Last modified: 2023-03-29

Archive encryption

It is easy to protect archive with a password, however common process will not encrypt the header (which contains the tree structure with file names).

Warning

You can list contents of the archive without password.

\$ 7z l test.zip

7-Zip [64] 17.04 : Copyright (c) 1999-2021 Igor Pavlov : 2017-08-28
p7zip Version 17.04 (locale=en_CS.UTF-8,Utf16=on,HugeFiles=on,64 bits,24 CPUs x64)

Scanning the drive for archives:
1 file, 3366 bytes (4 KiB)

Listing archive: test.zip

--
Path = test.zip
Type = zip
Physical Size = 3366

   Date      Time    Attr         Size   Compressed  Name
------------------- ----- ------------ ------------  ------------------------
2022-05-11 22:12:29 .....         9399         3150  test.txt
------------------- ----- ------------ ------------  ------------------------
2022-05-11 22:12:29               9399         3150  1 files

Info

You can use p7zip program to encrypt the header information:

\$ 7za -p'password' -mhe=on a archive_name.7z folder_name
\$ 7za -p -mhe=on a archive_name.7z folder_name

Where -p'password' sets the password and -mhe=on will enable encrypting the header. If there is no string with password, user will be prompted to enter it - this way it will not be logged in terminal history.

With header encrypted, you cannot access the information without password.

\$ 7z l test.7z

7-Zip [64] 17.04 : Copyright (c) 1999-2021 Igor Pavlov : 2017-08-28
p7zip Version 17.04 (locale=en_CS.UTF-8,Utf16=on,HugeFiles=on,64 bits,24 CPUs x64)

Scanning the drive for archives:
1 file, 3215 bytes (4 KiB)

Listing archive: test.7z


Enter password (will not be echoed):

ERROR: test.7z : Can not open encrypted archive. Wrong password?

ERRORS:
Headers Error


Errors: 1