cairo-auditor

name	cairo-auditor
description	Audit Cairo and Starknet code for hint validation failures, felt252 overflow, builtin misuse, and Sierra-to-CASM soundness gaps. Use when reviewing Cairo contracts, prover hints, or Starknet-specific proof construction.
allowed-tools	["Read","Grep","Glob","Bash"]

cairo-auditor

Domain auditor for Cairo language and Starknet proof systems.

When to Use

• Auditing Cairo 1.0+ contracts or libraries
• Reviewing hint functions and their constraint enforcement
• Checking felt252 arithmetic for silent wrapping
• Reviewing Sierra-to-CASM compilation correctness
• Checking builtin usage (range_check, pedersen, poseidon, ec_op)

When NOT to Use

• Building initial protocol context for a new codebase — use crypto-audit-context
• Reviewing generic ZK circuit constraints outside Cairo — use zk-circuit-auditor
• Declaring a suspected Cairo bug confirmed without verification

Core Review Areas

1. Hint validation — prover hints trusted without constraint enforcement
2. felt252 overflow — arithmetic wrapping past the Stark prime silently
3. Builtin misuse — range_check, pedersen, ec_op used incorrectly
4. Sierra-to-CASM soundness — compiler guarantees relied upon but not checked
5. Storage layout — collision between storage variables, mapping key domains

Workflow

Phase 1: Hint and constraint intake

• Read references/cairo-checklist.md
• Execute workflows/hint-review.md
• Treat every hint output as hostile until constrained

Phase 2: Arithmetic and builtin review

• Check felt252 operations for silent overflow/wrapping
• Verify range_check usage covers all untrusted values
• Verify builtin arity and output validation

Phase 3: Pattern hunt

• Read references/finding-patterns.md
• Prioritize unvalidated hints, missing range checks, storage collisions

Phase 4: Handoff

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

Output Contract

Produce a Cairo-specific handoff that includes:

• The hint functions, felt252 operations, or builtins involved
• The exact validation or constraint gap under review
• Whether the issue is hint-level, arithmetic, builtin, or compiler related
• The next verification or reporting route

Reference Index

• references/cairo-checklist.md
• references/finding-patterns.md
• workflows/hint-review.md