bkcrack ☆
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Description:
Crack legacy zip encryption with Biham and Kocher's known plaintext attack
Type: Formula  |  Latest Version: 1.8.1@0  |  Tracked Since: Dec 17, 2025
Links: Homepage  |  formulae.brew.sh
Category: Security
Tags: encryption security zip forensics password-recovery cryptography
Install: brew install bkcrack
About:
bkcrack is a specialized cryptographic tool that implements the known plaintext attack against legacy ZIP encryption, originally described by Biham and Kocher. It exploits weak encryption used in older ZIP files to recover the internal encryption keys, allowing users to access protected archives without the original password. This is particularly valuable for data recovery and forensic analysis of archives created with outdated software.
Key Features:
  • Implements Biham and Kocher's known plaintext attack
  • Recovers encryption keys from legacy ZIP files
  • Supports 128-bit and 256-bit encryption variants
  • Provides detailed progress and statistics during cracking
  • Cross-platform command-line interface
Use Cases:
  • Recovering access to password-protected ZIP files when the password is lost
  • Digital forensics and data recovery operations
  • Testing the security of legacy encrypted archives
  • Migrating old encrypted data to modern secure formats
Alternatives:
  • fcrackzip – fcrackzip performs brute-force attacks while bkcrack uses a known plaintext attack, making it faster for suitable files
  • John the Ripper – John is a general-purpose password cracker that includes ZIP support, but bkcrack is specialized and more efficient for legacy ZIP encryption
License: Zlib
Bottles available for: arm64_tahoe, arm64_sequoia, arm64_sonoma, sonoma, arm64_linux, x86_64_linux
Version History
Detected Version Rev Change Commit
Oct 25, 2025 4:51pm 0 VERSION_BUMP c4d7384b
Sep 12, 2025 7:02pm 0 VERSION_BUMP 8eb72468
Dec 21, 2024 7:51pm 0 VERSION_BUMP c2d25209
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