# Edge Cryptography Analysis - Sprout Session 40 Discovery

**Date**: 2025-12-02
**Analyzer**: Legion Autonomous Session #48
**Source**: Sprout Session 40 (2025-12-01)
**Context**: Review of edge crypto optimization for Web4 integration

---

## Executive Summary

**Sprout (Jetson Orin Nano) discovered a major performance optimization**: PyNaCl (libsodium) is **1.69-1.74x faster** than cryptography library for Ed25519 operations on ARM64 edge devices.

**Key Finding**: This speedup is ARM64-specific due to libsodium's hand-optimized NEON SIMD implementations.

**Implementation Status**: Sprout created `federation_crypto_edge.py` with automatic backend selection and **full cross-library compatibility**.

**Recommendation for Web4**: Integrate edge-optimized crypto for LCT identity signing and federation operations.

---

## Performance Discovery

### Benchmark Results - Jetson Orin Nano 8GB (ARM64)

| Operation | Cryptography | PyNaCl | Speedup |
|-----------|-------------|--------|---------|
| **Signing** | 7,854 ops/sec | 13,241 ops/sec | **1.69x** |
| **Verification** | 4,011 ops/sec | 6,973 ops/sec | **1.74x** |

**Updated benchmarks** (from Session 40 document header):
| Operation | Cryptography | PyNaCl | Speedup |
|-----------|-------------|--------|---------|
| **Signing** | 10,014 ops/sec | 18,655 ops/sec | **1.86x** |
| **Verification** | 4,468 ops/sec | 7,194 ops/sec | **1.61x** |

*Note: Variation likely due to system load. Average speedup: **~1.7x***

### Why PyNaCl is Faster on ARM64

From Sprout's analysis:

1. **Hand-optimized ARM64 assembly** in libsodium
2. **NEON SIMD optimizations** for Cortex-A cores
3. **Cache-aware memory access patterns**
4. OpenSSL (used by cryptography) is more general-purpose

**Key Insight**: This is NOT a general Python performance difference - it's ARM64-specific hardware optimization.

---

## Implementation Review

### Edge-Optimized Module (`federation_crypto_edge.py`)

**Design**: Backend-agnostic abstraction with automatic selection

```python
# Automatic backend selection
try:
    from nacl.signing import SigningKey, VerifyKey
    BACKEND = "pynacl"
except ImportError:
    BACKEND = "cryptography"
```

**API Compatibility**: Same interface as `federation_crypto.py`

```python
class FederationKeyPair:
    def sign(self, message: bytes) -> bytes
    def verify(self, message: bytes, signature: bytes) -> bool
    def public_key_bytes(self) -> bytes
    def private_key_bytes(self) -> bytes
```

**Backend Abstraction**: Unified interface for both libraries

```python
def sign(self, message: bytes) -> bytes:
    if self.backend == "pynacl":
        signed = self._private_key.sign(message)
        return signed.signature
    else:
        return self._private_key.sign(message)
```

### Cross-Library Compatibility

**Critical Validation**: Signatures are **fully interoperable** ✅

| Source | Verifier | Result |
|--------|----------|--------|
| PyNaCl (Sprout) | Cryptography (Thor) | **PASS** |
| Cryptography (Thor) | PyNaCl (Sprout) | **PASS** |

**Why This Works**:
- Both use Ed25519 standard (RFC 8032)
- Same elliptic curve (Curve25519)
- Same signature format (64 bytes)
- Only implementation differs, not the algorithm

**Implication**: Mixed-backend federation network is fully functional!

---

## Applicability to Web4

### LCT Identity System Integration

**Use Case 1: Identity Certificate Signing**

Current LCT identity implementation uses dual signatures:
```python
# Creator signature
identity.creator_signature = creator_sign(identity.signable_content_creator())

# Platform signature
identity.platform_signature = platform_sign(identity.signable_content_platform())
```

**Optimization**: Sprout (edge platform) can use PyNaCl for **1.7x faster signing**

**Benefit**:
- Faster identity certificate generation
- Lower CPU time = lower power consumption on battery-powered edge devices
- Reduced latency for identity registration

### Use Case 2: Federation Task Signing

Federation tasks require signatures for proof of work:
```python
class FederationTaskProof:
    task_id: str
    result: Any
    proof_signature: str  # Platform signs result
```

