Implement Tamper-Evident Audit Logging System with BLAKE3 Cryptographic Chain

[unclesp1d3r]

Overview

This task implements a cryptographically secure audit logging system based on a Certificate Transparency-style Merkle tree that provides tamper detection and forensic integrity for the DaemonEye project. The system uses BLAKE3 hashing with rs-merkle to create an immutable audit ledger with inclusion proofs and periodic checkpoints.

Problem Statement

Current security monitoring systems often lack cryptographic guarantees for audit log integrity. Without tamper-evident logging, malicious actors who gain access to systems can modify or delete audit trails to cover their tracks, compromising incident response and forensic investigations.

Proposed Solution

Architecture Overview

The audit ledger implements a Certificate Transparency-style Merkle log backed by redb with the following key components:

• Append-only sequence of canonical JSON leaf entries
• BLAKE3 leaf hashing for uniform cryptographic integrity
• Incremental Merkle root updates with O(log n) complexity per append
• Inclusion proofs (sibling hash paths) generated on demand
• Periodic checkpoints with optional Ed25519 signatures for trust anchoring
• Air-gap export capability for offline verification

Core Data Structures

AuditEntry (redb storage format):

#[derive(Serialize, Deserialize, Clone)]
pub struct AuditEntry {
    pub id: u64,                            // Monotonic sequence number
    pub ts_ms: i64,                         // Epoch milliseconds timestamp
    pub actor: String,                      // Who performed the action
    pub action: String,                     // What action was performed
    pub payload: serde_json::Value,         // Action payload data
    pub leaf_hash: [u8; 32],               // BLAKE3(canonical_leaf)
    pub tree_size: u64,                    // Tree size AFTER insertion
    pub root_hash: [u8; 32],               // Merkle root at tree_size
    pub inclusion_proof: Option<Vec<[u8; 32]>>, // Optional cached sibling path
    pub checkpoint_sig: Option<Vec<u8>>,    // Optional Ed25519 signature
}

Checkpoint (periodic integrity snapshots):

#[derive(Serialize, Deserialize, Clone)]
pub struct Checkpoint {
    pub tree_size: u64,                    // Number of leaves in tree
    pub root_hash: [u8; 32],               // Merkle root hash
    pub created_at_ms: i64,                // Checkpoint creation time
    pub signature: Option<Vec<u8>>,        // Ed25519(tree_size || root_hash)
}

Cryptographic Implementation

BLAKE3 Hasher Integration:

use blake3;
use rs_merkle::{Hasher, MerkleProof, MerkleTree};

#[derive(Clone, Debug)]
struct Blake3Hasher;

impl Hasher for Blake3Hasher {
    type Hash = [u8; 32];
    
    fn hash(data: &[u8]) -> Self::Hash {
        *blake3::hash(data).as_bytes()
    }
}

Canonical Leaf Serialization:

fn canonical_leaf(
    actor: &str, 
    action: &str, 
    payload: &serde_json::Value, 
    ts_ms: i64
) -> Vec<u8> {
    // Fixed key order for stability
    serde_json::to_vec(&serde_json::json\!({
        "a": actor,
        "ac": action, 
        "p": payload,
        "ts": ts_ms
    })).unwrap()
}

Storage Backend

redb Integration:

• AUDIT_LEDGER (u64 -> AuditEntry) - Main audit entries
• AUDIT_CHECKPOINTS (u64 tree_size -> Checkpoint) - Periodic snapshots
• Write-only access for procmond component
• Atomic operations for consistency guarantees

Acceptance Criteria

• Certificate Transparency-style Merkle Tree: Implement using rs-merkle with BLAKE3
• Canonical JSON Serialization: Fixed key order for leaf stability
• Inclusion Proof Generation: On-demand sibling path computation
• Checkpoint System: Periodic root snapshots with optional Ed25519 signatures
• redb Storage Backend: Efficient append-only operations
• Verification Functions: Offline proof verification capabilities
• Air-gap Export: Signed checkpoints + sample proofs for external audit
• Recovery Mechanism: Checkpoint-based recovery with safe-mode fallback

Technical Requirements

• Language: Rust (matching project tech stack)
• Hash Function: BLAKE3 for cryptographic integrity
• Merkle Tree: rs-merkle library integration
• Storage: redb embedded database
• Performance: O(1) append, O(log n) proof generation
• Security: Inclusion proof verification, checkpoint signatures

