In Windows 7, you can easily send files and folders to Compressed (zip) folder to generate the industry standard compressed file in Zip format and secure them by Encrypting them in EFS format but frankly it’s not quite practical to deal with Zip files which often are accessed by other parties. And when an EFS-encrypted file needs to be accessed outside the organization, exchanging the digital certificate isn’t something that is easy to do.
You can also try out WinRAR and WinZIP, the two arguably the most popular file archiver, but none of them are completely free. Yes, you can basically use them for free but in reality they are both shareware that you should pay for license if you intended to use them in a long run.
7-Zip is another popular file archiver but is an Open Source that can be used on any computers including a computer in a commercial organization without paying a dime. One of the nice things about it is that the encryption that is built in the software is very easy to use and highly secured with AES-256 encryption method.
7-Zip adds a series commands in to the context menu after it’s installed on the computer to make your life easier when it comes to zip the files.
To encrypt the final zip file during the compress process, you can simply highlight the files and folders you want to compress, right-click on any of those, and choose 7-Zip to Add to Archive.
Then in the Add to Archive dialog window, select the Archive format, put in the password, make sure the Encryption method set to AES-256 before pressing OK.
Different archive format offers different encryption methods, since AES-256 is the highest method when it comes to encrypting the data, make sure you use it to take the most advantage out of it.
To encrypt a Zip file, you will need to right-click the file, go to 7-Zip, and choose Add to Archive. I would hope the program can encrypt directly to a zipped file without adding it to another compressed file but I guess there might be limitations there that prevent the program from encrypting it directly.
Note that making a use of encryption doesn’t mean that you can provide a weak password. You are still vulnerable to the password attack if you choose a password like “abcdef” or “123456” to encrypt a highly confidential compressed zip file. The bottom line is whenever you see a place where it requires a password, picking up a good password that is tough to the hackers but still easy to remember to yourself.