Data error in encrypted file 'file.7z' Wrong Password?" "File.7z

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David
2014-07-01
2014-07-02
  • David

    David - 2014-07-01

    •7-Zip version and type (32-bit / vers 7z920 )
    •Windows version and type Windows 7 Ultimate SP1 (32-bit)
    •CPU type Genuine Intel (R) CPU U7300 @ 1.30 GHz
    •RAM size 2.00 GB (1.87 GB usable)

    Created a database of 7zips and deleted originals. New to data archiving and idiotic I know. Thanksfully most archives that were burnt to disc were good. Except for two archives. They were all password protected and with default 7zip settings on compression, up to date 7zip (7z920)version. When opening the archives I was able to extract certain folders that decompressed so that there are only a couple of folders remaining that would not decompress in these archives.

    Everything else has been squared away and the removable files have been salvaged from these archives, however the remainder is sizeable, the archives created and the files inside are fairly important and mostly irreplaceable, I know, I put myself in this situation. The error that shows up upon extract or test is as the title suggests "Data error in encrypted file 'file.7z' Wrong Password?" "File.7z" has been placed instead of the file name.

    The password worked fine on the rest of the archive and from what I have gathered online it appears that these remaining files may be corrupt. Is there anything I can do to recover these files? Any advice is greatly appreciated. I apologise if this topic is covered else where.

     
  • Igor Pavlov

    Igor Pavlov - 2014-07-02

    There two possible reasons:
    1) Wrong password
    2) Corrupted data

    You can call

    7z t a.7z > test.txt
    7z l a.7z > list.txt

    if there is some "OK" file in "BAD" solid block, then it's "Corrupted data" case. In that case it's difficult to recover data.

    How to recover corrupted data.
    You must find exact place of corrupted data. Then you must find another copy of file that was compressed in that place. Create another copy of .7z arechive with same solid block including that "GOOD" copy of "bad" file with same settings. And replace "BAD" data with new "GOOD" data.

     
  • Melano Chole

    Melano Chole - 2017-03-22
    • 7-Zip (A) [64] 9.20
    • kubuntu 14.04 64 bit

    Hello! I found this thread having experienced the same problem. I create an archive with a command

    7za u -m0=LZMA2 -p -mhe=on -x!xcf/. myarc.7z myfiles/

    ...key in a password, let's say, '111' and get a normal archive that I can extract and test without any problems. The next steps corrupt data in the myarc.7z:

    1. Some new files are added to the directory myfiles/
    2. The archive myarc.7z is updated with the same command as above, but with a NEW password ('222' for instance) for the updated archive.

    Then, if I test the resulting archive with 7za t myarc.7z , I get the following:

    Testing myfiles/18.TXT Data Error in encrypted file. Wrong password?
    Testing myfiles/19.TXT Data Error in encrypted file. Wrong password?
    Testing myfiles/2.TXT
    Testing myfiles/20.TXT

    Where the files marked with "error" were packed with the password '111' , and "non-error" files are those packed with '222'. Then, if I update the archive with no files added to or removed from myfiles/ dir, but with the password '111' again, I get vice versa:

    Testing myfiles/2.TXT Data Error in encrypted file. Wrong password?
    Testing myfiles/20.TXT Data Error in encrypted file. Wrong password?
    Testing myfiles/18.TXT
    Testing myfiles/19.TXT

    If I just update the initial archive with a new password ('222' instead of '111') without any files changed, all of them get marked 'Data error...'.

    Therefore, updating an archive with a new password causes the initially packed data unavailable, while the names of the lost files could still be retrieved.

     
    Last edit: Melano Chole 2017-03-22
  • Igor Pavlov

    Igor Pavlov - 2017-03-22

    it's old version of 7-zip.
    Use latest version of 7-zip instead.

