RAR3 — Hashcat Mode 12500
TL;DR — RAR3 (the legacy RAR format used by WinRAR through version 4.x) uses AES-128 with a custom multi-round SHA-1-based key derivation function. The KDF is intentionally expensive — per-password verification is slower than ZipCrypto or WinZip AES — but recovery is still feasible for typical human passwords.
RAR3 cryptographic design
RAR3 (released ~2002) introduced strong encryption based on AES-128 in CBC mode. The key derivation is a custom multi-round SHA-1 chain — about 262,144 iterations of password+salt+counter through SHA-1.
This was relatively aggressive for its time and remains expensive on modern GPUs. Per-password throughput is 100x-1000x lower than for ZipCrypto or WinZip AES.
The cipher itself (AES-128) is sound — there are no known practical attacks. Security depends on the KDF cost forcing slow brute force, plus password complexity.
Recovery feasibility
Despite the relatively expensive KDF, RAR3 recovery is feasible for typical human passwords (8-12 characters, dictionary-based, year+word patterns). Modern GPU clusters complete searches within tractable time.
Strong random passwords from password managers (14+ chars, full character set) are typically not recoverable.
RAR3 archives in 2026 often come from 2002-2013 era backups, software distributions, and content archives.
RAR3 vs RAR5 (mode 13000)
RAR5 (mode 13000), introduced in 2013, redesigned the encryption to use PBKDF2-HMAC-SHA256 with much higher iteration counts. RAR5 is categorically harder to recover than RAR3 at equivalent password strength.
Frequently Asked Questions
Is RAR3 still in use?
How do I tell RAR3 vs RAR5?
Why is the KDF so slow?
Related references
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