# Binary Reachability Analysis

## Module
BinaryIndex

## Status
IMPLEMENTED

## Description
Binary-level reachability analysis integrating with the ReachGraph and taint gate extraction for function-level exploitability assessment.

## Implementation Details
- **Modules**: `src/BinaryIndex/__Libraries/StellaOps.BinaryIndex.Analysis/`
- **Key Classes**:
  - `ReachGraphBinaryReachabilityService` (`src/BinaryIndex/__Libraries/StellaOps.BinaryIndex.Analysis/ReachGraphBinaryReachabilityService.cs`) - connects binary analysis to the ReachGraph module for function-level reachability
  - `TaintGateExtractor` (`src/BinaryIndex/__Libraries/StellaOps.BinaryIndex.Analysis/TaintGateExtractor.cs`) - identifies taint gate types (BoundsCheck, NullCheck, AuthCheck, PermissionCheck, TypeCheck) from condition strings
  - `SignatureMatcher` (`src/BinaryIndex/__Libraries/StellaOps.BinaryIndex.Analysis/SignatureMatcher.cs`) - matches vulnerability signatures at the binary level
- **Models**: `AnalysisResultModels`, `FingerprintModels`, `SignatureIndexModels` (`src/BinaryIndex/__Libraries/StellaOps.BinaryIndex.Analysis/Models/`)
- **Interfaces**: defined in `Interfaces.cs`, implementations in `Implementations.cs`

## E2E Test Plan
- [ ] Submit a binary with a known vulnerable function and verify reachability analysis identifies it as reachable from entry points
- [ ] Verify `TaintGateExtractor` correctly classifies all gate types (bounds, null, auth, permission, type checks)
- [ ] Verify that unreachable vulnerable functions reduce the exploitability score
- [ ] Verify integration between `ReachGraphBinaryReachabilityService` and the ReachGraph module
- [ ] Verify that taint gate presence between entry point and vulnerable function is reflected in the analysis result