mpc/examples/tfhe/main.go

// Copyright (c) 2024-2025 Hanzo AI Inc.
// SPDX-License-Identifier: BSD-3-Clause

// TFHE (Threshold Fully Homomorphic Encryption) Example
// Demonstrates FHE computations on encrypted data with threshold decryption
package main

import (
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"log"
	"math/big"
)

func main() {
	fmt.Println("=== TFHE (Threshold Fully Homomorphic Encryption) Example ===")
	fmt.Println()

	// Note: This example demonstrates the concepts and API usage.
	// Full TFHE requires the luxfi/fhe package to be properly configured.

	// Define MPC nodes with 2-of-3 threshold
	partyIDs := []string{"node1", "node2", "node3"}
	thresholdValue := 1 // 2-of-3 threshold (t+1 signers required)

	fmt.Println("1. TFHE Key Generation (Threshold)")
	fmt.Println("   Protocol: Threshold FHE Key Generation")
	fmt.Println("   Use case: Distributed encryption/decryption with computation")
	fmt.Println()

	// Simulate TFHE key generation
	tfheKeyGen := &TFHEKeyGenSession{
		PartyIDs:  partyIDs,
		Threshold: thresholdValue,
		SessionID: generateSessionID(),
	}

	fmt.Printf("   ✓ Session ID: %s\n", tfheKeyGen.SessionID[:16]+"...")
	fmt.Printf("   ✓ Parties: %v\n", tfheKeyGen.PartyIDs)
	fmt.Printf("   ✓ Threshold: %d-of-%d\n", thresholdValue+1, len(partyIDs))
	fmt.Println()

	// Example 2: Encrypted Computation
	fmt.Println("2. Homomorphic Computation Example")
	fmt.Println("   Operation: Encrypted addition and multiplication")
	fmt.Println()

	// Simulate encrypted values
	plaintext1 := big.NewInt(42)
	plaintext2 := big.NewInt(17)

	// In real TFHE, these would be ciphertexts
	encrypted1 := simulateEncrypt(plaintext1)
	encrypted2 := simulateEncrypt(plaintext2)

	fmt.Printf("   ✓ Value 1 (plaintext): %d\n", plaintext1)
	fmt.Printf("   ✓ Value 2 (plaintext): %d\n", plaintext2)
	fmt.Printf("   ✓ Encrypted 1: %s...\n", hex.EncodeToString(encrypted1[:16]))
	fmt.Printf("   ✓ Encrypted 2: %s...\n", hex.EncodeToString(encrypted2[:16]))
	fmt.Println()

	// Homomorphic operations (simulated)
	encryptedSum := simulateHomomorphicAdd(encrypted1, encrypted2)
	encryptedProduct := simulateHomomorphicMul(encrypted1, encrypted2)

	fmt.Printf("   ✓ Encrypted Sum: %s...\n", hex.EncodeToString(encryptedSum[:16]))
	fmt.Printf("   ✓ Encrypted Product: %s...\n", hex.EncodeToString(encryptedProduct[:16]))
	fmt.Println()

	// Example 3: Threshold Decryption
	fmt.Println("3. Threshold Decryption")
	fmt.Printf("   Requires %d-of-%d parties to decrypt\n", thresholdValue+1, len(partyIDs))
	fmt.Println()

	// Simulate partial decryption shares
	share1 := generateDecryptionShare("node1")
	share2 := generateDecryptionShare("node2")

	fmt.Printf("   ✓ Decryption share from node1: %s...\n", hex.EncodeToString(share1[:16]))
	fmt.Printf("   ✓ Decryption share from node2: %s...\n", hex.EncodeToString(share2[:16]))
	fmt.Printf("   ✓ Threshold met (2 of 3 shares)\n")
	fmt.Printf("   ✓ Decrypted sum would be: %d\n", plaintext1.Int64()+plaintext2.Int64())
	fmt.Printf("   ✓ Decrypted product would be: %d\n", plaintext1.Int64()*plaintext2.Int64())
	fmt.Println()

	// Example 4: Private Smart Contract Execution
	fmt.Println("4. Private Smart Contract Execution")
	fmt.Println("   Use case: Confidential DeFi transactions")
	fmt.Println()

	contract := &PrivateContract{
		Name:        "ConfidentialSwap",
		InputTypes:  []string{"encrypted_amount", "encrypted_price"},
		OutputTypes: []string{"encrypted_result"},
	}

	fmt.Printf("   ✓ Contract: %s\n", contract.Name)
	fmt.Printf("   ✓ Inputs: %v\n", contract.InputTypes)
	fmt.Printf("   ✓ Outputs: %v\n", contract.OutputTypes)
	fmt.Printf("   ✓ Computation runs on encrypted data\n")
	fmt.Printf("   ✓ Only threshold parties can decrypt result\n")
	fmt.Println()

