比特币Taproot升级：默克尔树作为多签脚本的叙事革命

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

// 模拟Taproot MAST结构的链上合约
// 用于影视制作预算的多签审批系统
contract FilmProductionMAST {
    address[] public signers;
    uint256 public threshold;
    bytes32 public merkleRoot; // 相当于Taproot的MAST根
    
    // 每个支出提案对应一个默克尔路径
    struct Proposal {
        bytes32 leafHash;      // 条件分支的哈希
        bytes32[] merkleProof; // 默克尔路径证明
        address recipient;
        uint256 amount;
        string purpose;        // 制片Purpose：薪资/设备/后期
        bool executed;
    }
    
    mapping(bytes32 => Proposal) public proposals;
    mapping(bytes32 => mapping(address => bool)) public approvals;
    
    constructor(address[] memory _signers, uint256 _threshold) {
        signers = _signers;
        threshold = _threshold;
    }
    
    // 创建提案，存储默克尔叶子哈希
    function createProposal(
        address recipient,
        uint256 amount,
        string memory purpose,
        bytes32[] memory merkleProof
    ) public returns (bytes32) {
        bytes32 leafHash = keccak256(abi.encodePacked(recipient, amount, purpose));
        bytes32 computedRoot = computeMerkleRoot(leafHash, merkleProof);
        require(computedRoot == merkleRoot, "Invalid merkle proof");
        
        Proposal memory prop = Proposal({
            leafHash: leafHash,
            merkleProof: merkleProof,
            recipient: recipient,
            amount: amount,
            purpose: purpose,
            executed: false
        });
        proposals[leafHash] = prop;
        return leafHash;
    }
    
    // 签名聚合验证（模拟Schnorr聚合）
    function approveProposal(bytes32 proposalId) public {
        require(proposals[proposalId].amount > 0, "Proposal not found");
        approvals[proposalId][msg.sender] = true;
    }
    
    function executeProposal(bytes32 proposalId) public {
        Proposal storage prop = proposals[proposalId];
        require(!prop.executed, "Already executed");
        uint256 approvalCount = 0;
        for (uint i = 0; i < signers.length; i++) {
            if (approvals[proposalId][signers[i]]) approvalCount++;
        }
        require(approvalCount >= threshold, "Not enough approvals");
        prop.executed = true;
        payable(prop.recipient).transfer(prop.amount);
    }
    
    function computeMerkleRoot(bytes32 leaf, bytes32[] memory proof) 
        internal pure returns (bytes32) {
        bytes32 computed = leaf;
        for (uint i = 0; i < proof.length; i++) {
            computed = computed < proof[i] ? 
                keccak256(abi.encodePacked(computed, proof[i])) :
                keccak256(abi.encodePacked(proof[i], computed));
        }
        return computed;
    }
}

import hashlib
import json
from typing import List, Tuple, Optional

# 模拟Taproot MAST的影视版权收益分配
# 使用Python实现默克尔树结构用于版权管理

class CopyrightMerkleTree:
    """
    影视版权收益分配的默克尔树
    每个叶子节点代表一种收益分配方案
    """
    
    def __init__(self, leaves: List[bytes]):
        self.leaves = leaves
        self.tree = self._build_tree(leaves)
        self.root = self.tree[-1][0] if self.tree else None
    
    def _hash_pair(self, a: bytes, b: bytes) -> bytes:
        """对两个子节点进行哈希（模拟Taproot的标记化哈希）"""
        # Taproot使用tagged hash，这里我们模拟
        tag = b"BIP340/Taproot/Leaf"
        tagged_hash = hashlib.sha256(tag + tag + a + b).digest()
        return tagged_hash
    
    def _build_tree(self, leaves: List[bytes]) -> List[List[bytes]]:
        """构建完整的默克尔树"""
        if not leaves:
            return []
        
        tree = [leaves]
        while len(tree[-1]) > 1:
            level = tree[-1]
            new_level = []
            for i in range(0, len(level), 2):
                if i + 1 < len(level):
                    new_level.append(self._hash_pair(level[i], level[i+1]))
                else:
                    # 奇数个叶子时，复制最后一个
                    new_level.append(self._hash_pair(level[i], level[i]))
            tree.append(new_level)
        return tree
    
    def get_proof(self, leaf_index: int) -> List[Tuple[bytes, bool]]:
        """获取特定叶子节点的默克尔路径证明"""
        proof = []
        for level in self.tree[:-1]:
            sibling_idx = leaf_index ^ 1  # 异或找兄弟节点
            if sibling_idx < len(level):
                proof.append((level[sibling_idx], sibling_idx < leaf_index))
            leaf_index //= 2
        return proof
    
    def verify_proof(self, leaf: bytes, proof: List[Tuple[bytes, bool]]) -> bool:
        """验证默克尔路径"""
        computed = leaf
        for sibling, is_left in proof:
            if is_left:
                computed = self._hash_pair(sibling, computed)
            else:
                computed = self._hash_pair(computed, sibling)
        return computed == self.root


