Rhyous

November 19, 2010

Creating or opening a password protected zip file on FreeBSD

Filed under: FreeBSD,OS X,PC-BSD — J. Abram barneck @ 5:15 am

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.

# zip -e myarchive.zip myfile1

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.

# zip myarchive.zip myfile2

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.

# zip -e myarchive.zip myfile1 myfile2 myfile3

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.

# zip -r -e myarchive.zip mydirectory

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.

# zip -d myarchive.zip myfile1

Opening a password protected zip file

The syntax for unzipping a file is a lot easier.  It uses a different binary file called unzip.

# unzip myarchive.zip

The above prompts for the password automatically and unzips the files, assuming the correct password is provided.

Advertisements

1 Comment »

  1. 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

    Comment by Francisco — November 21, 2010 @ 8:15 pm | Reply


RSS feed for comments on this post. TrackBack URI

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Blog at WordPress.com.

%d bloggers like this: