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Found 9 Skills
Guidance for implementing differential cryptanalysis attacks on FEAL (Fast Data Encipherment Algorithm) and similar block ciphers. This skill should be used when tasks involve recovering round keys, implementing differential attacks, exploiting cipher weaknesses, or performing cryptanalysis on Feistel network ciphers. Applicable to CTF challenges and educational cryptanalysis exercises.
Guide for performing linear cryptanalysis attacks on FEAL and similar Feistel ciphers. This skill should be used when tasks involve breaking FEAL encryption, recovering cipher keys using known plaintext-ciphertext pairs, or implementing linear cryptanalysis techniques. Applies to cryptographic challenges mentioning "linear attack," "FEAL," "Feistel cipher analysis," or key recovery from plaintext-ciphertext pairs.
Classical cipher analysis playbook. Use when encountering substitution ciphers, Vigenere, transposition, XOR, or encoded text in CTF challenges that requires frequency analysis, Kasiski examination, or known-plaintext cryptanalysis.
Lattice-based cryptanalysis playbook. Use when attacking RSA via Coppersmith small roots, recovering DSA/ECDSA nonces from bias, solving knapsack problems, or applying LLL/BKZ reduction to cryptographic constructions.
RSA attack playbook for CTF and real-world cryptanalysis. Use when given RSA parameters (n, e, c) and need to recover plaintext by exploiting weak keys, small exponents, shared factors, or padding oracles.
Analyzes encryption algorithms, key management, and file encryption routines used by ransomware families to assess decryption feasibility, identify implementation weaknesses, and support recovery efforts. Covers AES, RSA, ChaCha20, and hybrid encryption schemes. Activates for requests involving ransomware cryptanalysis, encryption analysis, key recovery assessment, or ransomware decryption feasibility.
Symmetric cipher attack playbook. Use when exploiting block cipher mode weaknesses (CBC padding oracle, ECB cut-and-paste, bit flipping), stream cipher key reuse, or meet-in-the-middle attacks.
Hash attack playbook. Use when exploiting length extension, MD5/SHA1 collisions, HMAC timing leaks, birthday attacks, or hash-based proof of work in CTF and authorized testing scenarios.
Systematic methodology for identifying and exploiting cryptographic implementation weaknesses in real-world applications. Covers padding oracle attacks against CBC-mode ciphers with PKCS7 padding (Vaudenay's original attack through modern padbuster automation), ECB mode exploitation including block cut-and-paste and byte-at-a-time decryption, hash length extension attacks against SHA1/SHA256/MD5-based MACs using HashPump, RSA vulnerabilities including small public exponent, common modulus, Bleichenbacher PKCS1v1.5 padding oracle, and Coppersmith's method for partial key recovery. Addresses weak PRNG exploitation targeting time-seeded generators and Mersenne Twister MT19937 state recovery from observed outputs, timing side-channel attacks against comparison operations, nonce reuse in AES-GCM leading to authentication key recovery, and key derivation weaknesses including insufficient iteration counts and missing salts. Primary tooling includes padbuster, RsaCtfTool, hashpump, and PyCryptodome for building custom exploit payloads. Maps to CWE-327 (Use of a Broken or Risky Cryptographic Algorithm), CWE-328 (Use of Weak Hash), and CWE-330 (Use of Insufficiently Random Values). Emphasizes black-box identification of vulnerable implementations before transitioning to targeted exploitation.