| Feature | RAR5 | Legacy RAR | |---------|------|-------------| | Key derivation | PBKDF2-HMAC-SHA256 | Custom (weak) | | Iterations | 32768+ | 1 | | Salt | 16 bytes | Optional/weak | | AES key length | 256 bits | 128 bits | | Resistance to GPU cracking | High (due to SHA256 & iterations) | Very low |
| Feature | RAR3 (Legacy) | RAR5 (Modern) | | :--- | :--- | :--- | | | PBKDF2 with SHA-1 | PBKDF2 with SHA-256 | | Iterations | 1,024 (variable) | 262,144 (Fixed) | | GPU Attack Speed | ~200,000 hashes/second (RTX 4090) | ~6,000 hashes/second (RTX 4090) | | Salt length | 64-bit | 128-bit |
The RAR5 password hash is not a hash in the traditional sense (like MD5 or NTLM). It's a that stores only the salt and encrypted verification data. Its use of PBKDF2-SHA256 with 32K iterations makes it vastly more secure than old RAR formats. For security professionals and forensic analysts, understanding RAR5's structure is essential for recovery operations. For everyone else — if you use RAR5 with a strong, unique password, your data is safe from all but the most determined (and well-funded) attackers.
Previous versions of RAR utilized a proprietary encryption algorithm based on a 128-bit key length. While innovative for its time, the aging algorithm eventually fell prey to the advancement of GPU (Graphics Processing Unit) processing power. The key derivation function (KDF) used in older RAR versions was relatively fast, meaning modern hardware could attempt billions of password guesses per second. This rendered low-complexity passwords essentially useless against determined attackers.
In a digital forensics context, RAR5 hashes are often extracted for recovery purposes. They usually follow a specific format when exported by tools like rar2john . A typical RAR5 hash string looks like this:
: RAR5 is "intentionally slow," requiring roughly 32,768 iterations of the hash function (compared to standard SHA-256 which is nearly instantaneous). Early Rejection
RAR5 represents a significant leap in archival security. By utilizing a high iteration count and the SHA-256 primitive, it effectively shifts the advantage from the attacker back to the user, ensuring that only extremely strong, complex passwords—or vast amounts of time and energy—can penetrate the encryption.
Verdict: RAR5 is resistant to brute-force. You use a wordlist (Dictionary attack - mode -a 0 ) with good mangling rules.
When a user sets a password on a RAR5 archive, the file does not simply store the password or a basic hash of it. Instead, it initiates a complex Key Derivation Function (KDF). The RAR5 specification relies on (Password-Based Key Derivation Function 2) using HMAC-SHA256 as the underlying pseudorandom function.