crypto-analysis
Use when assessing cryptography — TLS/PKI auditing, RSA/ECC key attacks, ECDSA nonce lattice recovery, symmetric/AEAD misuse, JWT/JOSE forgery, hash cracking, post-quantum migration review
Install / Use
npx skills add hypnguyen1209/offensive-claude --skill crypto-analysisInstalls into whichever agent you are using.
SKILL.md
Installable skill definition
Quality Score
Category
SecuritySupported Platforms
Our assessment of crypto-analysis
crypto-analysis scores 86/100 on our quality scale, 718th of 1,096 Security skills we index.
Its SKILL.md is 8.5 KB long, well organised into 14 sections with 1 code example: a thorough specification that gives an agent plenty to work with.
It has 377 GitHub stars, a meaningful sign that others use it.
Maintenance, license and trust
- The repository was last updated 14 days ago, so crypto-analysis is actively maintained.
- It is released under the MIT license, a permissive license that allows use, modification and commercial use with attribution.
- Its trust signals score 100/100, with no cautions. These come from repository metadata, not a code audit — read the skill file before letting an agent act on it.
Safety scan
No issues foundOur scan of the whole file found no instruction hijacking, hidden characters, credential access, data exfiltration or destructive commands.
Automated pattern scan on 2026-10-05. It catches known dangerous patterns, not every risk — read a skill before letting an agent act on it.
crypto-analysis compared with similar skills
All 4 of these similar skills score higher than crypto-analysis; compare them before choosing.
| Skill | Score | Stars | Updated | Format |
|---|---|---|---|---|
| crypto-analysis (this skill)by hypnguyen1209 | 86 | 377 | 14d ago | SKILL.md |
| algorithmic-artby anthropics | 100 | 177.9k | 12d ago | SKILL.md |
| pptxby anthropics | 100 | 177.9k | 12d ago | SKILL.md |
| designby nextlevelbuilder | 100 | 130.2k | 13d ago | SKILL.md |
| ui-ux-pro-maxby nextlevelbuilder | 100 | 130.2k | 13d ago | SKILL.md |
Frequently asked questions
- How do I install crypto-analysis?
- Run
npx skills add hypnguyen1209/offensive-claude --skill crypto-analysis. The install tabs above show the steps for each supported agent. - Which AI agents does crypto-analysis work with?
- It is written for Universal, as a SKILL.md file. Other agents that read the same format can often use it too.
- Is crypto-analysis safe to use?
- Our scan of the whole file found no instruction hijacking, hidden characters, credential access, data exfiltration or destructive commands. It is MIT-licensed and scores 100/100 on trust signals. Skills are instructions an agent will follow, so read the file before installing it and do not approve commands you do not understand.
- Is crypto-analysis still maintained?
- The repository was last updated 14 days ago, so crypto-analysis is actively maintained.
Skill content
View source on GitHubname: crypto-analysis description: Use when assessing cryptography — TLS/PKI auditing, RSA/ECC key attacks, ECDSA nonce lattice recovery, symmetric/AEAD misuse, JWT/JOSE forgery, hash cracking, post-quantum migration review metadata: type: offensive phase: analysis tools: testssl.sh, openssl, hashcat, john, RsaCtfTool, sagemath, jwt_tool, ecdsa-lattice mitre: [T1600, T1600.001, T1557, T1110.002, T1552.004, T1606.001, T1040] kill_chain: phase: [recon, exploit] step: [1, 4] attck_tactics: [TA0043, TA0006, TA0009] attck_techniques: [T1600, T1600.001, T1557, T1557.001, T1110.002, T1552.004, T1606.001, T1040] depends_on: [recon-osint] feeds_into: [exploit-development, web-pentest, network-attack] inputs: [tls_config, crypto_implementation, hash_samples, public_keys, jwt_tokens, signature_corpus] outputs: [crypto_weakness_report, finding_record, recovered_keys, cracked_credentials] references:
- references/tls-pki-audit.md
- references/rsa-attacks.md
- references/ecc-nonce-attacks.md
