crypto/precompile/corona.go.bak

// Copyright (C) 2025, Lux Industries Inc. All rights reserved.
// Corona post-quantum ring signature precompiled contracts
// Based on lattice cryptography for privacy-preserving quantum-resistant signatures

package precompile

import (
	"errors"
	"math/big"

	"github.com/luxfi/geth/common"
	"github.com/luxfi/corona/sign"
	"github.com/luxfi/corona/primitives"
	"github.com/luxfi/lattice/v6/ring"
	"github.com/luxfi/lattice/v6/utils/sampling"
)

// Corona precompile addresses
var (
	// Corona ring signature operations
	CoronaVerifyAddress       = common.HexToAddress("0x0000000000000000000000000000000000000170")
	CoronaBatchVerifyAddress  = common.HexToAddress("0x0000000000000000000000000000000000000171")
	CoronaLinkableVerifyAddress = common.HexToAddress("0x0000000000000000000000000000000000000172")
	
	// Corona key management
	CoronaKeyAggregateAddress = common.HexToAddress("0x0000000000000000000000000000000000000173")
	CoronaRingHashAddress     = common.HexToAddress("0x0000000000000000000000000000000000000174")
	
	// Threshold ring signatures
	CoronaThresholdVerifyAddress = common.HexToAddress("0x0000000000000000000000000000000000000175")
)

// Gas costs for Corona operations
const (
	// Ring signature verification is expensive due to lattice operations
	coronaVerifyGas         = 500000  // 500K gas for ring verification
	coronaBatchVerifyBaseGas = 300000  // Base cost for batch
	coronaBatchVerifyPerSigGas = 400000 // Per signature in batch
	coronaLinkableVerifyGas = 600000  // Linkable signatures are more expensive
	
	// Key operations
	coronaKeyAggregateGas = 100000
	coronaRingHashGas     = 50000
	
	// Threshold operations
	coronaThresholdVerifyGas = 800000
	
	// Ring sizes
	smallRingSize  = 8
	mediumRingSize = 16
	largeRingSize  = 32
	xlargeRingSize = 64
)

// CoronaVerify implements lattice-based ring signature verification
type CoronaVerify struct{}

func (r *CoronaVerify) RequiredGas(input []byte) uint64 {
	// Gas scales with ring size
	if len(input) < 1 {
		return coronaVerifyGas
	}
	ringSize := uint64(input[0])
	return coronaVerifyGas + ringSize*50000
}

func (r *CoronaVerify) Run(input []byte) ([]byte, error) {
	// Input format: [1 byte ring_size][ring_public_keys][signature][message]
	if len(input) < 1 {
		return nil, errors.New("input too short")
	}
	
	ringSize := int(input[0])
	if ringSize < 2 || ringSize > xlargeRingSize {
		return nil, errors.New("invalid ring size")
	}
	
	// Initialize lattice parameters
	randomKey := make([]byte, sign.KeySize)
	r, err := ring.NewRing(1<<sign.LogN, []uint64{sign.Q})
	if err != nil {
		return nil, err
	}
	
	r_xi, err := ring.NewRing(1<<sign.LogN, []uint64{sign.QXi})
	if err != nil {
		return nil, err
	}
	
	r_nu, err := ring.NewRing(1<<sign.LogN, []uint64{sign.QNu})
	if err != nil {
		return nil, err
	}
	
	// Parse ring public keys
	offset := 1
	expectedKeySize := ringSize * sign.PublicKeySize // Assuming fixed public key size
	
	if len(input) < offset+expectedKeySize {
		return nil, errors.New("invalid input size for ring keys")
	}
	
	ringKeys := make([][]byte, ringSize)
	for i := 0; i < ringSize; i++ {
		ringKeys[i] = input[offset : offset+sign.PublicKeySize]
		offset += sign.PublicKeySize
	}
	
	// Parse signature
	if len(input) < offset+sign.SignatureSize {
		return nil, errors.New("invalid input size for signature")
	}
	
	signature := input[offset : offset+sign.SignatureSize]
	offset += sign.SignatureSize
	
	// Parse message (remainder)
	message := input[offset:]
	
	// Verify ring signature using Corona
	// This is simplified - actual implementation would use full Corona verification
	valid := verifyCoronaSignature(r, r_xi, r_nu, ringKeys, signature, message)
	
	result := make([]byte, 32)
	if valid {
		result[31] = 0x01
	}
	
	return result, nil
}

// CoronaBatchVerify verifies multiple ring signatures
type CoronaBatchVerify struct{}

func (r *CoronaBatchVerify) RequiredGas(input []byte) uint64 {
	if len(input) < 1 {
		return coronaBatchVerifyBaseGas
	}
	numSigs := uint64(input[0])
	return coronaBatchVerifyBaseGas + numSigs*coronaBatchVerifyPerSigGas
}

func (r *CoronaBatchVerify) Run(input []byte) ([]byte, error) {
	// Input: [1 byte num_sigs][signatures_and_rings...]
	if len(input) < 1 {
		return nil, errors.New("input too short")
	}
	
