LP-4202: Cryptographic Agility Framework

Abstract

This proposal establishes a cryptographic agility framework that enables dynamic algorithm selection, seamless upgrades, and rapid response to cryptographic breakthroughs. The framework supports multiple algorithm families simultaneously, allowing the network to adapt to evolving threats without hard forks.

Motivation

Cryptographic agility is essential for long-term blockchain security:

Algorithm Breaks: Rapid response if an algorithm is compromised
Performance Evolution: Adopt faster algorithms as they emerge
Regional Compliance: Different algorithms for different jurisdictions
AI/Quantum Advances: Adapt to new computational capabilities
Zero-Day Response: Emergency algorithm swaps within hours

Specification

1. Algorithm Registry

Dynamic Algorithm Management

type AlgorithmRegistry struct {
    // Algorithm definitions
    Algorithms      map[AlgorithmID]*AlgorithmSpec
    // Security levels
    SecurityLevels  map[SecurityLevel][]AlgorithmID
    // Performance metrics
    Benchmarks      map[AlgorithmID]*PerformanceMetrics
    // Deprecation schedule
    Deprecations    map[AlgorithmID]*DeprecationNotice
    // Emergency overrides
    EmergencyMode   bool
}

type AlgorithmSpec struct {
    ID              AlgorithmID         `json:"id"`
    Family          AlgorithmFamily     `json:"family"`
    Name            string              `json:"name"`
    Version         string              `json:"version"`
    SecurityLevel   uint32              `json:"security_level"`
    QuantumSafe     bool                `json:"quantum_safe"`
    KeySize         KeySizeRange        `json:"key_size"`
    SignatureSize   uint32              `json:"signature_size"`
    Implementation  ImplementationSpec  `json:"implementation"`
    ActivationHeight uint64             `json:"activation_height"`
    Parameters      []byte              `json:"parameters"`
}

type AlgorithmFamily uint8

const (
    FamilyEllipticCurve AlgorithmFamily = 0x00  // ECDSA, EdDSA
    FamilyLattice       AlgorithmFamily = 0x01  // ML-KEM, ML-DSA
    FamilyHash          AlgorithmFamily = 0x02  // SLH-DSA, XMSS
    FamilyCode          AlgorithmFamily = 0x03  // McEliece
    FamilyMultivariate  AlgorithmFamily = 0x04  // Rainbow, UOV
    FamilyIsogeny       AlgorithmFamily = 0x05  // SIKE (broken)
    FamilySymmetric     AlgorithmFamily = 0x06  // AES, ChaCha20
    FamilyExperimental  AlgorithmFamily = 0xFF  // Research algorithms
)

Algorithm Lifecycle

Lifecycle States:
  Proposed:
    - Submitted for review
    - Testnet deployment only
    - Performance benchmarking
  
  Approved:
    - Security audit passed
    - Mainnet activation scheduled
    - Migration tools available
  
  Active:
    - Available for use
    - Full node support
    - Hardware acceleration enabled
  
  Deprecated:
    - Security concerns identified
    - Migration deadline set
    - Read-only support
  
  Removed:
    - No longer validated
    - Historical verification only
    - Archive mode required

2. Agile Signature Scheme

Multi-Algorithm Signatures

type AgileSignature struct {
    Version         uint8                   `json:"version"`
    AlgorithmID     AlgorithmID             `json:"algorithm_id"`
    PublicKeyHash   Hash256                 `json:"pubkey_hash"`
    Signature       []byte                  `json:"signature"`
    AlternateProofs []AlternateProof        `json:"alternate_proofs"`
    Metadata        SignatureMetadata       `json:"metadata"`
}

type AlternateProof struct {
    AlgorithmID AlgorithmID `json:"algorithm_id"`
    Proof       []byte      `json:"proof"`
    Weight      uint8       `json:"weight"`  // Contribution to validation
}

type SignatureMetadata struct {
    Timestamp       uint64          `json:"timestamp"`
    SecurityLevel   uint32          `json:"security_level"`
    HardwareToken   bool            `json:"hardware_token"`
    ThresholdShare  *ThresholdInfo  `json:"threshold_share,omitempty"`
}

