Professional Cryptanalysis & Security Research

“Real cryptanalysis is about proof, not theft.” Learn how professional researchers evaluate ciphers, design experiments, and responsibly disclose weaknesses.

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I. 🎓 Professional Scope & Ethics

• Goal: discover mathematical or implementation weaknesses → report → help patch.

• Boundaries: only analyze data or systems you own, or that explicitly allow testing (CTFs, bug-bounty labs).

• Output: white-paper, PoC in sandbox, responsible disclosure to vendor or CVE.

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II. 🧮 Mathematical Foundation

Area	Used for	Study Toolchain
Number Theory	RSA, ECC	SageMath, PARI/GP
Finite Fields	AES mix columns, GF(2⁸)	NumPy, Sage
Modular Arithmetic	RSA, DH	Python pow(a,b,m)
Lattices	Low-exponent RSA, partial key attacks	fpylll
Probability & Entropy	Randomness tests	NIST STS suite

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III. 🔬 Algorithm Evaluation Workflow

1. Specification Review – read cipher specs (FIPS 197 for AES, RFCs for HMAC etc.).

2. Implementation Audit – check padding, mode, key management.

3. Test Vectors – verify known-good inputs produce expected outputs.

4. Differential Testing – mutate inputs to see avalanche effect behavior.

5. Statistical Tests – run frequency, runs, correlation tests.

6. Fault Simulation – use emulated bit-flips to study error propagation.

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IV. 🧠 Academic Attack Classes (Theory Only)

Attack Type	Applies To	Concept
Differential Cryptanalysis	Block ciphers	Analyze input/output differences through S-boxes
Linear Cryptanalysis	Block ciphers	Approximate cipher as linear equations
Algebraic Attack	Stream / block ciphers	Model as polynomial system solving
Timing / Power Analysis	Hardware crypto	Measure execution time or power use
Lattice / Coppersmith	RSA	Solve partial information problems mod n
Meet-in-the-Middle	Double encryption (3DES)	Trade time for memory
Boomerang / Integral	AES-like	Advanced differential variants
Fault Injection	Smart cards / chips	Induce computation errors

Each is studied in controlled academic labs with toy key sizes and public datasets.

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V. 🧩 Lab-Safe Tools for Cryptanalysis

Category	Examples	Use
Mathematical Engines	SageMath, PARI/GP, Sympy	modular math experiments
Cipher Frameworks	CrypTool 2, Crypto++	visual attack simulations
Statistical Suites	NIST STS, Dieharder	randomness tests
Side-Channel Simulators	ChipWhisperer Lite (lab edition)	trace capture & analysis
Code Auditors	Ghidra, BinaryNinja, IDA Free	reverse crypto implementations

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VI. 🧠 How to Research Ciphers Professionally

1. Build Toy Models – reduce rounds (2-4 of AES).

2. Automate Differential Search – script input pairs → collect output bias.

3. Prove Bias – use χ² tests or correlation coefficients.

4. Document Findings – graphs, equations, probabilities.

5. Responsible Disclosure – contact maintainers or publish through IACR ePrint if novel.

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VII. 📈 Entropy & Randomness Analysis

• Uniform distribution test → frequency of bits.

• Runs test → number of bit switches.

• Spectral test → periodicity. Use dieharder -a -f cipher.bin for lab experiments.

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VIII. 🔏 Key-Management and Implementation Pitfalls

• Predictable RNG (seed = time) → deterministic keys.

• Static IV or nonce reuse.

• Improper padding (PKCS#7 without check).

• Partial hash comparison (strncmp(digest, input, 8) ). Professionals model these in testbeds to teach secure coding.

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IX. 🧩 Real-World Case Studies (Summarized)

Incident	Lesson
ROCA vulnerability (Infineon RSA)	Biased prime generation → factorization possible
TLS POODLE & BEAST	CBC padding / IV reuse flaws
WEP crack	RC4 key-reuse bias
SHA-1 collision (2017)	Practical chosen-prefix collision
Debian OpenSSL bug (2008)	Predictable RNG → weak keys

These are historic research milestones — great case studies for CTF design.

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X. 🧠 Publishing & Career Path

• Submit findings to IACR ePrint, BlackHat Arsenal, or DEF CON Crypto Village.

• Study crypto engineering standards (NIST, ISO/IEC 18033).

• Engage in open research projects like PQCrypto, OpenSSL FIPS, libhydrogen.

• Document reproducible lab setups so others can verify results.

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XI. ⚙️ Safe Practice Checklist

✅ Work only on public data or your own labs ✅ Never distribute real private keys or plaintexts ✅ Respect export-control and privacy laws ✅ Cite sources and co-authors ✅ Focus on improving security, not defeating it

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XII. 📘 Suggested Reading

• Menezes et al., Handbook of Applied Cryptography

• Ferguson & Schneier, Practical Cryptography

• Katz & Lindell, Introduction to Modern Cryptography

• NIST SP 800-38 series (modes of operation)

• IACR ePrint archive for recent papers

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