Creating or opening a password protected zip file on FreeBSD
So this works on FreeBSD but it probably works on OS X, most Linuxes, Solaris, and other Unixes as well.
Installing prerequisites
In order to create a password protected zip file and later open it, two ports are needed:
- zip
- unzip
To install these using packages, do this as root:
| # # |
pkg_add zip pkg_add unzip |
Or using ports:
| # # # # |
cd /usr/ports/archivers/zip make install cd /usr/ports/archivers/unzip make install |
Creating a password protected zip file
There are a couple of different ways you may want to create a zip file. You may want to zip a sing file, or two or more files, or and entire directory and all its contents. You may also want to add a file to an existing zip file.
All of these actions can be done with a binary called zip.
Example 1 – Creating a password protected zip file containing one file
The syntax is simple. The -e parameter is to encrypt with a password. Always put the zip file first and the file to be zipped second.
Example 2 – Adding a file to your password protected zip file
Since your zip file already is encrypted with a password and adding a file does not require decrypting, you don’t need the password to add a file to the zip file.
Example 3 – Creating a password protected zip file containing multiple files
This is very similar to Example 1. The -e parameter is to encrypt with a password. Always put the zip file first and the files to be zipped last separated by a space.
Example 4 – Creating a password protected zip file containing a directory and all is contents.
The -r parameter is to do a recursive zip (recursive means to include the folder and all its contents). The -e parameter is to encrypt with a password. Always put the zip file first and then the directory name.
Example 5 – Delete a file from the zip
This is easier than you think. Because you are not actually reading the contents of a file in the archive, the password is not needed to delete a file inside the zip file.
Opening a password protected zip file
The syntax for unzipping a file is a lot easier. It uses a different binary file called unzip.
The above prompts for the password automatically and unzips the files, assuming the correct password is provided.
I am not sure if this has changed, but historically the encryption in the "zip" program is fairly weak.
The zip format itself has support for strong encryption.
I found this reference that may be of interest: http://www.ask.com/wiki/ZIP_(file_format)#Encryption