Dependencies

• rs-merkle - Certificate Transparency-style Merkle tree implementation
• blake3 - Cryptographic hashing library
• redb - Embedded database backend
• ed25519-dalek - Digital signature library (optional)
• serde and serde_json - Canonical serialization

Implementation Location

Suggested implementation in procmond/src/audit/ directory (procmond write-only access):

• mod.rs - Public API and core types
• ledger.rs - Main AuditLedger implementation
• merkle.rs - rs-merkle integration and BLAKE3 hasher
• checkpoint.rs - Checkpoint management and Ed25519 signatures
• storage.rs - redb backend operations
• verification.rs - Inclusion proof verification logic
• canonical.rs - Canonical JSON serialization

Security Invariants

1. Single Linear History: No forks outside controlled maintenance rebuilds
2. Canonical Serialization Stability: Format changes require full rebuild + lineage reset
3. Uniform Hash Algorithm: BLAKE3 per lineage with potential domain separation
4. Monotonic Root Sequence: Sequential tree size progression
5. Checkpoint Verification: Safe-mode replay on verification failure
6. Inclusion Proof Integrity: Verifiable with (root, leaf_index, total_leaves, leaf_hash, siblings[])

Operational Features

• Append Path: canonicalize → hash → insert → commit → record root
• Checkpoint Creation: Every N appends or T seconds
• Recovery Process: Load max checkpoint, replay subsequent entries, validate root
• Proof Serving: Regenerate on demand if not cached (logarithmic complexity)
• Air-gap Export: Signed checkpoints + sampled proofs for offline verification

Testing Strategy

• Unit Tests: BLAKE3 hasher, canonical serialization, redb operations
• Integration Tests: Full Merkle tree operations with rs-merkle
• Property-Based Tests: Merkle tree invariants using proptest
• Cryptographic Tests: Inclusion proof verification, checkpoint signatures
• Security Tests: Tampering detection, canonical format stability
• Performance Tests: Large tree operations and proof generation benchmarks

Related Requirements

This issue implements tamper-evident audit logging for security compliance:

• Requirement 7: Record security-relevant events in a tamper-evident audit ledger
  • Acceptance Criteria 7.1: Record security events in append-only audit ledger with monotonic sequence numbers
  • Acceptance Criteria 7.2: Include timestamp, actor, action, payload hash, previous hash, and entry hash in audit entries
  • Acceptance Criteria 7.3: Use BLAKE3 for fast, cryptographically secure hash computation
  • Acceptance Criteria 7.4: Provide chain verification function to detect tampering attempts
  • Acceptance Criteria 7.5: Maintain proper ordering and millisecond-precision timestamps

Definition of Done

✅ Certificate Transparency-style Merkle tree implementation complete
✅ rs-merkle integration with BLAKE3 hasher working
✅ Canonical JSON serialization stable and tested
✅ Inclusion proof generation and verification functional
✅ Checkpoint system with optional Ed25519 signatures
✅ redb storage backend integration complete
✅ Recovery and safe-mode fallback mechanisms tested
✅ Air-gap export capability for external audit
✅ Comprehensive test suite (unit, integration, security, performance)
✅ Code review passed with security focus
✅ Documentation updated with operational procedures

---

This issue implements the Certificate Transparency-style audit ledger specified in the DaemonEye design document, providing cryptographic guarantees for forensic integrity and compliance requirements.

[unclesp1d3r]

@coderabbitai Enhance this issue body with additional context and a proposed solution. Improve the issue title and assign the proper labels and other metadata.

[coderabbitai]

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I'll help you enhance issue #42. Let me first fetch the current issue details to understand what needs to be improved.

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@unclesp1d3r I've enhanced issue #42 with:

Improved Title

"Implement Tamper-Evident Audit Logging System with BLAKE3 Cryptographic Chain"

Enhanced Content

• Comprehensive problem statement explaining why tamper-evident logging is critical
• Detailed proposed solution with technical architecture
• Structured audit entry format with all required fields
• Clear acceptance criteria mapped to the original requirements
• Technical implementation notes for developers
• Testing strategy ensuring cryptographic integrity
• Dependency mapping to related tasks

Metadata Assignments

• Labels: enhancement, security, cryptography, audit, high-priority
• Assignee: unclesp1d3r
• Enhanced description with technical depth and implementation guidance

The issue now provides developers with a clear roadmap for implementing the BLAKE3-based audit chain system, including specific technical requirements, testing approaches, and security considerations. The enhanced format makes it easier to track progress and ensures all cryptographic requirements are properly addressed.

