September 29, 2012 at 19:00Hello world for RAR virtual machine (RarVM)
Believe it or not, rar archives can contain a simple, x86-like bytecode for the RarVM virtual machine. This is done in order to be able to implement filters (preprocessors) in the archive for two-way conversion of input data in order to increase redundancy and increase the degree of compression.
For example, there is an Intel E8 preprocessing filter, the beginnings of which probably come with LZX, which is designed to increase redundancy in x86 code.
WinRAR includes many standard filters to increase the compression ratio for typical input data, but it also allows you to include them directly in the archives!
Tavis Ormandy - the person who found out about this, did not find any utilities for working with filters in RAR archives, and therefore wrote his own.
Read more on the Tavis Ormandy page
For example, there is an Intel E8 preprocessing filter, the beginnings of which probably come with LZX, which is designed to increase redundancy in x86 code.
WinRAR includes many standard filters to increase the compression ratio for typical input data, but it also allows you to include them directly in the archives!
Tavis Ormandy - the person who found out about this, did not find any utilities for working with filters in RAR archives, and therefore wrote his own.
Read more on the Tavis Ormandy page
