Side Channel Auditor

side-channel-auditor

Domain auditor for constant-time assumptions and microarchitectural leakage risk.

When to Use

• Reviewing secret-dependent control-flow and memory-access behavior
• Auditing cache, branch-predictor, and power-related leakage surfaces
• Checking compiler/feature-flag combinations for constant-time regressions
• Verifying zeroization and error-handling latency do not leak secrets

When NOT to Use

• Protocol-level correctness audits without side-channel threat surfaces
• Purely functional bugs unrelated to timing/cache/power leakage
• Active fault-injection attacks where the attacker glitches/corrupts the computation (RSA-CRT Bellcore, DFA, verification-skip) -> fault-injection-auditor; this skill covers PASSIVE leakage only
• Declaring side-channel concerns confirmed without evidence-backed verification

Core Review Areas

1. Secret-dependent branches and control-flow decisions
2. Table lookups and cache-line dependent access patterns
3. Variable-time arithmetic and modular-reduction hotspots
4. Compiler/feature-flag regressions that reintroduce leakage
5. Operational side effects (logging, errors, zeroization) that leak validity

Workflow

Phase 1: Secret-bearing inventory

• Read references/side-channel-checklist.md
• Execute workflows/constant-time-review.md
• Enumerate secret-bearing values and trace their influence on control/data flow

Phase 2: Constant-time path analysis

• Validate constant-time helper usage and fallback behavior
• Inspect branch and memory-access patterns under secret variation
• Review compiler settings and feature flags for regression risk

Phase 3: Pattern hunt

• Read references/finding-patterns.md
• If the codebase includes a ZK prover, read references/zk-prover-patterns.md before completing the pattern hunt
• Prioritize secret-branch, table-index, optimization, and error-latency findings

Phase 4: Handoff

• Send surviving findings to crypto-fp-check
• Use zkbugs-index only after the finding survives verification

Output Contract

Produce a side-channel-specific handoff that includes:

• The secret-bearing value and affected control/data path
• The leakage class (timing, cache, memory, power, or operational)
• Tool-backed evidence status (dudect, ctgrind, microbenchmarks) if available
• The next verification or reporting route

Reference Index

• references/side-channel-checklist.md
• references/finding-patterns.md
• references/zk-prover-patterns.md
• workflows/constant-time-review.md