Creating and Working with .zip files: Encryption, SFX, Splitting

In my previous post, I explain what .zip files are and how to zip and unzip a file or folder, I also explain how you can send a folder as an attachment by zipping the folder in a previous blog post. This article explains the various concepts in working with .zip files, which include File encryption, file splitting, and the Self extracting archive files (SFX).

Encrypting .zip files

While creating a .zip archive, you can be presented with the following options.

From the image above, we can see that there are options to encrypt our file, and to split it into different parts, also, toggling on the toggle bars present us with more options:

We can see the options to include passwords, and to set the encryption types to either zip standard, AES 128, and AES 256.

You may be wondering about the importance of encryption, the meaning of the encryption types, and the usefulness of splitting files, I have explained them below.

The screenshot above was taken from an android device, I have explain how to zip a file using a smartphone, please visit this link.

Usefulness of Encrypting Zip files

It is a general knowledge that email communication isn’t secure, hence sensitive data’s related via mail are exposed to the danger of getting into the wrong hands, to protect yourself from such occurrence, you can consider encrypting your zipped files before sending, especially if those files contains sensitive information.

When your zip file is encrypted, anybody without the proper authentication (I.e. whoever is not in possession of the password) cannot have an access to your zipped file

The Encryption types

Encrypting a zip file can be done by using 3 encryption types, which are the Standard Encryption, AES 128 Encryption, and AES 256 Encryption.

The Standard Zip Encryption

The Standard zip Encryption (Standard Zip 2.0 Encryption) is an old Encryption method that protects against intruders that do not have the password to a zipped file but are trying to get access to the zipped content.

This technique is weak when compared to the Advanced Encryption Standards (AES) since anyone with a specialized password recovery tool can easily gain access to the zipped contents.

Although this type of Encryption is supported by most platforms, which is its comparative advantage, it is not advisable to rely on this encryption to protect your data since it can be easily breached.

AES 128 Encryption

Advanced Encryption Standard 128, is substandard of the AES, it is an Encryption that uses 128-bit characters to conceal data by turning them to only-machine-readable texts, it is an Encryption Standard approved by the National Security Agency (NSA) to encrypt sensitive information.

The Zip file standard also includes AES 256-bit Encryption for encrypting data, but the 128-bit AES is common for AES encryption, and less secure when compared with the 256-bit AES.

Even though this type of Encryption is less secured in comparison to the 256-bit, it is also an advanced standard way of encrypting your zipped file since it can be entirely hard to crack, it is used to encrypt secret government information.

AES 256 Encryption

The AES 256 Encryption uses the AES-data-Encryption algorithm with a length of 256-bit to conceal secret information, it is the most complex of the AES Encryption technique and it is also the most secure, it is approved by the National Security Agency (NSA) to encrypt highly sensitive government information.

It will take several trillion years to crack an information Encrypted using the AES 256 technique, hence the preferred technique by institutions to encrypt highly sensitive information.

Now, that you have gotten an idea of how the various encryption works, you can choose the best encryption method to encrypt your zipped files.

To encrypt a zip file, simply input a password and choose the encryption type (the process is the same regardless of the platform used) but to decrypt the file, the recipient must have the password, and also must have the required platforms, most platforms don’t support all encryption types, so the recipient may need to download additional software

Splitting zip archives

While creating a zip file, we also had the option to split the file into volumes as can be seen in the screenshot below.

The file to be encrypted in the picture above contains a large size, we can split this file size into multipart in case we want to have them to a disc that can only hold a smaller file size, for example, I shall split the example above into ten parts by indicating the part number and the desired size for each part. (You can simply indicate the file size, and the part number will update automatically)

A similar procedure can be followed if you are using a Windows PC.

Note that to open a split file, you need a specialized zipping tool as windows cannot open a split zip file, to open the file, they must be in the same folder, however, you can encrypt your file, but you cannot create a self-extracting-archive with a split file.

Self Extracting Archive (SFX)

Self-extracting archives are zipped files ending with the .exe file extension (Microsoft file extension). Executing an SFX file will automatically launch the file without the need to undergo unzipping.

This type of file doesn’t need any special software to execute and it can utilize the .7z file extension of encrypting the names of a file. But SFX files utilizing the .7z filename encryption can only be sent to recipients that know the content of the zipped file as anyone can be skeptical to open a file which name is encrypted.

I hope you find this information useful, if you had any questions, kindly leave them in the comment box.

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