 2018, 07:45:03 pm
content: Unless you're truly skilled and have a background in cryptology you really shouldn't roll your own cryptography for anything of importance. Encryption is tough to get right without leaking information or being susceptible to a multitude of attacks beyond brute force.

author: HighVoltage
author_rank: Super Contributor
timestamp: May 26, 2018, 10:42:02 pm
content: Quote from: cheeseit on May 26, 2018, 07:45:03 pmEncryption to me is like a real "Fire Safe", it is only safe for a certain temperature and time but eventually it will get hot inside.Cryptography has been only a hobby for me for many years, not a profession.But I have tried to crack some protected RAR files with no success, as long as the passphrase is long and complicated enough. Well, if a government powered brute force is used, I have no idea how long they would need on a RAR file?But, there is not too much encryption software that we can really trust.Probably the last good one was PGP in the last DOS version.Using one time pad is not that difficult.It all comes down to a truly random key.And if you make that key 1GB is size, people have to go through a lot of effort to get that key from you.You just have to hide the key very well and do not exchange it over the internet.

author: Kjelt
author_rank: Super Contributor
timestamp: May 26, 2018, 11:01:14 pm
content: With a one time pad there is no hard randomness condition for the key, like it has to have ultra high entropy or such, other than that it is unique, can't be easily guessed or social engineered. So yeah it should not be a logical sequence or have short repetition intervals but it also does not need to be extremely random.You only use each byte of the pad once in contrast to normal crypto where you use the key each time.

author: mariush
author_rank: Super Contributor
timestamp: May 27, 2018, 02:45:03 am
content: Quote from: BravoV on May 26, 2018, 07:21:48 amscene and piracy and stuff is closed - groups upload to servers they control and to which only few members have access.What you see on torrents is stuff that gets spilled (leaked) to public - some of the people that gain an account on such private servers by donating money or hardware copy the data to other servers, create torrents and put the torrents on their torrent sites.QuoteTorrents work well for public distribution, because you make the data available and as soon as a person downloads a chunk from you, that person announces to the swarm that they can upload that chunk to other people and no there's two persons offering that chunk, so you're less overloaded and can serve other chunks to the swarm instead of sending same chunk to n people. It saves bandwidth, and speeds up distribution.But when a release is pushed by piracy groups, they more or less only care to push it to "scene server" and have their "release" registered and be credited for being the first with that release.But the data is still split in chunks of up to 16 MB if i remember correctly, and each chunk is hashed with a relatively weak algorithm, and then there's communication between you and all the peers that want to download stuff from you which can use a bit of bandwidth.. so yeah, it has the benefit of recovery as once a checksum fails, the client downloads a subset of that chunk (up to 16 MB) and checks again, so unlike ftp it can correct data at any point.anyway... ftp isn't that bad... and nowadays there's also sftpQuotewell, i would think tar and tar.gz and tar.bz2 are too uncommon for Windows folks.I think in a while there were issues with zip in Linux just like there was controversy with GIF and patents and copyright but I don't think this is a reason for not liking zip... oh and nowadays there's also extensions which make zip not so compatible, just like rar5 archives ... anyway see :https://en.wikipedia.org/wiki/Zip_(file_format)#Strong_encryption_controversy7zip is fairly new and while it's open source it still needs to be downloaded and installed and the interface is kinda ugly.In contrast, rar has nice shareware application and they also offer free unrar library and source code (not open source but free to use) which can be used to legally offer decompression of rar archives in Linux and Windows (that's how 7zip and Total Commander (and other file managers) and Winace when it was popular and other compression software supported decompression of RAR archives)RAR has benefits over regular zip, like solid compression and higher dictionaries which increase compression saving disk space and bandwidth.7zip offers solid compression but i personally found it's more sensitive to corrupted data ... even with solid compression enabled, with rar archives i'm often able to unpack some files, while with 7zip one bit corrupted and no data can be recovered (if there's no error recovery data in the archive)I do use 7zip and don't install Winrar nowadays simply because Total Commander has support for 7zip and rar and zip and others built in, so i can handle them without using programs. I use 7zip to create archives only.For Rigol, it could also be a regional thing, maybe RAR is more popular in Asia ... maybe 7zip's localization is worse for Asian countries and that could be enough for people to not like it there.

author: Falkra
author_rank: Regular Contributor
timestamp: May 27, 2018, 08:32:17 am
content: Recovery record (as said before) is a good point, and the solid archive method : it treats several or all files within the archive as one continuous data stream, which can be interesting with many small files (it's not recommended if you need to extract one single file though or update the archive frequently since the whole data stream has to be read/written).

author: b_force
author_rank: Super Contributor
timestamp: May 27, 2018, 01:41:59 pm
content: In fact, splitting files is very useful when sending a lot of data over.I travel a lot and internet and wifi isn't always stable everywhere.Splitting a file make a huge difference if something goes wrong.Unfortunately the "resume" option when downloading bigger files doesn't always work.For this reason it also works well for torrents, newgroups and all that kind of stuff.

