WinZip® 9.0 SR-1 is a maintenance release of WinZip 9.0. This version of WinZip has been enhanced to warn you about some of the most common situations in which you could become infected by a virus compressed inside a Zip file. Please see Potentially Unsafe File Types for full information about this change.
Improvements in WinZip 9.0 concentrate on its core functionality: compression, capacity, and a new, advanced data encryption capability. Using WinZip 9.0, you can compress more data, compress it better, and protect your confidential information with far greater security.
Details of these and other enhancements follow.
Advanced encryption
WinZip 9.0 supports 128- and 256-bit key AES encryption, which provide much greater cryptographic security than the traditional Zip 2.0 encryption method used in earlier versions of WinZip.
WinZip 9.0's advanced encryption (FIPS-197 certified) uses the Rijndael cryptographic algorithm which, in 2001, was specified by the National Institute of Standards and Technology (NIST) in Federal Information Processing Standards (FIPS) Publication 197 as the Advanced Encryption Standard (AES).
After a three-year competition, the AES was announced by NIST as an approved encryption technique for use by the U.S. government, private businesses, and individuals. When properly implemented as a key component of an overall security protocol, the AES permits a very high degree of cryptographic security, yet is fast and efficient in operation.
WinZip's AES encryption is just as easy to use as traditional Zip 2.0 encryption: all you have to do is select the encryption strength and specify your password.
Note: recipients to whom you send AES-encrypted Zip files must have a compatible Zip file utility in order to decrypt the files. We have published the full specification for creating WinZip-compatible AES-encrypted Zip files, and we expect that other Zip file utility vendors will provide support for the format.
Greater capacity
In addition to supporting the original Zip file format, WinZip 9.0 also supports the 64-bit extensions to the Zip file format. The extended format lets you store all the data you need in Zip files of virtually unlimited size.
The original Zip file format limited the number of member files in a Zip file to 65,535, and the maximum size of both the Zip file itself and any member file to 4 gigabytes. For all practical purposes, the 64-bit extended format eliminates all these restrictions. Using the extended format, the member file size, Zip file size, and number of member files you can add to a Zip file are limited only by your system's resources.
WinZip remains fully compatible with the original file format and uses the original format whenever possible. WinZip uses the 64-bit extended format only when the limits of the original format are exceeded.
Improved compression
WinZip 9.0 supports the "enhanced deflate" compression method. This compression method provides greater compression for many types of files and reduces the size of your Zip files, saving you data transmission time and valuable disk space.
Note: versions of WinZip prior to WinZip 8.1 will not be able to extract files compressed with this new method.
A list of features introduced in earlier versions of WinZip is available from the WinZip web site at http://www.winzip.com/version.htm.