     
  • Melano Chole

    Melano Chole - 2017-03-22

    Thank you for the prompt reply, Igor.
    I've just tried the same procedure on lubuntu 16.04 (64-bit) with a manually installed p7zip-full & p7zip of 16.02 [64] version (as lubuntu 16.04 still comes with 9.20) and obtained the same result: files packed the first time become unavailable after updating an archive with a new password.

     
    • Igor Pavlov

      Igor Pavlov - 2017-03-22

      Describe all steps again with new version 16.02.
      Use simple commands.

       
  • Melano Chole

    Melano Chole - 2017-03-22

    OK, here is my experiment with 16.02 version:

    • Create an arcive of two files in a dir:

    7za u -p -mhe=on myarc.7z myfiles/ using a password '111'

    • Add two files into myfiles and use the same command:

    7za u -p -mhe=on myarc.7z myfiles/

    When it asks for a password for the 1st time, type '111'. When it asks for a password for the 2nd and the 3d time, type '222'. The compession ends with "Everything is OK" string.

    • When invoke 7za t myarc.7z and input the password '222', get a message (copy here in full):

    7-Zip (a) [64] 16.02 : Copyright (c) 1999-2016 Igor Pavlov : 2016-05-21
    p7zip Version 16.02 (locale=ru_UA.UTF-8,Utf16=on,HugeFiles=on,64 bits,1 CPU Intel(R) Pentium(R) CPU G3220 @ 3.00GHz (306C3),ASM)

    Scanning the drive for archives:
    1 file, 1031 bytes (2 KiB)

    Testing archive: myarc.7z

    Enter password (will not be echoed):

    Path = myarc.7z
    Type = 7z
    Physical Size = 1031
    Headers Size = 263
    Method = LZMA2:21 7zAES
    Solid = +
    Blocks = 2

    ERROR: Data Error in encrypted file. Wrong password? : myfiles/1.TXT
    ERROR: Data Error in encrypted file. Wrong password? : myfiles/2.TXT

    Sub items Errors: 2

    Archives with Errors: 1

    Sub items Errors: 2

    After this, the files 1.TXT and 2.TXT could not be unpacked, the files 3.TXT and 4.TXT (added on update) are retrieved normally.

    As I understand, the reason is the changed password. If type '111' on update, no problems arise. The mere ability to key in a different pass on update misleads, 7zip either should not allow to do this at all, or do that without a corruption of data.

    If invoke the above command without -p option, it asks for a password only once, but the headers get visible after such an update.

     
    Last edit: Melano Chole 2017-03-22
  • Melano Chole

    Melano Chole - 2017-03-22

    At least, I found a solution how to retrieve unavailable files if the archive was updated with a new password:

    1. Update the archive with the command like: 7za u -p -mhe=on myarc.7z myfiles/ No new files should be in myfiles. If in doubt, just specify an empty directory instead myfiles/.
    2. When it asks for a pass for the 1st time, type the LAST one you used on REAL repack.
    3. Then, when it asks for a pass for the 2nd and the 3d time, type THE PREVIOUS key you used BEFORE you changed it.
    4. Voila, the 'error' files are available to unpack. Those ones that were added with a new pass get 'error' though, but you can unpack them before the procedure )
     
    Last edit: Melano Chole 2017-03-22
  • Igor Pavlov

    Igor Pavlov - 2017-03-22

    Yes, two requests for password are possible in some cases.
    Later I'll look the code.

    Now you can use "u" without "-p" switch.
    So it will request password only one time.

     
    Last edit: Igor Pavlov 2017-03-22
  • Melano Chole

    Melano Chole - 2017-03-22

    Yes, using "u" command without "-p" switch was the first thing I tried out, and it worked. However, "-mhe=on" switch didn't work in that case; all file names became visible. Will appreciate yuor code revision. Please, tell here if you fix it. Thanks!

     
  • Igor Pavlov

    Igor Pavlov - 2017-03-22

    New version 16.02 keeps header encryption even without -mhe.

    7z u a.7z file.txt
    
     

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