As of October 2022, BitZipper has been discontinued. Please check out our other product Bitberry File Opener instead - it can open 410 file types, including even more archive- and compressed files than BitZipper could.

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AES encryption - data security

BitZipper will not only compress and decompress files for you, it will also encrypt it with strong AES encryption!

What is encryption?

Encryption is the process of changing data into a form that can be read only by the intended receiver. To decipher the message, the receiver of the encrypted data must have the proper decryption key (password).

In traditional encryption schemes, the sender and the receiver use the same key to encrypt and decrypt data. In this case the key is the password you supply when adding files to your ZIP-file - to unzip the file the same password must be supplied.

Encryption schemes supported by BitZipper

BitZipper 4.1 and newer supports two encryption schemes, ZIP 2.0 encryption and AES encryption:

1. ZIP 2.0 encryption

Also known as standard password protected ZIP-files. This protection scheme is rather weak and tools that can 'recover' (crack) these passwords exist. All ZIP-tools support this encrypton scheme and can be used to unzip your protected files, but you should not rely on this protection scheme to protect sensitive data.

2. AES encryption

AES stands for Advanced Encryption Standard. AES is a symmetric key encryption technique which will replace the commonly used Data Encryption Standard (DES).

It was the result of a worldwide call for submissions of encryption algorithms issued by the US Government's National Institute of Standards and Technology (NIST) in 1997 and completed in 2000.

The winning algorithm, Rijndael, was developed by two Belgian cryptologists, Vincent Rijmen and Joan Daemen.

AES provides strong encryption and has been selected by NIST as a Federal Information Processing Standard in November 2001 (FIPS-197), and in June 2003 the U.S. Government (NSA) announced that AES is secure enough to protect classified information up to the TOP SECRET level, which is the highest security level and defined as information which would cause "exceptionally grave damage" to national security if disclosed to the public.

The AES algorithm uses one of three cipher key strengths: a 128-, 192-, or 256-bit encryption key (password). Each encryption key size causes the algorithm to behave slightly differently, so the increasing key sizes not only offer a larger number of bits with which you can scramble the data, but also increase the complexity of the cipher algorithm.

BitZipper supports 128- and 256-bit encryption keys, which is the two key strengths supported by WinZip 9. Both key strengths provide significantly better security than standard ZIP 2.0 encryption. It is slightly faster to encrypt and decrypt data protected with 128-bit AES, but with today's fast PCs the time difference is barely notable.


Most ZIP-utilities do not have support for AES encryption and thus will not be able to unzip files created with BitZipper 4.1 or newer. BitZipper 4.1 is compatible with WinZip 9, and both utilities can unzip AES-protected ZIP-files created by the other.

Do not rely on the encryption algorithm alone when protecting your data. Be sure you select a password or rather a "pass phrase" which is difficult to guess but still easy for you to remember. Always use a mix of lowercase/uppercase letters, digits and special characters.

Only the content of files stored in a ZIP-file is encrypted. The file name, date, size and attributes are stored in unencrypted form in the ZIP-file header and can be viewed without a password, by any tool that can access a ZIP-file.