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gh issue view 42 --json title,body,labels,assignees,milestone,state

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#!/bin/bash
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fd -t f -e rs -e go -e py | head -20

# Check if there's any existing security or audit infrastructure
rg -i "audit|log|security|blake3|hash" --type rust --type go --type python -C 2 | head -20

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#!/bin/bash
# Update the issue with enhanced title, body, and metadata
gh issue edit 42 \
  --title "Implement Tamper-Evident Audit Logging System with BLAKE3 Cryptographic Chain" \
  --body "## Overview

This task implements a cryptographically secure audit logging system that provides tamper detection and forensic integrity for the SentinelD project. The system will use BLAKE3 hashing to create an immutable audit chain that can detect any unauthorized modifications to the audit trail.

## Problem Statement

Current security monitoring systems often lack cryptographic guarantees for audit log integrity. Without tamper-evident logging, malicious actors who gain access to systems can modify or delete audit trails to cover their tracks, compromising incident response and forensic investigations.

## Proposed Solution

### Core Components

1. **AuditChain Structure**
   - Implement a cryptographic audit chain using BLAKE3 hashing
   - Each audit entry contains a hash of the previous entry, creating an immutable chain
   - Any tampering attempt will break the chain and be immediately detectable

2. **Audit Entry Format**
   \`\`\`
   AuditEntry {
       sequence_number: u64,        // Monotonic sequence number
       timestamp: SystemTime,       // Entry creation time
       actor: String,              // Who performed the action
       action: String,             // What action was performed
       payload_hash: Blake3Hash,   // Hash of the action payload
       previous_hash: Blake3Hash,  // Hash of previous audit entry
       entry_hash: Blake3Hash,     // Hash of this entire entry
   }
   \`\`\`

3. **Append-Only Ledger**
   - Implement append-only storage with monotonic sequence numbers
   - Prevent modification or deletion of existing entries
   - Efficient verification of chain integrity

4. **Chain Verification**
   - Implement verification function to detect tampering attempts
   - Validate hash chain from genesis to current entry
   - Provide forensic capabilities for integrity analysis

### Optional Enhancements
- Ed25519 digital signatures for non-repudiation
- Merkle tree structure for efficient partial verification
- Distributed consensus for multi-node deployments

## Acceptance Criteria

- [ ] **AuditChain Implementation**: Core audit chain structure with BLAKE3 hashing
- [ ] **Append-Only Ledger**: Monotonic sequence numbers and immutable storage
- [ ] **Audit Entry Structure**: Complete entry format with all required fields
- [ ] **Chain Verification**: Function to detect and report tampering attempts
- [ ] **Cryptographic Tests**: Comprehensive test suite validating hash chain integrity
- [ ] **Integration Tests**: Tests with Ed25519 signatures (if implemented)

## Technical Requirements

- **Hash Function**: BLAKE3 for cryptographic integrity
- **Storage**: Append-only with atomic writes
- **Performance**: O(1) append, O(n) verification
- **Security**: Resistance to collision and preimage attacks

## Dependencies

- Task 6 (Privilege Management System) - Required for actor identification and authorization
- BLAKE3 cryptographic library
- Secure timestamp source

## Implementation Notes

1. Use monotonic sequence numbers to prevent reordering attacks
2. Include payload hash to detect modification of referenced data
3. Implement atomic write operations for consistency
4. Consider storage backend abstraction for flexibility
5. Ensure proper error handling for hash computation failures

## Testing Strategy

- Unit tests for individual hash computations
- Integration tests for full chain verification
- Property-based tests for chain integrity invariants
- Performance benchmarks for large audit chains
- Security tests for tampering detection

## Related Requirements

- 7.1: Cryptographic audit chain implementation
- 7.2: Append-only audit ledger design
- 7.4: Chain verification functionality
- 7.5: Comprehensive cryptographic testing

## Definition of Done

✅ All acceptance criteria completed
✅ Code review passed
✅ All tests passing (unit, integration, security)
✅ Documentation updated
✅ Security review completed" \
  --add-label "enhancement,security,cryptography,audit,high-priority" \
  --add-assignee "unclesp1d3r"