author: marshallh
author_rank: Unknown
timestamp: May 27, 2018, 06:00:44 pm
content: RAR has very good packing ratios, is quite fast with compression/decompression, and can be encrypted securely, along with recovery records to correct for media failures.7zip has good compression ratios, but loses to RAR on the other things.

author: GlennSprigg
author_rank: Super Contributor
timestamp: June 02, 2018, 12:10:33 pm
content: Quote from: HighVoltage on May 26, 2018, 10:42:02 pmI don't know anything about 'TAR-balls' etc, as everything I know about a 'Mac' I could write on the back of a matchbox !!'ZIP' files/handling is now 'built-in' to Windows, almost too MUCH so !!!.... It shows 'contents' of a Zip as though you are lookingat a normal Windows Folder/Tree/File/View... (Try telling my 'missus' she is looking inside a Zip !!!).Encryption types obviously vary, between applications. There WAS a back-door that COULD be exploited for certain OLDER '.Rar'files, that allowed cracking software to get under the hood & extract. However, that has now been corrected, and will NOT worknow unless you are working with an 'old' .rar compression/encryption..RAR files are TODAY, almost synonymous with 'pirating' sites, to simply "go against the 'man'", ie .Zip files !!! Simple as that.I too have, (just for fun!), 'played' with every legal/illegal Tool known to humankind, to 'crack' certain encryptions, that goway past the usual boring 'dictionary' attacks, (and I have Giga Bytes of Dictionaries/phrases beyond common thought!).ALL need many computers taking many weeks or months for anything but the simplest of 'passwords'. (Obviously!).However, there is ONE 'approach' that works every time for me, in a matter of 5 or 10 mins !!!!!!!.....RAR (and all other types), of files TYPICALLY contain MANY files... (although not always). And OFTEN... (let's say Pirates!),have at least ONE 'file' that is often/always repeated, in inclusion with what ever else. This can take many forms, from a200/500 byte 'speil' about their main site, and/or logos, or a common 'Thanks' to who ever.....NOW, as long as you have an un-encrypted COPY of ONE of those common files, you are home & hosed.....Because you NOW have something to COMPARE, the software I use will analyze the encrypted .RAR, against a KNOWN filenameand content, and will quickly find a 'KEY' to the encryption. This is NOT the 'password', but is a KEY that will allow, duringthe 2nd pass, to re-write the original .Rar file but without ANY encryption.... 5-10 mins max

author: helius
author_rank: Super Contributor
timestamp: June 02, 2018, 04:45:52 pm
content: What you're describing is a known-plaintext attack. If the key can be derived from knowing the plaintext, the cipher scheme is actually weak and not strong. The ZIP encryption is like this (the ZIP archive format is such that encrypted files contain known plaintext based on their name and length).

author: GlennSprigg
author_rank: Super Contributor
timestamp: June 04, 2018, 01:03:00 pm
content: Helius .... Hi there. Yes I'm aware it is called a "plaintext" attack in decryption 'circles', but I was hesitant to mentionthat, as some people get the wrong idea what is meant, behind the scenes, so I decided to 'partially' describe it.....You did say that......."If the key can be derived from knowing the plaintext, the cipher scheme is actually weak and not strong"....For those (not you!), not familiar with the numbers.... (and putting aside 'Dictionaries/phrases'), that a so-called'Brute-Force' attack, (trying every possible combination of letter & numbers including case-sensitive letters), thena relatively simple 4 or 5 character 'Password' like.... MuM2, or WiFe01 would literally take 5 or less seconds.A 7 or 8 character 'password' like.... 'JorDan22', or 'XyX911ab' may take between 6 hours and say 18 hours !!(We are talking about fast computers, NOT just 'fast' in themselves, but the 'parsing/testing' for the 'file').OBVIOUSLY, when you get into 'passwords' like..... "MygraNNYisLOvelly010101" etc, you are now into MANYweeks, not just days !!!!!!So, back to my original point, (plaintext), I have orchestrated demo tests using 'such' individual files of knownname/content, along with numerous other files/directories, all encrypted into a single '.Rar' file, and have evenused a 'Password' like..... This01Is02A03Long04PasswordBlaaBlaa .....And it STILL found the KEY (using that attack), in less than 30 mins !!!!!.....I 'note' the multi-digit/character "KEY", and use it on the 2nd pass, (in a special mode now), and almost straightaway I have a copy of the original encrypted '.Rar' file, unencrypted.....I'm only relaying what I have found..... (With THIS software)

author: apis
author_rank: Super Contributor
timestamp: June 04, 2018, 05:07:39 pm
content: Quote from: GlennSprigg on June 04, 2018, 01:03:00 pmWhat software is that if I may ask?

author: GlennSprigg
author_rank: Super Contributor
timestamp: June 06, 2018, 02:37:00 pm
content: Quote from: apis on June 04, 2018, 05:07:39 pmI'm reluctant to mention, mate, as it's relative to a professional enterprise package designed for forensics & law-enforcement.It works 50 to 100 times as fast as general commercial software, and much more powerful/diverse in functionality.... (PM me)