RAR Archive (.rar)
RAR5 StandardRAR Archive (RAR) is a proprietary compressed archive format developed by Eugene Roshal, renowned for its tight compression, multi-volume splitting, AES-256 encryption, and Reed-Solomon recovery records.
Convert RAR to ZIP
Free in-browser RAR to ZIP converter. Convert files instantly on your device.
Inspect & Metadata
Operating systems and file analyzers identify RAR files by inspecting the leading binary byte sequence:
Byte-Level Header Signature (Magic Bytes)
Operating systems and file analyzers identify RAR files by inspecting the leading binary byte sequence:
HEX SIGNATURE (OFFSET 0):
52 61 72 21 1A 07 00 / 01 00ASCII REPRESENTATION: Rar!\x1a\x07..
Standardization: RAR5 Architecture Specification
Technical Specifications
| Container Architecture | Variable-length block header architecture with RAR4 (0x00) and modern RAR5 (0x01 0x00) specifications |
| Compression | Proprietary LZSS-based compression with large sliding dictionary (up to 4 GB in RAR5) and Huffman coding |
| Byte Endianness | Little-Endian (Intel x86) |
| Color Spaces | N/A (Archive Container) |
| Channels & Structure | Multi-file directory hierarchy, solid archives, multi-volume split parts (.r00/.part1.rar) |
| Max Dimensions | Practically unlimited (up to 16 Exabytes in RAR5) |
| Transparency | Full NTFS alternate data streams, Unix permissions, and precision timestamps |
| Streaming & Progressive | Header records distributed throughout container; non-streamable without full volume set |
Technical Comparison Matrix: RAR vs Competitors
| Technical Attribute | RAR (Current) | 7Z | ZIP | TAR.GZ |
|---|---|---|---|---|
| Recovery Records | Native Reed-Solomon error correction | None built-in | None built-in | None built-in |
| Licensing | Proprietary (commercial creation) | Free Open Source (GNU LGPL) | Open Public Domain | Free Open Source (POSIX) |
| Encryption | AES-256 with PBKDF2 / Blake2sp | AES-256 with SHA-256 | ZipCrypto (weak) or AES-256 | None (requires GPG/OpenSSL) |
| Multi-Volume Splitting | Industry pioneer in split volumes | Supported in 7z volumes | Supported in spanned ZIPs | Requires Unix 'split' tool |
Common Corruption Modes & Hex Recovery Guide
WinRAR reports 'Checksum error in the encrypted file' or CRC failed.
Root Cause: Damaged sector on storage drive corrupting compressed data bytes.
Recovery: Execute 'Repair archive' in WinRAR or File2File to reconstruct blocks using embedded recovery records.
Security Analysis & Parser Attack Vectors
RAR parsers have historically been high-value security targets due to path traversal vulnerabilities in older unrar engines.
Known Attack Vectors
- Path traversal (directory traversal) vulnerabilities writing files to arbitrary system paths (e.g. CVE-2018-20250).
- Out-of-bounds write in legacy ACE archive decompression libraries embedded in WinRAR.
- Buffer overflow when parsing malformed RAR5 volume headers.
Defensive Best Practices: Extract RAR archives using modern, memory-safe sandboxed WebAssembly engines with strict path normalization.
Historical Origins & Milestones
Key Advantages & Pros
- Integrated Reed-Solomon recovery records allow repairing damaged or corrupted archives with missing sectors.
- Multi-volume split archives (.part1.rar, .part2.rar) make distributing massive files across multiple media seamless.
- Powerful solid compression achieves superior reduction on groups of similar files.
Technical Limitations & Cons
- Proprietary format: creating RAR files requires a commercial WinRAR license or authorized RAR compressor.
- Extraction libraries (unrar) are source-available but subject to non-reverse-engineering license terms.
- Decompressing damaged solid archives without recovery records can corrupt subsequent files in the stream.
Interesting Technical Trivia
- RAR stands for 'Roshal Archive', named after its inventor Eugene Roshal.
- The magic bytes for classic RAR4 are 'Rar!\x1a\x07\x00', while modern RAR5 uses 'Rar!\x1a\x07\x01\x00'.
- WinRAR's trial pop-up reminder became an internet legend, as the software famously continued functioning indefinitely after 40 days.
Frequently Asked Technical Questions
What is a RAR recovery record?
A recovery record is optional redundant data using Reed-Solomon error correction that allows WinRAR to physically reconstruct damaged archives even if parts of the file are corrupted.
Can I open RAR files without buying WinRAR?
Yes. Windows 11 now extracts RAR files natively, and File2File.app can extract and convert RAR archives for free right inside your web browser.
What is the difference between RAR4 and RAR5?
RAR5 is the modern version of the format introduced in 2013, featuring larger dictionary sizes (up to 4 GB), stronger AES-256 encryption, Blake2sp checksums, and faster multi-core decompression.