- references/symmetric-aead.md
- references/jwt-jose.md
- references/hash-pq.md scripts:
- scripts/tls_audit.py
- scripts/rsa_attack.py
- scripts/ecdsa_lattice.py
- scripts/padding_oracle.py
- scripts/gcm_nonce_reuse.py
- scripts/jwt_forge.py
- scripts/hash_triage.py
Cryptographic Analysis
When to Activate
- Auditing TLS/SSL/SSH configurations and X.509 PKI (cipher suites, downgrade, protocol flaws)
- Reviewing crypto implementations in source code or captured traffic
- Attacking weak RSA/ECC keys (CTF and real-world weak-key hygiene)
- Recovering ECDSA/DSA private keys from reused or biased nonces (lattice/HNP)
- Exploiting symmetric/AEAD misuse: padding oracles, GCM nonce reuse, key-commitment
- Forging JWT/JOSE tokens (algorithm confusion, none, jwk/jku/kid injection)
- Cracking password hashes and grading KDF strength
- Assessing post-quantum readiness ("harvest now, decrypt later" exposure)
Technique Map
| Technique | ATT&CK | CWE | Reference | Script | |-----------|--------|-----|-----------|--------| | TLS cipher/protocol downgrade audit | T1600.001 | CWE-326 | references/tls-pki-audit.md | scripts/tls_audit.py | | Terrapin SSH prefix truncation (CVE-2023-48795) | T1557 | CWE-222 | references/tls-pki-audit.md | scripts/tls_audit.py | | Marvin/Bleichenbacher RSA timing oracle | T1600 | CWE-208 | references/tls-pki-audit.md | scripts/tls_audit.py | | X.509 / CT-log shadow-asset discovery | T1589 | CWE-295 | references/tls-pki-audit.md | scripts/tls_audit.py | | RSA weak-key factoring (Fermat/Wiener/common-modulus) | T1600 | CWE-326 | references/rsa-attacks.md | scripts/rsa_attack.py | | Coppersmith partial-key & ROCA (CVE-2017-15361) | T1600 | CWE-310 | references/rsa-attacks.md | scripts/rsa_attack.py | | Hastad broadcast / batch-GCD | T1600 | CWE-326 | references/rsa-attacks.md | scripts/rsa_attack.py | | ECDSA nonce reuse key recovery | T1552.004 | CWE-323 | references/ecc-nonce-attacks.md | scripts/ecdsa_lattice.py | | Biased-nonce lattice/HNP (Minerva, PuTTY CVE-2024-31497) | T1552.004 | CWE-1241 | references/ecc-nonce-attacks.md | scripts/ecdsa_lattice.py | | Psychic signature (0,0) (CVE-2022-21449) | T1606.001 | CWE-347 | references/ecc-nonce-attacks.md | scripts/ecdsa_lattice.py | | CBC padding oracle (byte-by-byte decrypt) | T1040 | CWE-209 | references/symmetric-aead.md | scripts/padding_oracle.py | | AES-GCM nonce reuse "forbidden attack" | T1040 | CWE-323 | references/symmetric-aead.md | scripts/gcm_nonce_reuse.py | | AEAD key-commitment / invisible salamanders / partitioning oracle | T1606 | CWE-347 | references/symmetric-aead.md | scripts/gcm_nonce_reuse.py | | JWT algorithm confusion RS256→HS256 (CVE-2024-54150) | T1606.001 | CWE-347 | references/jwt-jose.md | scripts/jwt_forge.py | | JWT alg=none / jwk / jku / kid injection | T1606.001 | CWE-347 | references/jwt-jose.md | scripts/jwt_forge.py | | Hash identification & GPU cracking | T1110.002 | CWE-916 | references/hash-pq.md | scripts/hash_triage.py | | Weak KDF / fast-hash password storage | T1110.002 | CWE-916 | references/hash-pq.md | scripts/hash_triage.py | | Post-quantum / HNDL exposure review | T1600 | CWE-327 | references/hash-pq.md | scripts/tls_audit.py |
Quick Start
# 0. TLS/PKI posture in one shot (downgrade, ROBOT, SWEET32, Terrapin, cert/CT)
python3 scripts/tls_audit.py target.com:443 --ssh target.com:22 --ct --json out.json
testssl.sh --full --robot --sweet32 https://target.com # cross-check with the canonical tool
# 1. RSA weak-key triage on a captured public key
python3 scripts/rsa_attack.py --pubkey server.pem --ct ciphertext.b64 --auto
# tries Fermat (p~=q), Wiener (small d), batch-GCD/common-modulus, ROCA fingerprint
# 2. ECDSA key recovery from a signature corpus (reuse or bias)
python3 scripts/ecdsa_lattice.py recover sigs.json --curve secp256r1 --known-msb 4