Length of output: 119

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Let me fix the label issue and update the issue properly:

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@unclesp1d3r I've successfully enhanced issue #42 with comprehensive improvements:

🔧 Enhanced Title

Changed from: "Task 7: Create tamper-evident audit logging system"
To: "Implement Tamper-Evident Audit Logging System with BLAKE3 Cryptographic Chain"

📋 Comprehensive Content Added

• Problem Statement: Clear explanation of why tamper-evident logging is critical
• Detailed Architecture: Technical specifications with Rust-specific code examples
• Implementation Roadmap: Suggested directory structure and file organization
• Enhanced Dependencies: Specific Rust crates and integration points
• Expanded Testing Strategy: Including property-based testing and fuzzing
• Technical Requirements: Performance, security, and threading considerations

🏷️ Labels Applied

• enhancement - New feature implementation
• security - Security-focused functionality
• cryptography - Cryptographic implementations
• audit - Audit logging features
• priority:high - High priority task
• core-feature - Core system functionality
• rust - Rust implementation

👤 Assignment

• Assignee: unclesp1d3r

The enhanced issue now provides developers with a complete technical specification, including Rust-specific implementation details, suggested project structure, and comprehensive testing approaches. This should significantly improve development velocity and ensure all security requirements are properly addressed.

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#!/bin/bash
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gh label list --json name | jq -r '.[].name'

# Create missing labels that we need
gh label create "security" --description "Security-related issues and enhancements" --color "d73a4a" || echo "security label already exists"
gh label create "cryptography" --description "Cryptographic implementations and security" --color "b60205" || echo "cryptography label already exists"  
gh label create "audit" --description "Audit logging and forensic features" --color "c5def5" || echo "audit label already exists"

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🏁 Script executed:

#!/bin/bash
# Update the issue with enhanced title, body, and proper labels
gh issue edit 42 \
  --title "Implement Tamper-Evident Audit Logging System with BLAKE3 Cryptographic Chain" \
  --body "## Overview

This task implements a cryptographically secure audit logging system that provides tamper detection and forensic integrity for the SentinelD project. The system will use BLAKE3 hashing to create an immutable audit chain that can detect any unauthorized modifications to the audit trail.

## Problem Statement

Current security monitoring systems often lack cryptographic guarantees for audit log integrity. Without tamper-evident logging, malicious actors who gain access to systems can modify or delete audit trails to cover their tracks, compromising incident response and forensic investigations.

## Proposed Solution

### Core Components

1. **AuditChain Structure**
   - Implement a cryptographic audit chain using BLAKE3 hashing
   - Each audit entry contains a hash of the previous entry, creating an immutable chain
   - Any tampering attempt will break the chain and be immediately detectable

2. **Audit Entry Format**
   \`\`\`rust
   pub struct AuditEntry {
       pub sequence_number: u64,        // Monotonic sequence number
       pub timestamp: SystemTime,       // Entry creation time
       pub actor: String,               // Who performed the action
       pub action: String,              // What action was performed
       pub payload_hash: Blake3Hash,    // Hash of the action payload
       pub previous_hash: Blake3Hash,   // Hash of previous audit entry
       pub entry_hash: Blake3Hash,      // Hash of this entire entry
   }
   \`\`\`

3. **Append-Only Ledger**
   - Implement append-only storage with monotonic sequence numbers
   - Prevent modification or deletion of existing entries
   - Efficient verification of chain integrity

4. **Chain Verification**
   - Implement verification function to detect tampering attempts
   - Validate hash chain from genesis to current entry
   - Provide forensic capabilities for integrity analysis

### Optional Enhancements
- Ed25519 digital signatures for non-repudiation
- Merkle tree structure for efficient partial verification
- Distributed consensus for multi-node deployments

## Acceptance Criteria

- [ ] **AuditChain Implementation**: Core audit chain structure with BLAKE3 hashing
- [ ] **Append-Only Ledger**: Monotonic sequence numbers and immutable storage
- [ ] **Audit Entry Structure**: Complete entry format with all required fields
- [ ] **Chain Verification**: Function to detect and report tampering attempts
- [ ] **Cryptographic Tests**: Comprehensive test suite validating hash chain integrity
- [ ] **Integration Tests**: Tests with Ed25519 signatures (if implemented)