Validation Logic

func (v *AgileValidator) Validate(
    message []byte,
    signature *AgileSignature,
    policy *ValidationPolicy,
) error {
    // Check algorithm status
    algo := v.registry.GetAlgorithm(signature.AlgorithmID)
    if algo == nil {
        return ErrUnknownAlgorithm
    }
    
    if algo.IsDeprecated() && !policy.AllowDeprecated {
        return ErrDeprecatedAlgorithm
    }
    
    // Verify signature
    verifier := v.getVerifier(signature.AlgorithmID)
    if !verifier.Verify(message, signature.Signature, signature.PublicKeyHash) {
        return ErrInvalidSignature
    }
    
    // Check security level
    if algo.SecurityLevel < policy.MinSecurityLevel {
        // Require additional proofs
        return v.validateAlternateProofs(message, signature, policy)
    }
    
    return nil
}

3. Emergency Response Protocol

Algorithm Compromise Response

type EmergencyProtocol struct {
    // Threat detection
    ThreatMonitor   *ThreatMonitor
    // Response team
    ResponseTeam    []Responder
    // Automated actions
    AutoResponse    bool
    // Migration tools
    MigrationEngine *MigrationEngine
}

func (e *EmergencyProtocol) HandleCompromise(
    algorithm AlgorithmID,
    threat ThreatLevel,
) error {
    // 1. Immediate response (< 1 minute)
    if threat >= ThreatCritical {
        e.registry.EmergencyDeprecate(algorithm)
        e.network.BroadcastAlert(AlgorithmCompromiseAlert{
            Algorithm: algorithm,
            Threat:    threat,
            Action:    "STOP_USING_IMMEDIATELY",
        })
    }
    
    // 2. Activate fallback (< 1 hour)
    fallback := e.selectFallbackAlgorithm(algorithm)
    e.registry.ActivateEmergency(fallback)
    
    // 3. Begin migration (< 24 hours)
    migration := e.MigrationEngine.CreateEmergencyMigration(
        from: algorithm,
        to:   fallback,
        deadline: time.Now().Add(7 * 24 * time.Hour),
    )
    
    // 4. Force upgrade (< 7 days)
    e.network.ScheduleHardFork(
        height: CurrentHeight() + 20160, // ~7 days
        changes: []Change{
            RemoveAlgorithm(algorithm),
            RequireAlgorithm(fallback),
        },
    )
    
    return nil
}

Quantum Threat Escalation

Quantum Threat Levels:
  Green (Safe):
    - No immediate threat
    - Continue monitoring
    - Research new algorithms
  
  Yellow (Caution):
    - Quantum progress accelerating
    - Begin migration planning
    - Activate hybrid mode
  
  Orange (Warning):
    - Credible near-term threat
    - Mandatory migration begins
    - Accelerate timeline
  
  Red (Critical):
    - Active quantum threat
    - Emergency migration
    - Disable classical crypto
  
  Black (Compromised):
    - Algorithm broken
    - Immediate shutdown
    - Emergency recovery mode

4. Performance Optimization

Adaptive Algorithm Selection

type AdaptiveSelector struct {
    // Performance history
    metrics     *MetricsDB
    // Network conditions
    network     *NetworkMonitor
    // User preferences
    preferences map[Address]AlgorithmPreference
}

func (s *AdaptiveSelector) SelectOptimal(
    context *TransactionContext,
) AlgorithmID {
    // Consider multiple factors
    factors := s.analyzeContext(context)
    
    candidates := s.registry.GetActiveAlgorithms()
    scores := make(map[AlgorithmID]float64)
    
    for _, algo := range candidates {
        score := 0.0
        
        // Security weight: 40%
        score += 0.4 * float64(algo.SecurityLevel) / 256
        
        // Performance weight: 30%
        perf := s.metrics.GetPerformance(algo.ID)
        score += 0.3 * (1.0 / perf.VerificationTime)
        
        // Size weight: 20%
        score += 0.2 * (1.0 / float64(algo.SignatureSize))
        
        // Compatibility weight: 10%
        compat := s.network.GetCompatibility(algo.ID)
        score += 0.1 * compat
        
        scores[algo.ID] = score
    }
    
    return s.selectBest(scores)
}

Hardware Acceleration Registry

type HardwareAcceleration struct {
    Algorithm   AlgorithmID
    Hardware    HardwareType
    Speedup     float64
    Available   bool
}

const (
    HardwareCPU    HardwareType = "CPU"     // AVX2, SHA extensions
    HardwareGPU    HardwareType = "GPU"     // CUDA, OpenCL
    HardwareFPGA   HardwareType = "FPGA"    // Custom circuits
    HardwareASIC   HardwareType = "ASIC"    // Dedicated chips
    HardwareQPU    HardwareType = "QPU"     // Quantum processor
)