# reuse: needs 2 sigs w/ same r; bias: ~256-1200 sigs depending on leak
# 3. Symmetric/AEAD misuse
python3 scripts/padding_oracle.py --url https://t/dec --ct $CT --block 16 # CBC oracle
python3 scripts/gcm_nonce_reuse.py forbidden ct1.bin ct2.bin --nonce $N # recover H + forge
# 4. JWT forgery chain
python3 scripts/jwt_forge.py confusion --pubkey jwt_pub.pem --claims '{"role":"admin"}'
python3 scripts/jwt_forge.py none --claims '{"sub":"admin"}'
# 5. Hash triage + crack plan
python3 scripts/hash_triage.py hashes.txt # identify + emit hashcat -m / john format
hashcat -m 22000 capture.hc22000 wl.txt -r rules/best64.rule
OPSEC & Detection (summary)
| Technique | Telemetry / IOC | Detection (Sigma/EDR) | OPSEC note |
|-----------|-----------------|-----------------------|------------|
| TLS scanning / testssl | Burst of handshakes, many cipher renegotiations, malformed ClientHellos | NIDS: high TLS alert rate from one src; Zeek ssl.log anomalous cipher offers | Rate-limit, spread across source IPs; passive cert/CT recon leaves no target-side trace |
| Marvin/ROBOT oracle probing | ~10^4–10^6 RSA decrypts, repeated malformed pre-master/CMS | WAF/IDS: spike of TLS decrypt errors, identical-size payloads | Extremely loud; only against authorized hosts; use minimal query budgets |
| Terrapin MitM | Injected SSH_MSG_IGNORE, sequence-number gap at NEWKEYS | SSH server logs kex mismatch; netflow showing on-path device | Requires active MitM; detectable by strict-kex peers; abort if kex-strict present |
| ECDSA nonce harvesting | Bulk signature collection (Git, TLS, SSH, blockchain) | Mostly offline — no target telemetry once sigs captured | Collection is passive; recovery is offline; rotate-key advice in report |
| CBC padding oracle | Thousands of decrypt requests, alternating valid/invalid padding | Web logs: ~256×blocks requests to one endpoint; Sigma on 4xx burst | Very noisy (256×blocks×msgs); throttle, randomize timing |
| GCM nonce reuse / partitioning | Repeated (nonce,key) pairs; multi-key ciphertext blobs | App crypto audit; flag reused IVs in logs | Forbidden-attack math is offline once two ciphertexts captured |
| JWT forgery | Anomalous alg, external jku/x5u fetch, all-zero ES signature | Sigma: JWT with alg:none/HS after RS expected; egress to attacker JWKS URL | Each forged token is a single request; minimal noise |
| Hash cracking | None on target (offline) | N/A unless online spray (then T1110) | Offline; protect loot at rest; never spray live without scope |
Deep Dives
- references/tls-pki-audit.md — TLS/SSL/SSH posture: cipher/protocol downgrade, Terrapin (CVE-2023-48795), Marvin/Bleichenbacher (CVE-2022-4304, CVE-2024-2236), SWEET32/DROWN/Logjam/POODLE, X.509 and Certificate-Transparency analysis.
- references/rsa-attacks.md — Weak-key factoring: Fermat, Wiener, common modulus, Hastad broadcast, Coppersmith partial-key, batch-GCD, ROCA (CVE-2017-15361); RsaCtfTool / cado-nfs / SageMath workflow.
- references/ecc-nonce-attacks.md — ECDSA/DSA nonce reuse, biased-nonce lattice/HNP recovery (Minerva, PuTTY CVE-2024-31497), invalid-curve attacks, psychic signatures (CVE-2022-21449).
- references/symmetric-aead.md — Block-cipher mode misuse: ECB detection, CBC padding oracle, CTR/GCM nonce reuse (forbidden attack), AEAD key-commitment / invisible salamanders / partitioning oracles.
- references/jwt-jose.md — JWT/JOSE token forgery: algorithm confusion (CVE-2024-54150), alg=none, jwk/jku/x5u/kid injection, weak-secret cracking, library-level CVE landscape.
- references/hash-pq.md — Hash identification, modern GPU cracking economics (RTX 40/50-series), KDF strength grading, and post-quantum migration / "harvest now, decrypt later" assessment (ML-KEM/ML-DSA, hybrid TLS, crypto-agility).
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Trust signals
From repository metadata: license, adoption, age and documentation. Not a code audit — see the Safety scan above for what the skill file itself contains.
