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I know the password to the RAR file as I locked it myself. Is there a way to do this in WinRAR or an equivalent program? The only thing I knew to do was to extract it, then create a new RAR without the password.

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    First, those aren't DOS commands, they're just running programs with some command-line arguments. Second, all those commands do are extract the archive, delete it, and re-compress the files again. This is the only way to do what you want, see my answer below.
    – Breakthrough
    Aug 30, 2011 at 14:50
  • What @Breakthrough said - that's just unpacking and repacking them, it even says so explicitly. This is the only way to do it.
    – Shinrai
    Aug 30, 2011 at 14:51
  • Thanks, guys! I see now. I didn't check it out thoroughly.
    – Abluescarab
    Aug 31, 2011 at 3:11
  • It's good that you're writing it's a "nice to know" question, because in the time it took you to write this you could've unpacked/repacked ;-)
    – Jan Doggen
    May 17, 2013 at 8:28

6 Answers 6

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Out of the box, no, you can not. Version 3 of the RAR file format (implemented first in WinRAR 2.9) encrypts the actual data itself, as well as the file headers (if requested) using AES-128 encryption. With just WinRAR, it is impossible to simply "remove" the password from an archive, since the data itself is encrypted with the password.

You could make a quick batchfile implementing a "remove password" feature, which could simply unrar the archive, and then re-compress the files without a password.

Technically, the data is compressed before being encrypted. This indicates that, given enough knowledge of the RAR file format itself, one could create a tool to AES-decrypt the datastream of the compressed files, and then save it into a new RAR archive. It should be noted, however, that this requires extensive knowledge of the file format itself.

Given the number of open-source tools that support password-protected RAR files (e.g. unar), one could learn how to do this by reading existing source code, and then using the decrypted, but still compressed, bitstream to generate a new RAR archive. However, this is far from a trivial task, as you would then have to rebuild the RAR header manually as well (or at least ensure the file format's compatibility).

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    No, logically, it should be possible to decrypt the data without decompressing it, because it's encrypted compressed data, not compressed encrypted data. (the latter is fundamentally impossible, due to entropy increases from encryption). It's just an obscure enough thing to want to do that it's omitted.
    – Random832
    Aug 30, 2011 at 18:00
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    Right. If he had just PGP encrypted the RAR, he could have easily decrypted it without recompressing it.
    – Scott McIntyre
    Aug 30, 2011 at 20:57
  • Well, thanks for explaining it! It's rather disappointing, because I honestly believe this should be a feature, but I suppose not enough people want this feature to justify including it.
    – Abluescarab
    Aug 31, 2011 at 3:20
  • @Random832 yes sorry, I see that was poorly worded now. I updated the answer just now to hopefully get my thoughts across a bit more clear. After further research, this does to be technically possible given enough knowledge of the RAR format... Although as you said, obscure enough to be omitted (not to mention the proprietary nature of the RAR format complicates things). However, if anyone does want to get into it, I provided a link to an example open-source tool (unar) which can decrypt encrypted RAR archives.
    – Breakthrough
    Aug 2, 2013 at 13:34
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Actually, I think a previous answer from another question already answers this:

You can do it by using this method . Tools > Convert Archives > Compression > General > Set Password > then click ok and save :)

but it re-compresses the archive.

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You have to decompress and then recompress into a new RAR file. Then simply delete the old encrypted file and you've got yourself a fresh new RAR package without the unneeded password.

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Or you can open the archive then rightclick on the file and choose "set default password" and then enter the password, this way you will never have to enter the password again anytime you want to open the file.

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Create a new unprotected RAR file (e.g. containing an empty folder), then open the old protected one.

Now drag the files into the new unprotected RAR. No extracting needed.

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Since the question How can I remove the password on several RAR files at once? was marked as a duplicate of this question, here's how to remove the password on several RAR files at once:

Step 1: uncompress all RAR archives in their own folder (1 folder per archive) at once via 7-Zip, via right-click in explorer.exe -> 7-Zip -> Extract to *\.

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Step 2: recompress each folder into their own RAR archive, select all the folders, right-click in explorer.exe -> WinRAR -> checkbox "Put each file to separate archive". Screenshot from journeybytes.com:

enter image description here

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