# Requirements Document
## Introduction
This document specifies the requirements for comprehensive testing of the file integrity checking capabilities in the OSCAL MCP Server. The server currently implements a `verify_package_integrity` function that validates bundled OSCAL schemas and documentation files haven't been tampered with using SHA-256 hashes, but this critical security feature lacks proper test coverage.
## Glossary
- **File_Integrity_Checker**: The `verify_package_integrity` function that validates file authenticity using SHA-256 hashes
- **Hash_Manifest**: The `hashes.json` file containing expected SHA-256 hashes for all files in a package directory
- **Package_Directory**: A directory containing OSCAL files (schemas or documentation) with an associated hash manifest
- **SHA256_Hash**: Cryptographic hash function used to verify file integrity
- **Tampered_File**: A file that has been modified from its original state, resulting in a different hash
- **Missing_File**: A file listed in the hash manifest but not present in the package directory
- **Orphaned_File**: A file present in the package directory but not listed in the hash manifest
## Requirements
### Requirement 1: Hash Manifest Validation
**User Story:** As a system administrator, I want the server to validate that hash manifests are properly formatted and contain all required information, so that I can trust the file integrity checking will function correctly.
#### Acceptance Criteria
1. WHEN a hash manifest file exists, THE File_Integrity_Checker SHALL parse it as valid JSON
2. WHEN the hash manifest contains file_hashes section, THE File_Integrity_Checker SHALL validate each entry has a filename and corresponding SHA-256 hash
3. WHEN the hash manifest is malformed JSON, THE File_Integrity_Checker SHALL raise a RuntimeError with descriptive information
4. WHEN the hash manifest is missing the file_hashes section, THE File_Integrity_Checker SHALL raise a RuntimeError
5. WHEN hash values are not valid SHA-256 format, THE File_Integrity_Checker SHALL raise a RuntimeError
### Requirement 2: File Existence Verification
**User Story:** As a security engineer, I want the server to verify that all files listed in the hash manifest actually exist, so that I can detect if critical OSCAL files have been removed by an attacker.
#### Acceptance Criteria
1. WHEN verifying package integrity, THE File_Integrity_Checker SHALL check that every file listed in the hash manifest exists in the package directory
2. WHEN a file listed in the hash manifest is missing, THE File_Integrity_Checker SHALL raise a RuntimeError identifying the missing file
3. WHEN all files listed in the hash manifest exist, THE File_Integrity_Checker SHALL proceed to hash verification
4. WHEN checking file existence, THE File_Integrity_Checker SHALL use the exact filename from the hash manifest
5. WHEN the package directory itself doesn't exist, THE File_Integrity_Checker SHALL raise a RuntimeError
### Requirement 3: File Hash Verification
**User Story:** As a compliance officer, I want the server to verify that OSCAL file contents match their expected hashes, so that I can ensure the integrity of security control definitions and prevent use of tampered compliance data.
#### Acceptance Criteria
1. WHEN verifying file integrity, THE File_Integrity_Checker SHALL compute SHA-256 hash for each file in the package directory
2. WHEN a file's computed hash matches the expected hash from the manifest, THE File_Integrity_Checker SHALL continue verification
3. WHEN a file's computed hash differs from the expected hash, THE File_Integrity_Checker SHALL raise a RuntimeError identifying the tampered file and showing both hashes
4. WHEN computing hashes, THE File_Integrity_Checker SHALL read files in binary mode to ensure accurate hash calculation
5. WHEN all file hashes match their expected values, THE File_Integrity_Checker SHALL complete successfully without raising exceptions
### Requirement 4: Orphaned File Detection
**User Story:** As a security engineer, I want the server to detect files that exist in the package directory but aren't listed in the hash manifest, so that I can identify potentially malicious files that may have been added to compromise the system.
#### Acceptance Criteria
1. WHEN verifying package integrity, THE File_Integrity_Checker SHALL identify all files in the package directory
2. WHEN a file exists in the package directory but is not listed in the hash manifest, THE File_Integrity_Checker SHALL raise a RuntimeError identifying the orphaned file
3. WHEN checking for orphaned files, THE File_Integrity_Checker SHALL exclude the hash manifest file itself from validation
4. WHEN checking for orphaned files, THE File_Integrity_Checker SHALL only consider regular files, not directories or special files
5. WHEN no orphaned files are found, THE File_Integrity_Checker SHALL proceed with normal verification
### Requirement 5: Error Handling and Logging
**User Story:** As a system administrator, I want comprehensive error handling and logging for file integrity checks, so that I can troubleshoot integrity failures and monitor security events in my OSCAL deployment.
#### Acceptance Criteria
1. WHEN file integrity verification starts, THE File_Integrity_Checker SHALL log the package directory being verified
2. WHEN file integrity verification succeeds, THE File_Integrity_Checker SHALL log successful completion with file count
3. WHEN file integrity verification fails, THE File_Integrity_Checker SHALL log detailed error information before raising exceptions
4. WHEN debug logging is enabled, THE File_Integrity_Checker SHALL log individual file hash verification results
5. WHEN I/O errors occur during file reading, THE File_Integrity_Checker SHALL handle them gracefully and provide descriptive error messages
6. WHEN permission errors prevent file access, THE File_Integrity_Checker SHALL raise a RuntimeError with clear permission error details
### Requirement 6: Integration with Server Startup
**User Story:** As a DevOps engineer, I want file integrity checks to be performed during server startup, so that the OSCAL MCP server refuses to start if bundled files have been compromised, preventing the use of potentially malicious compliance data.
#### Acceptance Criteria
1. WHEN the MCP server starts, THE File_Integrity_Checker SHALL verify integrity of the oscal_schemas directory
2. WHEN the MCP server starts, THE File_Integrity_Checker SHALL verify integrity of the oscal_docs directory
3. WHEN file integrity verification fails during startup, THE MCP server SHALL exit with status code 2
4. WHEN file integrity verification succeeds during startup, THE MCP server SHALL continue normal initialization
5. WHEN integrity verification fails, THE MCP server SHALL log the failure before exiting
6. WHEN both package directories pass integrity checks, THE MCP server SHALL proceed to start the MCP protocol handler
### Requirement 7: Test Data Management
**User Story:** As a test developer, I want utilities to create and manage test data for file integrity testing, so that I can create comprehensive test scenarios including valid and invalid cases to ensure the security feature works correctly.
#### Acceptance Criteria
1. WHEN creating test scenarios, THE test utilities SHALL provide functions to create temporary package directories with hash manifests
2. WHEN testing tampered files, THE test utilities SHALL provide functions to modify file contents while preserving the original hash manifest
3. WHEN testing missing files, THE test utilities SHALL provide functions to remove files while keeping them in the hash manifest
4. WHEN testing orphaned files, THE test utilities SHALL provide functions to add files without updating the hash manifest
5. WHEN testing malformed manifests, THE test utilities SHALL provide functions to create invalid JSON or missing sections
6. WHEN cleaning up after tests, THE test utilities SHALL provide functions to safely remove temporary test directories
