kimci86/bkcrack

Health v2 · maintenance only

Adoption not part of the score

2176 stars · 189 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

bkcrack is a command-line tool that cracks legacy ZIP encryption (ZipCrypto/PKWARE) using Biham and Kocher's known plaintext attack. Given ciphertext and at least 12 bytes of known plaintext, it recovers the keystream generator's internal state, can decrypt entries, remove or change passwords, and optionally brute-force the original password.

Use cases

• recover password from encrypted zip file
• decrypt legacy zipcrypto archive with known plaintext
• remove password protection from a zip archive
• change the password of an encrypted zip file
• crack pkzip traditional encryption
• unlock old zip file when I know part of its contents

When to choose

• you have at least 12 bytes of known plaintext for an encrypted entry
• the archive uses legacy ZipCrypto encryption rather than AES
• you want a fast, multithreaded, cross-platform CLI with prebuilt binaries

When to avoid

• the zip uses AES or other modern strong encryption instead of ZipCrypto
• you have no known plaintext and the password is long or complex
• you need a GUI-based recovery tool

Facets

cli-tool · maturity active

security cryptography penetration-testing security files privacy windows cli cross-platform zipcrypto known-plaintext-attack password-recovery zip cracking linux macos

Member repositories

For agents

markdown · JSON · MCP: product_card(name="kimci86/bkcrack")