# Crypto Vulnerability Analyst

> Analyze cryptographic design and implementation for misuse, key-management weaknesses, and protocol-level exploit opportunities.

- Skill: `netvar1337/crypto-vulnerability-analyst` (Agent Skill)
- Install (CLI): `npx skillmds@latest add netvar1337/crypto-vulnerability-analyst`
- Raw SKILL.md: https://api.skillmd.com/api/skills/netvar1337/crypto-vulnerability-analyst/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security
- Author: netvar1337 (https://skillmd.com/u/netvar1337)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/netvar1337/crypto-vulnerability-analyst

---


# Crypto Vulnerability Analyst

## Purpose
Find exploitable cryptographic weakness across primitive choice, implementation details, and protocol flow.

## Inputs
- `code_or_binary_context`
- `protocol_description`
- `key_management_model`

## Workflow
### Phase 1: Crypto Inventory
1. Identify algorithms, modes, and libraries.
2. Identify key derivation and randomness sources.
3. Identify trust anchors and certificate behavior.

### Phase 2: Misuse Detection
1. Nonce/IV reuse or predictability.
2. Weak or obsolete algorithms/modes.
3. Insecure comparisons and padding issues.
4. Missing authenticity or misuse of MAC/AEAD.

### Phase 3: Key Lifecycle Review
1. Key generation entropy quality.
2. Key storage and exposure paths.
3. Rotation, revocation, and scope boundaries.

### Phase 4: Protocol Attack Analysis
1. Replay and reflection opportunities.
2. Downgrade and negotiation weaknesses.
3. Oracle-like behavior from error distinctions.

### Phase 5: Risk and Fix Prioritization
1. Separate compliance issues from exploitable flaws.
2. Prioritize fixes by exploit practicality.
3. Provide migration-safe remediation guidance.

## Crypto Assessment Matrix
| Area | Failure Pattern |
|---|---|
| encryption | unauthenticated encryption for sensitive state |
| key management | shared static keys across tenants/environments |
| randomness | predictable nonce/session token generation |
| protocol | downgrade and replay not cryptographically bound |

## Output Contract
```json
{
  "crypto_inventory": [],
  "misuse_findings": [],
  "protocol_risks": [],
  "key_management_gaps": [],
  "prioritized_remediation": []
}
```

## Constraints
- Do not equate deprecated with exploitable without context.
- Clearly label confidence when implementation visibility is partial.

## Quality Checklist
- [ ] Primitive and mode details are explicit.
- [ ] Exploit path is technically plausible.
- [ ] Remediation is concrete.

## Detailed Operator Notes
### Validation Discipline
- Confirm static assumptions with targeted runtime checks.
- Keep one controlled input per hypothesis.
- Separate symbol-level hints from observed behavior.

### Exploitability Heuristics
- Control quality over corrupted bytes/pointers.
- Trigger repeatability across process restarts.
- Mitigation interaction required for practical exploitation.

### Common Blind Spots
- Architecture-specific undefined behavior differences.
- Parser edge cases reachable only through nested formats.
- Configuration-dependent code paths not visible in default runs.

### Reporting Rules
- Include prerequisite runtime conditions.
- Include why alternative bug classes were rejected.
- Include a minimal regression-test suggestion for remediation.

## Quick Scenarios
### Scenario A: Control Validation
- Trigger candidate primitive with minimal input.
- Confirm memory/register side effect.
- Repeat across restarts for stability.
- Record constraints that break control.

### Scenario B: Mitigation Interaction
- Confirm active hardening controls.
- Test whether primitive survives mitigations.
- Distinguish crash-only from exploit-capable outcomes.
- Capture bypass requirements if needed.

### Scenario C: Reporting Readiness
- Verify prerequisite environment notes.
- Verify reproduction steps are deterministic.
- Verify impact statement is evidence-bound.
- Verify remediation target is specific.

## Conditional Decision Matrix
| Condition | Action | Evidence Requirement |
|---|---|---|
| Crash reproduces inconsistently | reduce input and isolate triggering fields | minimal trigger artifact |
| Primitive appears but control unclear | instrument memory/register checkpoints | control-surface trace |
| Mitigation blocks direct exploitation | model required bypass preconditions | mitigation interaction notes |
| Parser path uncertain | force parser branch with crafted corpus | branch-selection evidence |
| Static finding lacks runtime proof | add targeted runtime probe before reporting | runtime validation artifact |

## Advanced Coverage Extensions
1. Compare behavior across compiler optimization levels when possible.
2. Check locale/encoding effects on parser and boundary logic.
3. Check integer truncation across 32/64-bit interfaces.
4. Check allocator behavior differences under memory pressure.
5. Check cryptographic error oracles via differential response paths.