AAPR, is a small utility that can help you recover password of encrypted archives. At present It only support RAR v3 with encrypted file names. It can perform 2 types of recovery methods : brute-force and dictionary.
AES is a very computationally intensive encryption scheme. Because there are no known flaws that could help speed up the process, the only simple way to to find the password is to try them all. It could take a very long time. If it's a long password, It won't be possible to recover it because it would take hundreds of years of CPU time to find it.
AAPR will hence only be useful is the password is weak : short, or a word in a dictionary.
If you already know some information about the password, AAPR could be very useful : I originally wrote the program because I had to open an archive I created a long time ago but could not remember the password. Because I don’t want to have too many passwords to remember (I remember quite a lot of them already), one thing I often do, is to combine several passwords I already know to create a stronger passwords. So I have been able to use AAPR successfully by compiling a list of all the passwords I thought I could have used, and telling AAPR to try all permutations.
Old binaries found here : http://aapr.sourceforge.net/index.html
You can try to find a password by trying all the passwords combinations made up of a specific character set. If you don't know anything about the password, that would likely be at least the alphabetical lower-case characters and the numbers.
To do that you must first, create a text file that contains the characters you want to include in you character set :
- open a text editor.
- write all the characters you want on the first line.
- save it.
ex : charset.txt : abcdefghijklmnopqrstuvwxyz1234567890
Then launch aapr with the following command :
aapr -mb [charset filename] -p 7 [encryted rar filename]
-p 7 means that AAPR will try all passwords up to 7 characters in length.
The brute-force attack method allows you to form password with character string instead of single characters. This is useful when you suspect that a password is combined of known elements but don't know which.
To use that feature, just create a file containing each elements on a new line :
ex : string_set.txt: word1 word2 word3 ...
Type the same command : aapr -mb [charset filename] -p 7 [encryted rar filename]
Here -p7 means that it will try all the passwords formed with the concatenation of the words in the [charset_filename] up to 7 elements.
With this simple method, you need to use a text file containing a list of words (one per line), and the software will try each word as a potential password until the list ends.
This is a useful method to try to find weak password in a limited time : you should be able to test half-a-million words in about 12 hours.
To launch such an attack : aapr -md [dictionary filename] [encryted rar filename]
Automatic Progression Saving :
By default AAPR will save its progression every 1500 tests by writing to a .crk file with the same name as the archive. This allows you to stop AAPR at any time and be able to start it again later.
To restart a previously started job type : aapr -c [encrypted rar filename]
You can specify your own saving interval with the -t options.
ex : aapr -md [dictionary filename] -t 2000 [encryted rar filename] This will save every 2000 tries instead of the 1500 default. Warning : if you want to change the settings on a previously launched decryption attempt, you need to delete de .crk file associated with the archive you are looking to decrypt. Otherwise, it will just continue the previous attack.
Benchmark :
If you want an idea of how long a particular job will take, you can use the benchmark feature. Type all the options like you would to start the actual job but add the options -b followed by a limit of password to try.
ex : aapr -md [dictionary filename] -b 1000 [encryted rar filename]
AAPR will then stop after 1000 try and tell you how fast things are going.
Note : if you specified more than the saving limit, don't forget to delete the .crk file to start the real calculation.
Index Range :
You can start at any point in the password space you are trying.
If you are trying to find a password with a character set of 10 characters and with a maximum length of 5, there are 66429 possible password.
You can tell AAPR to start looking a the #-th password and stopped at the #-th password in the list of possible passwords using the -i option.
ex: aapr -md [dictionary filename] -i 3000 5000 [encryted rar filename]
AAPR will only try passwords between the 3000th and 5000th words in the dictionary list.
This feature is useful if you want to split the work load on several computers to speed things up. You could also use it to launch 2 instances of AAPR on the same machine in case you have a multi-core/processor machine as AAPR is at present single threaded. Finally this is also how the resuming from previously started job works : AAPR save the current index in the .crk file with the others settings.
Note : you can find out the number of possible passwords with you chosen settings using the benchmark feature to find out how to split the work.
Note : when launching several instance of the application, note that you don't need to copy the full RAR file several times : the utility only uses the first few thousands byte of the Rar files so you can use a hexadecimal editors to copy just the beginning of the file instead of having multiple copies.
Test function
Finally there is a hidden testing function to check that the utility is working properly on your computer : type aapr -?
If an error message comes up, please send me a mail at glachesis at users.sourceforge.net
Remember that any passwords that is long enough and not present in a dictionary will not be found in a reasonable time with this utility and there is nothing that can be done.
Why does it says that my RAR file is not supported ?
Probably because the block headers which contains data such as filenames are not encrypted. If the archive was not created with the option "encrypt filenames", then it's not yet supported. A test you can do to see if the file names are encrypted or not is to open the file in Winrar. If it display the list of files, then it's not supported. If it ask you for a password straightway, then you should be able to use this utility. Will you support v2 RAR archive ?
Probably not. Will AAPR support file whose filename are not encrypted ?
Maybe. I would like to but it's massively more difficult to do since in that case you must uncompress the encrypted file to know if your password is correct or not. I would need to add a Rar unpacking function. There is such a library at http://www.unrarlib.org/ that I could use but it does not support RAR v3. If they add support, I'll add this feature. Why is it so slow ?
This utility aim at recovering password for AES encrypted archive. However AES is very computationally demanding and each tries requires a lot of work by the computer. For a brute-force attack, the number of password tested by seconds could be between 10 and 30. If the password is long, then it could take very long. There is nothing that can be done. I recommend to always try a dictionary attack before falling back to brute-force.
The utility is licensed with the General Public License v3.