symmetric-cipher-attacks
This skill covers hands-on cryptanalysis of symmetric encryption vulnerabilities across block and stream ciphers. Learn to exploit CBC padding oracles and bit flipping attacks, detect and abuse ECB mode repetition, decrypt data byte-at-a-time, and break stream ciphers through key reuse and state recovery. Includes Python implementations and tool usage for authorized testing and CTF challenges.
Symmetric Cipher Attacks teaches practical exploitation of CBC padding oracles, ECB mode weaknesses, bit flipping, and stream cipher key reuse.
AI-generated summary based on this skill's SKILL.md
Decision gist · record as of 2026-06-16
Symmetric Cipher Attacks teaches practical exploitation of CBC padding oracles, ECB mode weaknesses, bit flipping, and stream cipher key reuse. This skill covers hands-on cryptanalysis of symmetric encryption vulnerabilities across block and stream ciphers. Learn to exploit CBC padding oracles and bit flipping attacks, detect and abuse ECB mode repetition, decrypt data byte-at-a-time, and break stream ciphers through key reuse and state recovery. Includes Python implementations and tool usage for authorized testing and CTF challenges.
Use it when
- symmetric-cipher-attacks demonstrates that ECB encrypts identical plaintext blocks to identical ciphertext blocks, leaking patterns.
- symmetric-cipher-attacks covers multiple decryption techniques that don't require the original key.
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Read SKILL.md below before installing (2 files). Open directory: indexed for reading, not audited.
Install
yaklang/hack-skills/symmetric-cipher-attacks · repository language: CSS
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Frequently asked questions
AI-generated answers based on this skill's SKILL.md and metadata
What is a CBC padding oracle attack tutorial for symmetric-cipher-attacks?
symmetric-cipher-attacks teaches how padding oracle vulnerabilities work in CBC mode. When a server leaks whether padding is valid or invalid, attackers can decrypt ciphertext byte-by-byte without the key. The skill covers the mechanics of manipulating ciphertext blocks, observing server responses, and reconstructing plaintext through iterative guessing. Tools like PadBuster automate this process for authorized testing.
How does symmetric-cipher-attacks explain ECB mode weaknesses?
symmetric-cipher-attacks demonstrates that ECB encrypts identical plaintext blocks to identical ciphertext blocks, leaking patterns. The skill teaches detection methods (spotting repeated ciphertext), exploitation techniques (byte-at-a-time decryption), and why ECB should never be used. Practical examples show how to recover plaintext from ECB-encrypted data without the key through systematic block manipulation.
Can symmetric-cipher-attacks help decrypt data without the key?
symmetric-cipher-attacks covers multiple decryption techniques that don't require the original key. These include padding oracle attacks on CBC, ECB block-by-block recovery, stream cipher key reuse exploitation via XOR, and state recovery attacks on LFSRs and RC4. Each method targets specific cipher modes or implementation flaws rather than breaking the cipher mathematically.
What stream cipher attacks does symmetric-cipher-attacks include?
symmetric-cipher-attacks teaches key reuse vulnerabilities in stream ciphers, where XORing two ciphertexts encrypted with the same keystream reveals plaintext patterns. The skill covers two-time pad attacks, Kasiski examination for repeating keys, RC4 bias attacks for plaintext recovery, and LFSR state recovery through cryptanalysis. Python implementations demonstrate practical exploitation.
Is symmetric-cipher-attacks suitable for CTF and authorized testing?
symmetric-cipher-attacks is designed for both CTF cryptography challenges and authorized penetration testing. It covers block cipher mode attacks, stream cipher breaks, and cryptanalysis techniques used in competitions. The MIT license permits educational and professional use. The skill emphasizes hands-on Python implementations and tool usage for legitimate security assessment scenarios.
SKILL.md
Rendered from the published skill. Quoted content, verbatim.
SKILL: Symmetric Cipher Attacks — Expert Cryptanalysis Playbook
> AI LOAD INSTRUCTION: Expert techniques for attacking symmetric encryption in CTF and authorized testing. Covers CBC padding oracle, CBC bit flipping, ECB detection and exploitation, stream cipher key reuse, LFSR/LCG state recovery, RC4 biases, and meet-in-the-middle attacks. Base models often confuse ECB and CBC attack strategies or fail to set up byte-at-a-time ECB decryption correctly.
0. RELATED ROUTING
- rsa-attack-techniques when symmetric key is protected by RSA
- hash-attack-techniques when HMAC or hash-based authentication is involved
- lattice-crypto-attacks for LCG/LFSR state recovery via lattice methods
Advanced Reference
Also load BLOCK_CIPHER_ATTACKS.md when you need: - Detailed attack scripts
(truncated - see the full file via the links below)
File tree — 2 files
skills/symmetric-cipher-attacks/BLOCK_CIPHER_ATTACKS.md
skills/symmetric-cipher-attacks/SKILL.md
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