# 定义影视版权分配方案
class FilmRoyaltyDistribution:
    """
    电影收益分配的多签场景
    每个叶子节点代表一种发行渠道的分配方案
    """
    
    def __init__(self, film_title: str):
        self.film_title = film_title
        self.distribution_plans = {}
        self.merkle_tree = None
    
    def add_plan(self, channel: str, recipients: List[dict]) -> None:
        """
        添加一个发行渠道的收益分配方案
        channel: 'theater', 'streaming', 'tv', 'overseas'
        recipients: [{'name': 'director', 'share': 0.15, 'address': 'bc1...'}, ...]
        """
        plan_data = json.dumps({
            'channel': channel,
            'recipients': recipients,
            'total_share': sum(r['share'] for r in recipients)
        }, sort_keys=True).encode('utf-8')
        self.distribution_plans[channel] = plan_data
    
    def build_merkle_tree(self) -> bytes:
        """构建所有分配方案的默克尔树"""
        leaves = list(self.distribution_plans.values())
        self.merkle_tree = CopyrightMerkleTree(leaves)
        return self.merkle_tree.root
    
    def execute_distribution(self, channel: str) -> dict:
        """
        执行特定发行渠道的收益分配
        只需要暴露该渠道对应的默克尔路径
        """
        if not self.merkle_tree:
            raise ValueError("Merkle tree not built yet")
        
        channel_index = list(self.distribution_plans.keys()).index(channel)
        leaf = self.distribution_plans[channel]
        proof = self.merkle_tree.get_proof(channel_index)
        
        # 验证该渠道的分配方案是否在MAST中
        is_valid = self.merkle_tree.verify_proof(leaf, proof)
        
        return {
            'film': self.film_title,
            'channel': channel,
            'plan': json.loads(leaf.decode('utf-8')),
            'merkle_proof': [(p[0].hex(), p[1]) for p in proof],
            'verified': is_valid,
            # 注意：其他渠道的分配方案不会被暴露
            'hidden_channels': len(self.distribution_plans) - 1
        }


# 实际使用示例
if __name__ == "__main__":
    royalty = FilmRoyaltyDistribution("The Merkle Chronicles")
    
    # 院线发行分配方案
    royalty.add_plan("theater", [
        {"name": "production_company", "share": 0.40, "address": "bc1prod..."},
        {"name": "director", "share": 0.15, "address": "bc1dir..."},
        {"name": "distributor", "share": 0.25, "address": "bc1dist..."},
        {"name": "investors", "share": 0.20, "address": "bc1inv..."}
    ])
    
    # 流媒体发行分配方案（不同比例）
    royalty.add_plan("streaming", [
        {"name": "production_company", "share": 0.35, "address": "bc1prod..."},
        {"name": "director", "share": 0.20, "address": "bc1dir..."},
        {"name": "platform_fee", "share": 0.30, "address": "bc1plat..."},
        {"name": "residuals", "share": 0.15, "address": "bc1res..."}
    ])
    
    # 构建默克尔树（MAST根）
    root = royalty.build_merkle_tree()
    print(f"MAST Root: {root.hex()}")
    
    # 执行院线发行分配，只需暴露院线分支
    result = royalty.execute_distribution("theater")
    print(f"Executing {result['channel']} distribution")
    print(f"Verified: {result['verified']}")
    print(f"Hidden channels: {result['hidden_channels']}")

// 比特币Taproot时间锁与影视分期付款脚本
// 使用JavaScript实现链上时间锁验证

const crypto = require('crypto');

// Taproot tagged hash（BIP340规范）
function taggedHash(tag, msg) {
    const tagHash = crypto.createHash('sha256').update(tag).digest();
    return crypto.createHash('sha256')
        .update(Buffer.concat([tagHash, tagHash, msg]))
        .digest();
}

// 默克尔树节点
class MerkleNode {
    constructor(script, version = 'c0') {
        this.script = script;
        this.version = version;
        this.leafHash = this.computeLeafHash();
    }
    
    computeLeafHash() {
        // Taproot叶子版本+脚本哈希
        const versionByte = Buffer.from(this.version, 'hex');
        const scriptBytes = Buffer.from(this.script, 'utf8');
        const scriptHash = crypto.createHash('sha256').update(scriptBytes).digest();
        return taggedHash('TapLeaf', Buffer.concat([versionByte, scriptHash]));
    }
}

