Cryptographic Analysis & Assessment

# Cryptographic Analysis & Assessment

## Purpose

Enable Claude to assist with cryptographic security assessments including SSL/TLS configuration auditing, cipher suite analysis and recommendation, hash algorithm identification, encryption implementation code review, key management evaluation, and detection of cryptographic vulnerabilities. Claude directly analyzes provided configurations and code.

---

## Activation Triggers

This skill activates when the user asks about:
- Auditing SSL/TLS configuration of a server or service
- Evaluating cipher suites for security strength
- Identifying hash algorithms from hash values or code
- Reviewing code for cryptographic implementation flaws
- Assessing key lengths, key management, or rotation policies
- Detecting hardcoded keys, weak IVs, or ECB mode usage
- Generating TLS configuration recommendations (Mozilla profile)
- Certificate analysis (expiration, chain, transparency)
- Post-quantum cryptography guidance
- Password hashing implementation review (bcrypt, Argon2, PBKDF2)

---

## Prerequisites

```bash
pip install cryptography requests pyOpenSSL
```

**Recommended tools:**
- `sslyze` — Python TLS scanner
- `testssl.sh` — Comprehensive TLS testing
- `openssl` — Command-line TLS operations
- `Wireshark` — TLS traffic analysis
- `certbot` — Certificate management

---

## Core Capabilities

### 1. SSL/TLS Configuration Auditing

**When the user asks to audit TLS for a server or paste a TLS configuration:**

**Command-line audit approach:**
```bash
# Quick TLS check using openssl
openssl s_client -connect example.com:443 -tls1_2 2>/dev/null | grep -E "Protocol|Cipher"
openssl s_client -connect example.com:443 -tls1 2>/dev/null | grep -E "handshake|error"

# Check certificate details
openssl s_client -connect example.com:443 </dev/null 2>/dev/null | openssl x509 -noout -dates -subject -issuer

# Comprehensive scan with sslyze
sslyze --regular example.com --json_out result.json

# Or testssl.sh (most comprehensive)
./testssl.sh --severity HIGH --quiet example.com

# Use the skill's script
python scripts/tls_auditor.py --host example.com --port 443 --output report.json
python scripts/tls_auditor.py --host mail.example.com --port 993 --grade
```

**TLS Version Support Ratings:**
| Protocol | Status | Action |
|----------|--------|--------|
| SSLv2 | Critically broken | Block immediately |
| SSLv3 | Broken (POODLE) | Block immediately |
| TLS 1.0 | Deprecated (PCI-DSS violation) | Disable — BEAST, POODLE |
| TLS 1.1 | Deprecated | Disable |
| TLS 1.2 | Acceptable (with strong ciphers) | Keep with restrictions |
| TLS 1.3 | Current standard | Enable and prefer |

**TLS Vulnerability Checklist:**
```
[ ] Heartbleed (CVE-2014-0160): openssl s_client + heartbleed test
[ ] POODLE: SSLv3 enabled?
[ ] BEAST: TLS 1.0 + CBC cipher?
[ ] ROBOT: RSA key exchange supported?
[ ] DROWN: SSLv2 on any port of same server?
[ ] Logjam/FREAK: DHE < 2048-bit or EXPORT ciphers?
[ ] CRIME/BREACH: TLS compression enabled?
[ ] Sweet32: 3DES (64-bit block cipher) supported?
[ ] Weak certificate: RSA < 2048-bit, SHA-1 signed?
[ ] Certificate validity: Not expired, chain complete, not self-signed for prod?
[ ] HSTS: Strict-Transport-Security header present?
[ ] CT: Certificate in public transparency logs?
```

### 2. Cipher Suite Strength Evaluation

**When the user asks about cipher suite security:**

**TLS 1.3 Cipher Suites (All Secure — Use These):**
| Cipher Suite | Key Exchange | Auth | Encryption | MAC | Rating |
|-------------|-------------|------|------------|-----|--------|
| TLS_AES_256_GCM_SHA384 | ECDHE | RSA/ECDSA | AES-256-GCM | SHA-384 | A+ |
| TLS_CHACHA20_POLY1305_SHA256 | ECDHE | RSA/ECDSA | ChaCha20 | Poly1305 | A+ |
| TLS_AES_128_GCM_SHA256 | ECDHE | RSA/ECDSA | AES-128-GCM | SHA-256 | A |

**TLS 1.2 Cipher Suite Ratings:**
| Cipher Suite | Rating | Notes |
|-------------|--------|-------|
| ECDHE-ECDSA-AES256-GCM-SHA384 | A+ | Perfect — AEAD, PFS |
| ECDHE-RSA-AES256-GCM-SHA384 | A+ | Perfect — AEAD, PFS |
| ECDHE-RSA-AES128-GCM-SHA256 | A | Good — AEAD, PFS |
| DHE-RSA-AES256-GCM-SHA384 | A | Good — if DHE ≥ 2048-bit |
| AES256-GCM-SHA384 | B | No forward secrecy |
| ECDHE-RSA-AES256-SHA384 | B | CBC mode (timing attacks) |
| RC4-SHA | F | RC4 broken — never use |
| DES-CBC3-SHA | F | 3DES vulnerable (Sweet32) |
| NULL-SHA | F | No encryption |
| EXPORT-RC4-MD5 | F | FREAK vulnerable |

**Recommended nginx TLS Configuration (Mozilla Modern Profile):**
```nginx
ssl_protocols TLSv1.2 TLSv1.3;
ssl_prefer_server_ciphers off;  # TLS 1.3 ignores this; client order for TLS 1.2

# For TLS 1.2 compatibility
ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384;

# DH parameters for DHE cipher suites
ssl_dhparam /etc/nginx/dhparam.pem;  # Generate: openssl dhparam -out dhparam.pem 4096

# Session management
ssl_session_timeout 1d;
ssl_session_cache shared:SSL:10m;
ssl_session_tickets off;  # Disabling improves forward secrecy

# HSTS
add_header Strict-Transport-Security "max-age=63072000; includeSubDomains; preload" always;

# OCSP Stapling
ssl_stapling on;
ssl_stapling_verify on;
resolver 1.1.1.1 8.8.8.8 valid=300s;
```

**Generate DH parameters:**
```bash
# 4096-bit DH parameters (do this once, takes a few minutes)
openssl dhparam -out /etc/nginx/dhparam.pem 4096
```

### 3. Hash Algorithm Identification & Assessment

**When the user provides a hash value or asks to identify hash algorithms:**

**Hash Identification by Format:**
| Hash Format / Length | Algorithm | Security Status |
|----------------------|-----------|----------------|
| 32 hex chars | MD5 | Broken — collision attacks exist |
| 40 hex chars | SHA-1 | Deprecated — SHAttered collision |
| 56 hex chars | SHA-224 | Acceptable (limited use) |
| 64 hex chars | SHA-256 | Current standard |
| 96 hex chars | SHA-384 |