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The free, open-source 7-Zip program compresses numerous files and folders into a single archive file that’s easily transferable. If the compressed files weren’t previously compressed, such as text files, the resulting archive will be considerably smaller than the sum of each file size. However, if the files were already compressed, such as JPG images or MPG movies, you won’t conserve much space by compressing them further. But, that’s only one of the benefits of compression, and honestly, if that’s all you were after, then Windows 8’s built-in ZIP support would suffice.
One of the features that sets 7-Zip apart from Windows’ integrated ZIP utility is archive encryption, which optionally applies strong, 256-bit AES encryption to the archive. This means as long as you’ve chosen a strong password, nobody can gain access to those files without the appropriate password, even if the archive is intercepted during email transit.
When applying encryption with 7-Zip, you have two file choices: 7Z or ZIP. The ZIP format supports AES-256 or ZipCrypto encryption methods. ZipCrypto is weaker than AES-256 and may be subject to attacks, but it has the advantage of being compatible with Windows, so a recipient could open the file without needing 7-Zip himself. Using the stronger AES-256 encryption method, however, would require 7-Zip, WinZip or other supporting software to open the archive. Alternatively, the 7Z format only offers the AES-256 encryption method, but has the additional advantage of optionally encrypting file names. Therefore, if you don’t want to reveal any information about your files, you should choose the 7Z format.
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Creating an Encrypted ZIP or 7Z Archive
1. Download the 7-Zip Installer and double-click the EXE or MSI file in File Explorer to begin installing the program. Be sure to download the correct bit-type for your system. A quick way to know if you have a 64- or 32-bit system is to open File Explorer and look in the C:\ drive. If you have “Program Files” and “Program Files (x86)” folders, you have a 64-bit system. If you only have a “Program Files” folder, you have a 32-bit system.
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3. Click the “Archive Format” drop-down menu and select either “7Z” or “ZIP,” depending on your preference. If you chose “ZIP,” you can choose “AES-256” or “ZipCrypto” from the Encryption Method drop-down menu. The archive’s file name is automatically entered in the Archive field with the currently opened directory selected as the save location. However, you can change the name or location by clicking the ellipsis (“…”).
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5. Click the “Split to Volumes, Bytes” drop-down menu if you’re compressing large files and need to limit individual archive sizes. Alternatively, manually type a custom volume size in megabytes, followed by “M,” such as “100M” for 100 megabytes volumes. If the total size exceeds this value, one or more parts are created, so you can store them or email them separately.