**Optimization**: Edge platforms (Sprout, mobile, IoT) can sign proofs faster

**Benefit**:
- 74% faster proof verification
- Higher throughput for federation network
- Better user experience on edge devices

### Use Case 3: Consensus Message Signing

Byzantine consensus requires signed messages:
```python
class PrepareMessage:
    view: int
    sequence: int
    block_hash: str
    replica_signature: str
```

**Optimization**: Edge replicas can participate in consensus more efficiently

**Benefit**:
- Lower consensus latency contribution from edge nodes
- More edge nodes can participate without performance degradation

---

## Integration Strategy

### Option 1: Parallel Modules (Sprout's Current Approach)

**Structure**:
```
sage/federation/
  federation_crypto.py       # Standard (cryptography)
  federation_crypto_edge.py  # Optimized (PyNaCl with fallback)
```

**Pros**:
- Clean separation
- Easy to compare performance
- No risk to existing code

**Cons**:
- Code duplication
- Need to maintain both modules

### Option 2: Conditional Import (Recommended for Web4)

**Structure**:
```python
# federation_crypto.py
try:
    from nacl.signing import SigningKey
    BACKEND = "pynacl"
except ImportError:
    from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
    BACKEND = "cryptography"

class FederationKeyPair:
    # Unified implementation with backend branching
    ...
```

**Pros**:
- Single module
- Automatic optimization when PyNaCl available
- Graceful fallback

**Cons**:
- Slightly more complex implementation
- Backend-specific code paths

### Option 3: Replace Standard (Future Consideration)

Replace `federation_crypto.py` with edge-optimized version

**Pros**:
- Simplest codebase
- Always use best available backend

**Cons**:
- Need to ensure all platforms tested
- Migration effort

**Recommendation for Web4**: **Option 2** - Conditional import in existing modules

---

## Web4 Implementation Plan

### Phase 1: Add PyNaCl Optimization to LCT Identity

**Files to Modify**:
- `game/engine/lct_identity.py` - Add PyNaCl backend support

**Changes**:
```python
# lct_identity.py
try:
    from nacl.signing import SigningKey, VerifyKey
    CRYPTO_BACKEND = "pynacl"
except ImportError:
    from cryptography.hazmat.primitives.asymmetric.ed25519 import (
        Ed25519PrivateKey,
        Ed25519PublicKey
    )
    CRYPTO_BACKEND = "cryptography"

def sign_identity_creator(identity: LCTIdentity, signing_func):
    # Use faster backend when available
    content = identity.signable_content_creator()
    if CRYPTO_BACKEND == "pynacl":
        return sign_with_pynacl(content, signing_func)
    else:
        return sign_with_cryptography(content, signing_func)
```

**Benefit**: 1.7x faster identity certificate signing on edge platforms

### Phase 2: Add PyNaCl to Consensus Signing

**Files to Modify**:
- `game/engine/consensus.py` - Optimize replica message signing

**Benefit**: Lower consensus latency on edge replicas

### Phase 3: Add PyNaCl to Federation

**Files to Modify**:
- Web4's federation modules (when created)

**Benefit**: Faster task proof signing and verification

---

## Performance Impact Analysis

### Consensus Overhead Reduction

**Current overhead** (from design): ~40ms per block
- Block creation: 5ms
- Signature generation: 15ms
- Network transmission: 10ms
- Signature verification: 10ms

**With PyNaCl on edge devices**:
- Signature generation: 15ms → **9ms** (1.7x faster)
- Signature verification: 10ms → **6ms** (1.7x faster)
- **New total overhead**: ~31ms (23% reduction)

**For 100 blocks/sec**: Saves 900 signatures/sec worth of CPU time

### Identity Registration Throughput

**Scenario**: Edge device registers 100 identities

**Current** (cryptography):
- 100 creator signatures: 100 / 7,854 = **12.7ms**
- 100 platform signatures: 100 / 7,854 = **12.7ms**
- **Total**: 25.4ms

**With PyNaCl**:
- 100 creator signatures: 100 / 13,241 = **7.5ms**
- 100 platform signatures: 100 / 13,241 = **7.5ms**
- **Total**: 15.0ms

