.RAR

Introduction

RAR is the archive format of WinRAR, created by Eugene Roshal in 1993. Its compression is proprietary: only WinRAR and RAR can create RAR archives, while the free UnRAR source code lets other programs extract them. It supports solid archives, archives split across several volumes, recovery records that can repair a damaged archive, and AES encryption.

The current format is RAR 5.0, introduced with WinRAR 5.0 in 2013. Older archives use the RAR 1.5 to 4.x format, which has a different header layout.

Software

• WinRAR (Windows; RAR for macOS and Linux on the command line)
• 7-Zip, extract only (Windows)
• The Unarchiver, extract only (macOS)
• PeaZip, extract only (Windows, macOS, Linux)
• UnRAR, RARLAB’s free extractor and its source code

Structure

A RAR archive starts with a marker that also gives its version: Rar!, then 1A 07 00 for RAR 1.5 to 4.x, or 1A 07 01 00 for RAR 5.0. A self-extracting archive has a program in front of the marker.

In RAR 5.0 the rest of the archive is a series of blocks. Each block starts with a CRC-32 of its header, the header size and a header type, with sizes and types stored as variable-length integers.