--- name: cryptographic-audit-c492aaaab80d description: Audit cryptographic implementations for misuse, weak algorithms, improper key management, and TLS/certificate configuration issues. Uses testssl.sh, openssl, sslyze, and code review patterns. For authorized security assessments. --- # Cryptographic Audit ## When to Use Use when reviewing cryptographic implementations, auditing TLS configurations, assessing key management practices, or checking for common crypto anti-patterns in source code. ## Tool Reference | Tool | Package | Purpose | |------|---------|---------| | `testssl.sh` | testssl.sh | TLS/SSL configuration scanner | | `openssl` | openssl | Certificate/cipher inspection | | `sslyze` | pip:sslyze | Python TLS scanner | | `certtool` | gnutls | Certificate manipulation | | `step` | smallstep/cli | CA and certificate toolkit | | `age` | age | Modern file encryption | | `minisign` | minisign | Signature verification | | `hashid` | pip:hashid | Hash type identification | | `john` | john | Password hash auditing | | `hashcat` | hashcat | GPU hash cracking | | `xortool` | pip:xortool | XOR cipher analysis | | `featherduster` | featherduster | Automated crypto analysis | ## TLS Configuration Audit ### 1. Quick Scan ```bash # Comprehensive TLS test testssl.sh --severity HIGH https://target.com # Check specific issues testssl.sh --heartbleed --ccs --robot --breach https://target.com # JSON output for processing testssl.sh --jsonfile results.json https://target.com ``` ### 2. Certificate Chain ```bash # Download and inspect certificate chain openssl s_client -connect target.com:443 -showcerts /dev/null | \ openssl x509 -text -noout # Check certificate expiry echo | openssl s_client -connect target.com:443 2>/dev/null | \ openssl x509 -noout -dates # Verify certificate chain openssl s_client -connect target.com:443 -verify 5 /dev/null | \ openssl x509 -noout -ext ct_precert_scts # SAN (Subject Alternative Names) echo | openssl s_client -connect target.com:443 2>/dev/null | \ openssl x509 -noout -ext subjectAltName ``` ### 3. Cipher Suite Analysis ```bash # List supported ciphers nmap --script ssl-enum-ciphers -p 443 target.com # Test specific cipher openssl s_client -connect target.com:443 -cipher 'RC4-SHA' # Check for weak ciphers sslyze --regular target.com:443 # TLS 1.3 cipher suites openssl s_client -connect target.com:443 -tls1_3 -ciphersuites 'TLS_AES_256_GCM_SHA384' ``` ### 4. Protocol Version Testing ```bash # Test each protocol version for proto in ssl3 tls1 tls1_1 tls1_2 tls1_3; do echo -n "$proto: " openssl s_client -connect target.com:443 -$proto &1 | \ grep -q "Cipher is" && echo "SUPPORTED" || echo "not supported" done ``` ### 5. HSTS and Security Headers ```bash # Check HSTS header curl -sI https://target.com | grep -i strict-transport # Full security headers check curl -sI https://target.com | grep -iE \ 'strict-transport|content-security|x-frame|x-content-type|referrer-policy' ``` ## Key Management Audit ### 1. Private Key Assessment ```bash # Check key strength openssl rsa -in key.pem -text -noout | head -1 # Look for: RSA < 2048 bits = WEAK # Check EC curve openssl ec -in ec_key.pem -text -noout | grep ASN1 # Look for: < P-256 = WEAK, P-192 = CRITICAL # Detect if key is encrypted openssl rsa -in key.pem -check -noout 2>&1 # "unable to load" = encrypted (good) # No error = unencrypted (finding) ``` ### 2. Entropy Assessment ```bash # Check /dev/urandom availability ls -la /dev/urandom /dev/random # Test PRNG output quality (basic) dd if=/dev/urandom bs=1M count=10 2>/dev/null | ent # Check OpenSSL PRNG seeding openssl rand -hex 32 # Should succeed without errors ``` ## Password Hashing Audit ```bash # Identify hash type hashid '$2b$12$LJ3...' # => bcrypt # Check hash strength # WEAK: MD5, SHA1, SHA256 (unsalted/fast) # OK: bcrypt ($2b$), scrypt, argon2 # BEST: argon2id with ≥64MB memory # Benchmark cracking speed (measure weakness) hashcat -b -m 0 # MD5: billions/sec = WEAK hashcat -b -m 3200 # bcrypt: thousands/sec = OK hashcat -b -m 13100 # argon2: tens/sec = STRONG ``` ## Code Review Patterns ### Hardcoded Secrets ```python # FINDING: Hardcoded cryptographic key AES_KEY = b"0123456789abcdef" # Static key in source SECRET = "my-jwt-secret" # Hardcoded JWT signing key # GREP: Find hardcoded secrets # grep -rn 'SECRET\|KEY\|PASSWORD\|TOKEN.*=.