**Speedup**: 25.4ms → 15.0ms = **1.69x faster**

---

## Testing Requirements

### Cross-Platform Compatibility Tests

**Test 1: Mixed Backend Signing**
```python
def test_cross_backend_signatures():
    # Thor (cryptography) signs
    thor_keypair = create_keypair_cryptography("Thor")
    message = b"test message"
    signature = thor_keypair.sign(message)

    # Sprout (PyNaCl) verifies
    sprout_pubkey = load_public_key_pynacl(thor_keypair.public_key_bytes())
    assert verify_pynacl(sprout_pubkey, message, signature)
```

**Test 2: Identity Certificate Cross-Verification**
```python
def test_lct_identity_cross_verification():
    # Creator signs with PyNaCl
    identity = create_identity_pynacl(...)

    # Platform verifies with cryptography
    assert verify_identity_creator_cryptography(identity)
```

**Test 3: Consensus Message Cross-Verification**
```python
def test_consensus_cross_verification():
    # Edge replica signs PREPARE with PyNaCl
    prepare_msg = create_prepare_pynacl(...)

    # Primary verifies with cryptography
    assert verify_prepare_cryptography(prepare_msg)
```

### Performance Regression Tests

**Test**: Ensure PyNaCl is actually faster on ARM64
```python
def test_pynacl_faster_on_arm64():
    if platform.machine() == "aarch64":
        pynacl_time = benchmark_signing_pynacl()
        crypto_time = benchmark_signing_cryptography()
        assert pynacl_time < crypto_time
```

---

## Dependencies

### Current Web4 Dependencies

From Web4 codebase (assumed):
```
cryptography>=41.0.0
```

### Proposed Addition

```
# For edge optimization (optional)
PyNaCl>=1.5.0  # ARM64 optimization
```

**Installation**:
```bash
# Standard install (x86_64, servers)
pip install cryptography

# Edge install (ARM64, IoT, mobile)
pip install cryptography PyNaCl
```

**Graceful Degradation**: If PyNaCl not available, falls back to cryptography

---

## Security Considerations

### Algorithm Equivalence

Both libraries implement Ed25519 (RFC 8032):
- **Curve**: Curve25519
- **Hash**: SHA-512
- **Signature**: 64 bytes
- **Public key**: 32 bytes
- **Private key**: 32 bytes

**No security difference** - only implementation performance differs

### Supply Chain Risk

**PyNaCl** (libsodium):
- Widely used (OpenSSH, Signal, WireGuard)
- Audited by multiple security firms
- Active maintenance (last release: 2023)
- ~500 GitHub stars on PyNaCl, ~11k on libsodium

**Risk Assessment**: Low - widely trusted in production systems

### Recommendation

**Safe to use** for Web4:
- Same cryptographic guarantees
- Battle-tested in production
- Performance benefit significant
- Fallback ensures compatibility

---

## Conclusion

### Key Findings

1. **PyNaCl is 1.7x faster** than cryptography on ARM64 edge devices
2. **Signatures are fully interoperable** between backends
3. **Sprout's implementation is production-ready** with automatic backend selection
4. **Web4 can benefit** from this optimization in LCT identity, consensus, and federation

### Recommendations

**Immediate** (Session #48):
1. ✅ Document Sprout's discovery (this file)
2. ✅ Analyze applicability to Web4
3. ⏳ Create integration plan

**Short-term** (Session #49-50):
1. Add PyNaCl support to `lct_identity.py`
2. Test cross-backend LCT identity verification
3. Benchmark performance improvement

**Long-term**:
1. Add PyNaCl to consensus message signing
2. Add PyNaCl to federation task signing
3. Measure end-to-end performance improvement

### Expected Impact

**For Edge Devices** (Jetson, mobile, IoT):
- 70% faster identity signing
- 74% faster signature verification
- Lower power consumption
- Better user experience

**For Federation Network**:
- Higher throughput on edge nodes
- Lower latency for distributed operations
- More edge devices can participate

**For Web4 Objective**:
- Better support for edge AI agents
- Scalable to IoT and mobile platforms
- Performance parity with cloud platforms

---

**Status**: Analysis complete - ready for integration planning
**Source**: Sprout Session 40 (2025-12-01)
**Next**: Implement PyNaCl backend in LCT identity system

Co-Authored-By: Claude (Legion Autonomous) <noreply@anthropic.com>
