As other have alluded, 7-zip is great.
Note: I am going to zip and then unzip a file. Unzip is at the bottom.
My contribution:
Get the
7-Zip Command Line Version
Current URL
http://www.7-zip.org/download.html
The syntax?
You can put the following into a .bat file
"C:\Program Files\7-Zip\7z.exe" a MySuperCoolZipFile.zip "C:\MyFiles\*.jpg" -pmypassword -r -w"C:\MyFiles\" -mem=AES256
I've shown a few options.
-r is recursive. Usually what you want with zip functionality.
a is for "archive". That's the name of the output zip file.
-p is for a password (optional)
-w is a the source directory. This will nest your files correctly in the zip file, without extra folder information.
-mem is the encryption strength.
There are others. But the above will get you running.
NOTE: Adding a password will make the zip file unfriendly when it comes to viewing the file through Windows Explorer. The client may need their own copy of 7-zip (or winzip or other) to view the contents of the file.
EDIT::::::::::::(just extra stuff).
There is a "command line" version which is probably better suited for this: http://www.7-zip.org/download.html
(current (at time of writing) direct link) http://sourceforge.net/projects/sevenzip/files/7-Zip/9.20/7za920.zip/download
So the zip command would be (with the command line version of the 7 zip tool).
"C:\WhereIUnzippedCommandLineStuff\7za.exe" a MySuperCoolZipFile.zip "C:\MyFiles\*.jpg" -pmypassword -r -w"C:\MyFiles\" -mem=AES256
Now the unzip portion: (to unzip the file you just created)
"C:\WhereIUnzippedCommandLineStuff\7zipCommandLine\7za.exe" e MySuperCoolZipFile.zip "*.*" -oC:\SomeOtherFolder\MyUnzippedFolder -pmypassword -y -r
As an alternative to the "e" argument, there is a x argument.
e: Extract files from archive (without using directory names)
x: eXtract files with full paths
Documentation here:
http://sevenzip.sourceforge.jp/chm/cmdline/commands/extract.htm