PeaZip, like any archive management utility, needs the user to provide
the correct password to work on encypted
archives
extraction, in order to access and extract encrypted files,
and in some
cases even to list the content of the archive - i.e. if sender used
"encrypt filenames" option (7Z archives) making archive table of
content unreadable without providing correct password.
Read more about how to open
7z rar tar zip archive files, as well as using PeaZip to open
unsupported files extensions.
Recover lost /
forgotten
password
The person who created (and
encoded) the archive is the only one
to know the decryption password, and the only one that should be
contacted to
retrieve the
password in case it has been lost or forgotten by the recipient - or to
provide a non-encrypted "unlocked" version of the file, if password
cannot be recovered.
Current
revisions of mainstream archive formats like (7Z, ARC, PEA,
RAR, and ZIP) uses strong file encryption,
and it is unlikely to remove
password-protection by trial (or with brute
force password removal
utilities) if the password is not known or it was
forgotten.
Dictionary based
password remover tools may be more efficient than
brute-force routines in retrieving access to the locked files, but
strong passwords usually defeats the purpose
of similar programs
- randomly generated passwords, or long
passphrases using mixed case, numbers and symbols replacements (as
in Diceware rules), cannot usually get guessed & removed by such
password recovery tools.
Unlocking an unreadable
archive by attempting password recovery is
generally not a recommended solution, to find an unknown password being
a time-consuming process,
and not being guaranteed the result of retrieving access to the locked
archive.
|
Official
PeaZip packages and website NEVER
asks users a password to be downloaded / installed: if that happens
please don't
trust that package and use only official packages published on
PeaZip official domain or on reputable software distributors. |
An archive can be
unreadable for various reasons, in any case PeaZip lets the user in
full control about deciding if trying
to decrypt it:
- The archive
header is encrypted and it's not
possible to read it before providing the right password to unlock it.
7Z, ARC, PEA, and RAR file formats supports header / TOC encryption,
also known as encryption of file names.
Notably, ZIP files
does not support that
feature, so unreadable ZIP archives (which cannot be extracted
or opened for browsing archive content) are generally too corrupted to
be read, or may have file extension changed (being a 7z or rar
disguised as zip file, or even an exe file disguised as an archive),
which is a strong hint of possible forgery - in those cases the files
should not be trusted for opening and, especially, should not be
trusted for extraction. In
PeaZip's
file/archive browser you can enter the password clicking the proper
context menu entry or clicking on the padlcok icon in the status bar or
pressing F9
- The
archive may be corrupted (it can happen quite
frequently, i.e. when there is an error during a download of a file, or
due to a failure on the memory support), or be a fake file (i.e. a
non-archive file or random data renamed with archive type extension),
or in worst case it may have been purposely altered. In those cases the
files cannot (and in worst cases, should not) be "unlocked": you
will need to
retrieve an intact copy of the file: re-download it from a trusted
source or restore it from a reliable
backup copy.
Hint:
if you have to work on different
archives with the same password you will not need to re-enter it since
it will be kept until you change it or close PeaZip. If you open
different instances of PeaZip each will start with no password and can
keep a different password.
Why does PeaZip
prompts a password request?
|
In
some cases PeaZip
may not be able to browse archive's content because the file is
corrupted (either for accidental corruption or malicious manipulation):
PeaZip
will always let the user in control of chosing if entering a password
for trying to decrypt the archive any time an unreadable archive is
encountered - even if the file extension is not
usually associated with archives supporting encryption, as it can be
easily changed to trick unexperienced users. |
|
What to do with
an unreadable file
If you suspect an archive file is
corrupted you can do following things:
- when downloading a file from the web or while
saving a mail attachment, check if the download is reported to have
been completed correctly
(please note some download managers and some mail client make the file
available for users before the actual download is completed!)
- check if the size of
the archive is the one expected
- check if the
checksum/hash of the file is the one expected - some sources
reports checksum / hash of files for allowing users to perform this integrity check
- open the file with an hexadecimal editor to see
if its content seems normal or if it is higly uniform filled with
zeroes (to reduce fragmentation some downloaders pre-allocates the full
size of the downloaded file, then replaces the content with the actual
file), and to verify if the archive header is correct for the file type
declared in the extension (sometimes an attacker may disguise a file
type for another changing file extension).
- try to download it again or try to find
another, more reliable source (or mirror) of the same file, see if
other online users had encountered problems with the same archive
- in PeaZip, you can try a decryption password, and you
can try listing archive's content in flat mode clicking on the
expand "plus" icon (or pressing
F6)
- finally, try
to open it with a different extraction utility that may be more error
tolerant: please note that this may not be a good solution, as
relying on less stringent error checks on the archive may result in
unexpected and undetected errors in the extracted files.
Why does some
non-corrupted files are unreadable even if files with same extension
are readable?
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Please note that some file extensions,
e.g. PAK files, can be used for various, unrelated archive formats.
PeaZip supports some of the file types using that extension, but might
as well not support unrelated archive formats using the same extension,
so it will not be able to open those files.
Other extensions, e.g. EXE, and DMG, covers very borad standards -
evolving for decades - employing a variety of packing and compression
technologies, some of them (usually legacy or very cutting edge cases)
not supported by PeaZip, which will be consequently unable to open as
archives some files of those formats.
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Read more about unreadable
files and password protection: checksum and hash functions,
encryption articles
on Wikipedia, Diceware password
generation tips.
Learn how to create encrypted 7Z
files with hidden filenames, feature which is also available when creating encrypted RAR files (if
WinRar is available on the same system). Creating encrypted ZPAQ files
filenames are always encrypted (hidden), as well as when creating encrypted PEA archives.
Synopsis: How to open
unreadable or encrypted 7z rar zip archives. Remove
password prompt. Unlock forgotten or lost passwords. Recover locked
data with forgotten password. Read corrupted files. Open password
protected encrypted files. What are nd how to detect unreadable files
due forgery or
data corruption.
Topics: open encrypted files,
unlock password protected archives, recover lost password, open
unreadable files
PeaZip > FAQ
> How to open / unlock unreadable 7z rar zip files
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