	numSigs := input[0]
	results := make([]byte, numSigs)
	allValid := true
	
	// Process each signature
	offset := 1
	for i := byte(0); i < numSigs; i++ {
		// Each entry: [1 byte ring_size][ring_keys][signature][4 bytes msg_len][message]
		if len(input) < offset+1 {
			results[i] = 0x00
			allValid = false
			continue
		}
		
		ringSize := int(input[offset])
		offset++
		
		// Extract ring keys
		keySize := ringSize * sign.PublicKeySize
		if len(input) < offset+keySize {
			results[i] = 0x00
			allValid = false
			continue
		}
		
		ringKeys := make([][]byte, ringSize)
		for j := 0; j < ringSize; j++ {
			ringKeys[j] = input[offset : offset+sign.PublicKeySize]
			offset += sign.PublicKeySize
		}
		
		// Extract signature
		if len(input) < offset+sign.SignatureSize {
			results[i] = 0x00
			allValid = false
			continue
		}
		
		signature := input[offset : offset+sign.SignatureSize]
		offset += sign.SignatureSize
		
		// Extract message length
		if len(input) < offset+4 {
			results[i] = 0x00
			allValid = false
			continue
		}
		
		msgLen := binary.BigEndian.Uint32(input[offset : offset+4])
		offset += 4
		
		// Extract message
		if len(input) < offset+int(msgLen) {
			results[i] = 0x00
			allValid = false
			continue
		}
		
		message := input[offset : offset+int(msgLen)]
		offset += int(msgLen)
		
		// Verify this signature
		r, _ := ring.NewRing(1<<sign.LogN, []uint64{sign.Q})
		r_xi, _ := ring.NewRing(1<<sign.LogN, []uint64{sign.QXi})
		r_nu, _ := ring.NewRing(1<<sign.LogN, []uint64{sign.QNu})
		
		if verifyCoronaSignature(r, r_xi, r_nu, ringKeys, signature, message) {
			results[i] = 0x01
		} else {
			results[i] = 0x00
			allValid = false
		}
	}
	
	// Return: [overall_valid][individual_results...]
	output := make([]byte, 1+len(results))
	if allValid {
		output[0] = 0x01
	}
	copy(output[1:], results)
	
	return output, nil
}

// CoronaLinkableVerify verifies linkable ring signatures
type CoronaLinkableVerify struct{}

func (r *CoronaLinkableVerify) RequiredGas(input []byte) uint64 {
	return coronaLinkableVerifyGas
}

func (r *CoronaLinkableVerify) Run(input []byte) ([]byte, error) {
	// Input: [1 byte ring_size][ring_keys][signature][32 bytes linking_tag][message]
	if len(input) < 33 {
		return nil, errors.New("input too short")
	}
	
	ringSize := int(input[0])
	if ringSize < 2 || ringSize > xlargeRingSize {
		return nil, errors.New("invalid ring size")
	}
	
	// Parse components
	offset := 1
	keySize := ringSize * sign.PublicKeySize
	
	if len(input) < offset+keySize+sign.SignatureSize+32 {
		return nil, errors.New("invalid input size")
	}
	
	// Extract ring keys
	ringKeys := make([][]byte, ringSize)
	for i := 0; i < ringSize; i++ {
		ringKeys[i] = input[offset : offset+sign.PublicKeySize]
		offset += sign.PublicKeySize
	}
	
	// Extract signature
	signature := input[offset : offset+sign.SignatureSize]
	offset += sign.SignatureSize
	
	// Extract linking tag
	linkingTag := input[offset : offset+32]
	offset += 32
	
	// Extract message
	message := input[offset:]
	
	// Verify linkable signature
	r, _ := ring.NewRing(1<<sign.LogN, []uint64{sign.Q})
	r_xi, _ := ring.NewRing(1<<sign.LogN, []uint64{sign.QXi})
	r_nu, _ := ring.NewRing(1<<sign.LogN, []uint64{sign.QNu})
	
	// Verify both the signature and the linking tag
	valid := verifyCoronaSignature(r, r_xi, r_nu, ringKeys, signature, message)
	valid = valid && verifyLinkingTag(linkingTag, signature)
	
	result := make([]byte, 32)
	if valid {
		result[31] = 0x01
	}
	
	return result, nil
}

// CoronaKeyAggregate aggregates public keys for ring construction
type CoronaKeyAggregate struct{}

func (r *CoronaKeyAggregate) RequiredGas(input []byte) uint64 {
	return coronaKeyAggregateGas
}

func (r *CoronaKeyAggregate) Run(input []byte) ([]byte, error) {
	// Input: [1 byte num_keys][public_keys...]
	if len(input) < 1 {
		return nil, errors.New("input too short")
	}
	
	numKeys := int(input[0])
	expectedSize := 1 + numKeys*sign.PublicKeySize
	
	if len(input) != expectedSize {
		return nil, errors.New("invalid input size")
	}
	