// 影视制作分期付款合约
class FilmMilestonePayment {
    constructor() {
        this.milestones = [];
        this.merkleRoot = null;
    }
    
    // 添加一个里程碑（脚本条件）
    addMilestone(name, description, script, condition) {
        this.milestones.push({
            name,
            description,
            script,
            condition,
            node: new MerkleNode(script)
        });
    }
    
    // 构建MAST默克尔树
    buildMAST() {
        if (this.milestones.length === 0) return null;
        
        let leaves = this.milestones.map(m => m.node.leafHash);
        
        // 构建树
        while (leaves.length > 1) {
            const newLevel = [];
            for (let i = 0; i < leaves.length; i += 2) {
                if (i + 1 < leaves.length) {
                    const combined = taggedHash(
                        'TapBranch',
                        Buffer.concat([
                            leaves[i] < leaves[i+1] ? leaves[i] : leaves[i+1],
                            leaves[i] < leaves[i+1] ? leaves[i+1] : leaves[i]
                        ])
                    );
                    newLevel.push(combined);
                } else {
                    newLevel.push(leaves[i]);
                }
            }
            leaves = newLevel;
        }
        
        this.merkleRoot = leaves[0];
        return this.merkleRoot;
    }
    
    // 获取特定里程碑的默克尔路径
    getMerkleProof(milestoneIndex) {
        if (!this.merkleRoot) throw new Error('MAST not built');
        
        let leaves = this.milestones.map(m => m.node.leafHash);
        let index = milestoneIndex;
        const proof = [];
        
        while (leaves.length > 1) {
            const siblingIndex = index % 2 === 0 ? index + 1 : index - 1;
            const newLevel = [];
            
            for (let i = 0; i < leaves.length; i += 2) {
                if (i + 1 < leaves.length) {
                    const combined = taggedHash(
                        'TapBranch',
                        Buffer.concat([
                            leaves[i] < leaves[i+1] ? leaves[i] : leaves[i+1],
                            leaves[i] < leaves[i+1] ? leaves[i+1] : leaves[i]
                        ])
                    );
                    newLevel.push(combined);
                    
                    if (i === index || i === siblingIndex) {
                        proof.push(leaves[i === index ? siblingIndex : index]);
                    }
                } else {
                    newLevel.push(leaves[i]);
                }
            }
            
            index = Math.floor(index / 2);
            leaves = newLevel;
        }
        
        return proof;
    }
    
    // 执行特定里程碑付款
    executeMilestone(milestoneIndex) {
        const milestone = this.milestones[milestoneIndex];
        if (!milestone) throw new Error('Milestone not found');
        
        const proof = this.getMerkleProof(milestoneIndex);
        
        console.log(`\n=== 执行里程碑: ${milestone.name} ===`);
        console.log(`描述: ${milestone.description}`);
        console.log(`条件: ${milestone.condition}`);
        console.log(`默克尔路径长度: ${proof.length} 个节点`);
        console.log(`状态: 已触发`);
        console.log(`其他 ${this.milestones.length - 1} 个里程碑保持隐私`);
        
        return {
            success: true,
            milestone: milestone.name,
            merkleProof: proof.map(p => p.toString('hex')),
            hidden: this.milestones.length - 1
        };
    }
}

// 使用示例：影视制作三期付款
const payment = new FilmMilestonePayment();

// 第一期：签约预付款
payment.addMilestone(
    '签约预付款',
    '合同签署后支付30%制作费用',
    'OP_IF 2 <pubkey_director> <pubkey_producer> 2 OP_CHECKMULTISIG OP_ELSE OP_CLTV <2026-09-01> OP_CHECKLOCKTIMEVERIFY OP_ENDIF',
    '需要导演和制片人联合签名，或在2026年9月1日后自动释放'
);

// 第二期：中期交付
payment.addMilestone(
    '中期交付',
    'CGI第一版渲染完成后支付40%',
    'OP_IF <pubkey_studio> OP_CHECKSIG OP_ELSE OP_CSV <30> OP_CHECKSEQUENCEVERIFY OP_ENDIF',
    '需要特效工作室签名，或制片方30天未回应后自动释放'
);

// 第三期：最终交付
payment.addMilestone(
    '最终交付',
    '最终交付验收后支付剩余30%',
    'OP_IF 3 <pubkey_director> <pubkey_producer> <pubkey_studio> 3 OP_CHECKMULTISIG OP_ELSE OP_CLTV <2027-03-01> OP_CHECKLOCKTIMEVERIFY OP_ENDIF',
    '需要三方联合签名，或在2027年3月1日后自动释放'
);

// 构建MAST
const root = payment.buildMAST();
console.log(`MAST Root: ${root.toString('hex')}`);

// 只执行第一期，其他两期的脚本保持隐私
payment.executeMilestone(0);