	// Example 5: Encrypted Database Query
	fmt.Println("5. Encrypted Database Query")
	fmt.Println("   Use case: Private data analytics")
	fmt.Println()

	query := &EncryptedQuery{
		Operation: "SUM",
		Column:    "encrypted_balance",
		Filter:    "encrypted_age > threshold",
	}

	fmt.Printf("   ✓ Query: %s(%s) WHERE %s\n", query.Operation, query.Column, query.Filter)
	fmt.Printf("   ✓ Database never sees plaintext values\n")
	fmt.Printf("   ✓ Result is encrypted, needs threshold decryption\n")
	fmt.Println()

	// TFHE capabilities
	fmt.Println("=== TFHE Capabilities ===")
	capabilities := []struct {
		name string
		desc string
	}{
		{"Threshold Key Generation", "Distributed key generation with no single party holding full key"},
		{"Homomorphic Addition", "Add encrypted values without decryption"},
		{"Homomorphic Multiplication", "Multiply encrypted values without decryption"},
		{"Threshold Decryption", "t-of-n parties required to decrypt results"},
		{"Bootstrapping", "Refresh ciphertexts to enable unlimited operations"},
		{"SIMD Operations", "Parallel operations on encrypted vectors"},
	}
	for _, cap := range capabilities {
		fmt.Printf("   ✓ %s\n     %s\n", cap.name, cap.desc)
	}
	fmt.Println()

	// Use cases
	fmt.Println("=== TFHE Use Cases ===")
	useCases := []struct {
		name string
		desc string
	}{
		{"Private DeFi", "Confidential swaps, lending, and trading"},
		{"Healthcare", "Compute on encrypted patient data"},
		{"Finance", "Risk analysis on encrypted portfolios"},
		{"Voting", "Verifiable elections with voter privacy"},
		{"ML/AI", "Private inference on encrypted models"},
		{"Supply Chain", "Track goods without revealing business data"},
	}
	for _, uc := range useCases {
		fmt.Printf("   ✓ %s: %s\n", uc.name, uc.desc)
	}
	fmt.Println()

	fmt.Println("=== TFHE + MPC Benefits ===")
	fmt.Println("   • Computation on encrypted data (FHE)")
	fmt.Println("   • No single point of decryption (threshold)")
	fmt.Println("   • Key shares distributed across parties")
	fmt.Println("   • Verifiable computation results")
	fmt.Println("   • Post-quantum security (lattice-based)")
	fmt.Println("   • Integration with blockchain for trustless execution")
	fmt.Println()
	fmt.Println("✅ TFHE threshold computation ready!")
}

// TFHEKeyGenSession represents a threshold FHE key generation session
type TFHEKeyGenSession struct {
	PartyIDs  []string
	Threshold int
	SessionID string
}

// PrivateContract represents a confidential smart contract
type PrivateContract struct {
	Name        string
	InputTypes  []string
	OutputTypes []string
}

// EncryptedQuery represents a query on encrypted data
type EncryptedQuery struct {
	Operation string
	Column    string
	Filter    string
}

// generateSessionID creates a random session identifier
func generateSessionID() string {
	b := make([]byte, 32)
	_, err := rand.Read(b)
	if err != nil {
		log.Fatalf("Failed to generate session ID: %v", err)
	}
	return hex.EncodeToString(b)
}

// simulateEncrypt simulates FHE encryption (placeholder)
func simulateEncrypt(plaintext *big.Int) []byte {
	// In real TFHE, this would produce a ciphertext
	// Here we just create a deterministic "encrypted" representation
	result := make([]byte, 64)
	copy(result[:], plaintext.Bytes())
	// Add some "noise" to simulate encryption
	noise := make([]byte, 32)
	rand.Read(noise)
	copy(result[32:], noise)
	return result
}

// simulateHomomorphicAdd simulates homomorphic addition
func simulateHomomorphicAdd(a, b []byte) []byte {
	result := make([]byte, 64)
	// In real TFHE, this would be actual homomorphic addition
	for i := 0; i < len(a) && i < len(result); i++ {
		result[i] = a[i] ^ b[i] // XOR as placeholder
	}
	return result
}

// simulateHomomorphicMul simulates homomorphic multiplication
func simulateHomomorphicMul(a, b []byte) []byte {
	result := make([]byte, 64)
	// In real TFHE, this would be actual homomorphic multiplication
	for i := 0; i < len(a) && i < len(result); i++ {
		result[i] = a[i] & b[i] // AND as placeholder
	}
	return result
}

// generateDecryptionShare generates a simulated decryption share
func generateDecryptionShare(nodeID string) []byte {
	share := make([]byte, 32)
	rand.Read(share)
	// Include node ID in the share for demonstration
	copy(share[:len(nodeID)], []byte(nodeID))
	return share
}