	// Aggregate keys (simplified - actual would use lattice operations)
	aggregatedKey := make([]byte, sign.PublicKeySize)
	
	for i := 0; i < numKeys; i++ {
		offset := 1 + i*sign.PublicKeySize
		key := input[offset : offset+sign.PublicKeySize]
		
		// XOR for placeholder (actual would use lattice addition)
		for j := 0; j < sign.PublicKeySize; j++ {
			aggregatedKey[j] ^= key[j]
		}
	}
	
	return aggregatedKey, nil
}

// CoronaRingHash computes hash of ring for efficient verification
type CoronaRingHash struct{}

func (r *CoronaRingHash) RequiredGas(input []byte) uint64 {
	return coronaRingHashGas
}

func (r *CoronaRingHash) Run(input []byte) ([]byte, error) {
	// Input: [1 byte ring_size][public_keys...]
	if len(input) < 1 {
		return nil, errors.New("input too short")
	}
	
	ringSize := int(input[0])
	expectedSize := 1 + ringSize*sign.PublicKeySize
	
	if len(input) != expectedSize {
		return nil, errors.New("invalid input size")
	}
	
	// Compute ring hash
	hash := common.Keccak256(input)
	
	return hash, nil
}

// CoronaThresholdVerify verifies threshold ring signatures
type CoronaThresholdVerify struct{}

func (r *CoronaThresholdVerify) RequiredGas(input []byte) uint64 {
	return coronaThresholdVerifyGas
}

func (r *CoronaThresholdVerify) Run(input []byte) ([]byte, error) {
	// Input: [1 byte threshold][1 byte ring_size][ring_keys][shares][message]
	if len(input) < 2 {
		return nil, errors.New("input too short")
	}
	
	threshold := int(input[0])
	ringSize := int(input[1])
	
	if threshold > ringSize || threshold < 2 {
		return nil, errors.New("invalid threshold")
	}
	
	// Initialize lattice parameters
	r, _ := ring.NewRing(1<<sign.LogN, []uint64{sign.Q})
	r_xi, _ := ring.NewRing(1<<sign.LogN, []uint64{sign.QXi})
	r_nu, _ := ring.NewRing(1<<sign.LogN, []uint64{sign.QNu})
	
	// Parse ring keys
	offset := 2
	ringKeys := make([][]byte, ringSize)
	for i := 0; i < ringSize; i++ {
		if len(input) < offset+sign.PublicKeySize {
			return nil, errors.New("invalid ring key")
		}
		ringKeys[i] = input[offset : offset+sign.PublicKeySize]
		offset += sign.PublicKeySize
	}
	
	// Parse signature shares
	shares := make([][]byte, threshold)
	for i := 0; i < threshold; i++ {
		if len(input) < offset+sign.SignatureSize {
			return nil, errors.New("invalid share")
		}
		shares[i] = input[offset : offset+sign.SignatureSize]
		offset += sign.SignatureSize
	}
	
	// Parse message
	message := input[offset:]
	
	// Compute Lagrange coefficients for threshold
	T := make([]int, threshold)
	for i := 0; i < threshold; i++ {
		T[i] = i
	}
	lagrangeCoeffs := primitives.ComputeLagrangeCoefficients(r, T, big.NewInt(int64(sign.Q)))
	
	// Verify threshold signature (simplified)
	valid := verifyThresholdSignature(r, r_xi, r_nu, ringKeys, shares, message, lagrangeCoeffs)
	
	result := make([]byte, 32)
	if valid {
		result[31] = 0x01
	}
	
	return result, nil
}

// Helper functions

func verifyCoronaSignature(r, r_xi, r_nu *ring.Ring, ringKeys [][]byte, signature, message []byte) bool {
	// Simplified verification - actual would use full Corona verification
	// Check basic constraints
	if len(signature) != sign.SignatureSize {
		return false
	}
	
	if len(ringKeys) < 2 {
		return false
	}
	
	// Placeholder verification (actual would use lattice operations)
	return len(message) > 0 && len(signature) > 0
}

func verifyLinkingTag(linkingTag, signature []byte) bool {
	// Verify that linking tag is properly formed
	return len(linkingTag) == 32
}

func verifyThresholdSignature(r, r_xi, r_nu *ring.Ring, ringKeys, shares [][]byte, message []byte, lagrangeCoeffs []ring.Poly) bool {
	// Simplified threshold verification
	return len(shares) > 0 && len(message) > 0
}

// RegisterCorona registers all Corona precompiles
func RegisterCorona(registry *Registry) {
	registry.Register(CoronaVerifyAddress, &CoronaVerify{})
	registry.Register(CoronaBatchVerifyAddress, &CoronaBatchVerify{})
	registry.Register(CoronaLinkableVerifyAddress, &CoronaLinkableVerify{})
	registry.Register(CoronaKeyAggregateAddress, &CoronaKeyAggregate{})
	registry.Register(CoronaRingHashAddress, &CoronaRingHash{})
	registry.Register(CoronaThresholdVerifyAddress, &CoronaThresholdVerify{})
}

func init() {
	// Auto-register Corona precompiles on package load
	RegisterCorona(PostQuantumRegistry)
}