*["\x27]' --include='*.py' ``` ### Weak Random Number Generation ```python # FINDING: Using non-cryptographic PRNG for security import random token = random.randint(0, 999999) # Predictable! session_id = ''.join(random.choices(string.ascii_letters, k=32)) # FIX: Use secrets module import secrets token = secrets.token_hex(32) ``` ### ECB Mode Usage ```python # FINDING: ECB mode leaks patterns cipher = AES.new(key, AES.MODE_ECB) # NEVER use ECB # FIX: Use GCM (authenticated encryption) cipher = AES.new(key, AES.MODE_GCM, nonce=nonce) ``` ### Nonce Reuse ```python # FINDING: Static or reused nonce/IV iv = b'\x00' * 16 # Static IV = catastrophic for CTR/GCM cipher = AES.new(key, AES.MODE_GCM, nonce=iv) # FIX: Generate fresh nonce per encryption nonce = os.urandom(12) ``` ### Padding Oracle Exposure ```python # FINDING: Error message reveals padding validity try: plaintext = cipher.decrypt(ciphertext) unpad(plaintext) except PaddingError: return "Invalid padding" # Oracle! except: return "Decryption failed" # FIX: Use authenticated encryption (GCM/ChaCha20-Poly1305) # or return identical error for all failures ``` ### Insecure Hash for Integrity ```python # FINDING: MD5/SHA1 for integrity verification checksum = hashlib.md5(data).hexdigest() # Collision attacks practical # FIX: Use SHA-256+ or HMAC mac = hmac.new(key, data, hashlib.sha256).hexdigest() ``` ### Missing Certificate Pinning ```python # FINDING: No certificate pinning in mobile/API client requests.get("https://api.example.com", verify=True) # Trusts any valid CA # Pin to specific certificate or public key hash # Use: ssl.SSLContext with load_verify_locations() + custom check ``` ### JWT Vulnerabilities ```python # FINDING: JWT algorithm confusion token = jwt.decode(token_string, key, algorithms=["HS256", "RS256", "none"]) # "none" algorithm = signature bypass # HS256+RS256 = algorithm confusion attack # FIX: Whitelist single algorithm token = jwt.decode(token_string, key, algorithms=["RS256"]) ``` ## Grep Patterns for Crypto Issues ```bash # Find weak algorithms grep -rn 'MD5\|SHA1\|DES\|RC4\|ECB' --include='*.py' --include='*.js' --include='*.go' --include='*.java' # Find hardcoded keys/secrets grep -rn 'SECRET_KEY\|API_KEY\|PRIVATE.*=.*["'"'"']' --include='*.py' --include='*.env' # Find insecure random grep -rn 'Math\.random\|random\.randint\|rand()' --include='*.py' --include='*.js' --include='*.go' # Find disabled TLS verification grep -rn 'verify.*=.*False\|InsecureSkipVerify.*true\|NODE_TLS_REJECT_UNAUTHORIZED' . # Find nonce/IV issues grep -rn 'iv.*=.*b"\|nonce.*=.*b"\|IV.*=.*new byte' --include='*.py' --include='*.java' ``` ## Output Format ```markdown ## Cryptographic Audit Report ### TLS Configuration | Check | Status | Details | |-------|--------|---------| | Protocol versions | WARN | TLS 1.0/1.1 enabled | | Cipher suites | FAIL | RC4, 3DES accepted | | Certificate | PASS | RSA-2048, valid chain | | HSTS | FAIL | Header missing | | Forward secrecy | PASS | ECDHE supported | ### Cryptographic Implementation Findings | # | Finding | Severity | File:Line | |---|---------|----------|-----------| | 1 | Hardcoded AES key | Critical | config.py:42 | | 2 | ECB mode encryption | High | crypto.py:18 | | 3 | MD5 for password hashing | High | auth.py:55 | | 4 | Math.random() for tokens | High | session.js:12 | | 5 | JWT "none" algorithm accepted | Critical | api.py:89 | ### Recommendations 1. Rotate all hardcoded keys to secrets manager 2. Replace ECB with AES-256-GCM 3. Migrate passwords to argon2id 4. Use crypto.getRandomValues() / secrets module 5. Pin JWT algorithm to RS256 only ``` ## 2600 Heritage Cryptography has been central to 2600 since the magazine's earliest issues. From covering PGP and the Clipper Chip in the 1990s crypto wars, to the DeCSS case (the landmark DMCA lawsuit against 2600 for publishing DVD decryption code), to modern TLS and end-to-end encryption advocacy — the magazine has consistently championed strong cryptography as a civil liberty. --- Source attribution: plurigrid Original project: https://github.com/plurigrid/asi/blob/293ce9f76e3abcd5ba18db284688bc0d9ac6691d/skills/cryptographic-audit/SKILL.md License: MIT License information: https://opensource.org/license/mit Original upstream instructions; downloaded from Mega AI Hub. ## Upstream license notice MIT License Copyright (c) 2025 SkillCreator.ai Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. # Mega AI Hub resource metadata Creator / publisher: plurigrid Original project: https://github.com/plurigrid/asi/blob/293ce9f76e3abcd5ba18db284688bc0d9ac6691d/skills/cryptographic-audit/SKILL.md Attribution basis: Source repository record Fields of work: Development & Engineering Roles: Backend Developer, DevOps / SRE, Security Engineer Specialties: Backend Tools: Gnutls, Hashcat, Openssl, Sslyze, Testssl.Sh Country applicability: Country not specified Classification basis: Source catalog labels Instruction SHA-256: 4b59323f23c7c9bfd2094ad393a242dbcce42832a1541d6a09ac3a7a19d4b51d