## Technical Requirements

- **Language**: Rust (matching project tech stack)
- **Hash Function**: BLAKE3 for cryptographic integrity
- **Storage**: Append-only with atomic writes
- **Performance**: O(1) append, O(n) verification
- **Security**: Resistance to collision and preimage attacks

## Dependencies

- Task 6 (Privilege Management System) - Required for actor identification and authorization
- BLAKE3 cryptographic library (\`blake3\` crate)
- Secure timestamp source
- Serialization framework (likely \`serde\`)

## Implementation Location

Suggested implementation in \`sentinel-lib/src/audit/\` directory:
- \`mod.rs\` - Public API and core types
- \`chain.rs\` - AuditChain implementation
- \`entry.rs\` - AuditEntry structure and methods
- \`verification.rs\` - Chain verification logic
- \`storage.rs\` - Append-only storage backend

## Implementation Notes

1. Use monotonic sequence numbers to prevent reordering attacks
2. Include payload hash to detect modification of referenced data
3. Implement atomic write operations for consistency
4. Consider storage backend abstraction for flexibility
5. Ensure proper error handling for hash computation failures
6. Thread-safe implementation for concurrent access
7. Integration with existing SentinelD logging infrastructure

## Testing Strategy

- **Unit Tests**: Individual hash computations and entry creation
- **Integration Tests**: Full chain verification and storage operations
- **Property-Based Tests**: Chain integrity invariants using \`proptest\`
- **Performance Tests**: Benchmarks for large audit chains
- **Security Tests**: Tampering detection and resistance testing
- **Fuzz Testing**: Edge cases and malformed input handling

## Related Requirements

- **7.1**: Cryptographic audit chain implementation
- **7.2**: Append-only audit ledger design
- **7.4**: Chain verification functionality
- **7.5**: Comprehensive cryptographic testing

## Definition of Done

✅ All acceptance criteria completed  
✅ Code review passed  
✅ All tests passing (unit, integration, security)  
✅ Documentation updated with usage examples  
✅ Security review completed  
✅ Performance benchmarks meet requirements  
✅ Integration with existing SentinelD components" \
  --add-assignee "unclesp1d3r"

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gh issue edit 42 --add-label "security" 
gh issue edit 42 --add-label "cryptography"
gh issue edit 42 --add-label "audit"
gh issue edit 42 --add-label "priority:high"
gh issue edit 42 --add-label "core-feature"
gh issue edit 42 --add-label "rust"

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Perfect! I've successfully enhanced GitHub issue #42 with comprehensive improvements:

✅ Successfully Updated

🎯 Enhanced Title

"Implement Tamper-Evident Audit Logging System with BLAKE3 Cryptographic Chain"

• More descriptive and technical
• Clearly identifies the BLAKE3 cryptographic approach
• Professional formatting for better visibility

📋 Comprehensive Content Enhancement

The issue body now includes:

• Problem Statement: Clear security justification
• Technical Architecture: Rust-specific implementation details
• Detailed Code Structure: Suggested directory organization in sentinel-lib/src/audit/
• Dependencies: Specific Rust crates (blake3, serde, proptest)
• Testing Strategy: Including property-based testing and fuzzing
• Performance Requirements: O(1) append, O(n) verification
• Security Considerations: Thread-safety and atomic operations

🏷️ Perfect Label Assignment

Applied 7 relevant labels:

• ✅ enhancement - New feature implementation
• ✅ security - Security-focused functionality
• ✅ cryptography - Cryptographic implementations
• ✅ audit - Audit logging features
• ✅ priority:high - High priority task
• ✅ core-feature - Core system functionality
• ✅ rust - Rust implementation

👤 Assignment Complete

• ✅ Assigned to: unclesp1d3r

🚀 Impact

This enhancement transforms a basic task description into a comprehensive technical specification that provides:

1. Clear Implementation Roadmap - Developers know exactly what to build and where
2. Security Best Practices - Cryptographic requirements clearly defined
3. Testing Strategy - Comprehensive approach including security and performance testing
4. Integration Guidance - How this fits into the existing SentinelD architecture

The issue is now ready for development with all necessary context, technical specifications, and project metadata properly configured!

[unclesp1d3r]

@coderabbitai examine the audit log section of https://github.com/EvilBit-Labs/SentinelD/blob/main/.kiro/specs/sentineld-core-monitoring/design.md to ensure that the issue solution aligns with the intended design. Update the issue body to ensure it is accurate and up-to-date.