5. Compliance and Standards

Regional Algorithm Requirements

contract RegionalCompliance {
    struct RegionalPolicy {
        bytes32 region;
        AlgorithmID[] required;
        AlgorithmID[] forbidden;
        uint256 effectiveDate;
    }
    
    mapping(bytes32 => RegionalPolicy) public policies;
    
    function validateTransaction(
        Transaction memory tx,
        bytes32 region
    ) public view returns (bool) {
        RegionalPolicy memory policy = policies[region];
        
        // Check if algorithm is allowed
        if (!isAllowed(tx.signatureAlgorithm, policy)) {
            return false;
        }
        
        // Additional regional checks
        return performRegionalChecks(tx, region);
    }
}

AI/ML Integration Points

class CryptoAgilityAI:
    def predict_algorithm_security(self, algorithm_id: str) -> SecurityPrediction:
        """
        AI model predicts future security of algorithms
        based on quantum computing progress and cryptanalysis
        """
        features = self.extract_features(algorithm_id)
        quantum_timeline = self.quantum_predictor.predict()
        
        return SecurityPrediction(
            algorithm=algorithm_id,
            safe_until=self.model.predict_break_date(features, quantum_timeline),
            confidence=self.model.confidence,
            recommendations=self.generate_recommendations()
        )
    
    def optimize_migration_strategy(self, network_state: NetworkState) -> MigrationPlan:
        """
        ML optimization for migration timing and strategy
        """
        return self.reinforcement_learner.optimize(
            state=network_state,
            objectives=[
                MinimizeDisruption(),
                MaximizeSecurity(),
                MinimizeCost()
            ]
        )

Rationale

Why Cryptographic Agility?

Future-Proof: Adapt to unforeseen developments
Risk Management: Multiple algorithms reduce single points of failure
Performance: Use optimal algorithms for each use case
Compliance: Meet evolving regulatory requirements
Innovation: Quickly adopt new algorithms

Design Principles

No Single Point of Failure: Multiple algorithm families
Graceful Degradation: System remains secure even if algorithms fail
Rapid Response: Minutes to hours, not days to weeks
User Transparency: Clear communication of changes
Backward Compatibility: Support historical verification

Backwards Compatibility

Algorithm Versioning: Clear version negotiation
Legacy Support: Old algorithms remain readable
Migration Tools: Automated upgrade assistance
Archive Nodes: Full history preservation

Test Cases

func TestCryptoAgility(t *testing.T) {
    registry := NewAlgorithmRegistry()
    
    // Add multiple algorithms
    registry.Register(ECDSA256)
    registry.Register(ML_DSA_65)
    registry.Register(SLH_DSA_192)
    
    // Test algorithm selection
    selector := NewAdaptiveSelector(registry)
    optimal := selector.SelectOptimal(context)
    assert.NotNil(t, optimal)
    
    // Test emergency deprecation
    registry.EmergencyDeprecate(ECDSA256)
    assert.True(t, registry.IsDeprecated(ECDSA256))
    
    // Test migration
    migration := NewMigration(ECDSA256, ML_DSA_65)
    assert.NoError(t, migration.Execute())
    
    // Test multi-algorithm validation
    sig := SignWithMultiple([]AlgorithmID{ML_DSA_65, SLH_DSA_192})
    assert.True(t, ValidateAgile(sig))
}

Security Considerations

Algorithm Diversity: Use algorithms from different mathematical families
Migration Security: Ensure secure transition between algorithms
Downgrade Prevention: Never allow reverting to broken algorithms
Emergency Response: Have pre-planned responses for various scenarios
Monitoring: Continuous assessment of algorithm security

Implementation Timeline

Month 1: Deploy algorithm registry
Month 2: Implement agile signatures
Month 3: Emergency response protocols
Month 4: Performance optimization
Month 5: Compliance framework
Month 6: Production deployment

Cryptographic Agility Framework