比特币中P2SH(pay-to-script-hash)多重签名的锁定脚本和解锁脚本

# P2SH(pay-to-script-hash)多重签名的脚本
P2SH是多重签名的一种应用形式。在P2SH的交易中，多了一个Redeem Script的概念，称为赎回脚本。当向P2SH脚本的地址转账时，锁定脚本中填写的不是公钥地址的列表，而是Redeem Script的hash值，这样锁定脚本变的非常短。只有在P2SH向外转账时的解锁脚本才会很长。这样就避免了多重签交易中锁定脚本过长导致交易费也骤增的问题。

一个M-N的P2SH交易，赎回脚本Redeem Script的一般形式是：
```script
OP_M <PublicKey 1> <PublicKey 2> ... <PublicKey N> OP_N OP_CHECKMULTISIG
```
锁定脚本的一般形式是：
```script
OP_HASH160 PUSHDATA(<20-byte hash of Redeem Script>) OP_EQUAL
```
解锁脚本的一般形式是：
```script
OP_0 PUSHDATA(<Signature 1>) PUSHDATA(<Signature2>) ... PUSHDATA(<Signature M>) <Redeem Script>
```

如果是一个2-3的P2SH多重签名交易，参与者为A，B，C，那么上面的三个脚本就具体成了下面的格式
赎回脚本Redeem Script：
```script
OP_2 PUSHDATA(<PublicKey A> <PublicKey B> <PublicKey C>) OP_3 OP_CHECKMULTISIG
```
锁定脚本：
```script
OP_HASH160 PUSHDATA(<20-byte hash of Redeem Script>) OP_EQUAL
```
解锁脚本（B和C发起交易）：
```script
OP_0 PUSHDATA(<Signature B>) PUSHDATA(<Signature C>) <Redeem Script>
```

# 为什么解锁脚本前面有一个空的签名OP_0？
这是由于CHECKMULTISIG执行的bug，P2SH的解锁脚本是以OP_0开始的，这里贴上《精通比特币》书中的描述：

> ![bug01](https://user-images.githubusercontent.com/7078104/40408706-07d6fc50-5e9b-11e8-911d-e5a6a3ac8f59.png)
> ![bug02 png](https://user-images.githubusercontent.com/7078104/40408712-0dc2d7d8-5e9b-11e8-8e3f-f1e0eaaaddcd.png)

# 脚本参数解释
## 脚本中的常量值
```txt
脚本中的OP_M和OP_N对应的是常量OP_1(0x51) ~ OP_16(0x60)

OP_CHECKMULTISIG=0xAE
OP_HASH160=0xA9
OP_EQUAL=0x88
```

> OP_16常量值就到头了，也就是说现在多重签名最多可以有16个人参与！

## PUSHDATA
这个在[#16](https://github.com/itlgl/note/issues/16)里面写过，这里再写一次：

```txt
如果0 < data.length < 76(0x4C)，则结果为：1个字节data.length + data数据
如果76(0x4C) <= data.length < 2^8，则结果为：0x4C + 1个字节data.length + data数据
如果2^8 <= data.length < 2^16，则结果为：0x4D + 2个字节data.length + data数据
如果2^16 <= data.length < 2^32，则结果为：0x4E + 4个字节data.length + data数据
```

## PublicKey
赎回脚本中的`<PublicKey 1>`是没有封装格式的，比如以`41`开头的非压缩格式公钥和以`21`开头的压缩格式公钥。

```txt
// 压缩格式公钥
21 03 0b461bf0f1253c9dacde9992594042d77798c5f0e7c76a1c587518606fb35478

// 非压缩格式公钥
41 04
0bf69616981e5970c992a0762f441abcadfed9fc4630fa5e1b82ab00e81d1690 // X
5d3820e073e1bd4a9dcfed336f4bf25edc634c2e174989767d299748359c2daf // Y
```

## Signature的格式
有关Signature的签名格式，参见[#16](https://github.com/itlgl/note/issues/16)里面有关`Signature的格式`的描述。

# 示例
## 锁定脚本的例子解析
附录中的示例1中有P2SH多重签名（2-3的P2SH）的锁定脚本数据：

> a9144bb8b35e3c41be76d8c0c16a3a5a398a7688e40187

按照锁定脚本解析一下（2-3的P2SH）：
```txt
// OP_HASH160 PUSHDATA(<20-byte hash of Redeem Script>) OP_EQUAL

a9 // OP_HASH160
14 // PUSHDATA，length=20
4bb8b35e3c41be76d8c0c16a3a5a398a7688e401 // 赎回脚本的hash，20字节
87 // OP_EQUAL
```

#### 赎回脚本怎么得来
其实和普通的地址相似，因为要向地址`38bPsA6ZXfRuxFD7efVXTkQd69422uzD4B`转账，所以还是从地址得到这个hash值：

将地址`38bPsA6ZXfRuxFD7efVXTkQd69422uzD4B`进行base58解码得到`054bb8b35e3c41be76d8c0c16a3a5a398a7688e401470355f0`（`0x05`表示是P2SH的地址，base58编码以后地址以3开头），将这个结果去掉头部一个字节type，去掉尾部四个字节checksum，即为赎回脚本的hash。

## 解锁脚本的例子解析
附录中的示例2中有P2SH多重签名（2-3的P2SH）的解锁脚本数据：

> 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 **// 解锁脚本，变长**

按照解锁脚本解析一下（已经不记得由哪两人发起的交易了，暂且认为是B和C发起的）：

> // OP_0 PUSHDATA(<Signature B>) PUSHDATA(<Signature C>) <Redeem Script>
> 
> 00 // OP_0
> 48 // PUSHDATA,len=72
> 3045022100bd16b2ffa112937856716909162c00a66e7c5e6cccd0093ec9aece127632f8dc02205a567c53161e5fb62ac8d202acf8f8cc2f5a6496f47a878555dae7ffde85a41d01 // signature B
> 48 // PUSHDATA,len=72
> 3045022100ac3c0365e103d97d3cc935755d5177e8f383993a558998200f8537e64f6b520002202216716f7fa54adc69095c4127ff6f97d42e28517a103f7691808db3cde6ee5b01 // signature C
> 4cc9 // PUSHDATA,len=201
> 524104a7ada7c84ae36e98735597ee770a7cfd2d5d9398154b088ee352d3a83b21bbf537c0b8e4ea0acc172285b37571a9b1e36c0da387d6d1f361f0b65cad5c3f659e4104fe411f77e5aa50b54e0f2be0204b26cd1d2bf77bf95f2108a6b012e34637289121cd351c696c8a519b4b58674a87e7907385b4a5e7c0cfa5019346c1b04040914104eeffa9bbfe6dd2c99a9747ca5d1c1ebd15fe0344f52ff2915e3c11b3be9be11236895e5514b085c1f8a1bd8ef9c3db0cf1095aaf442cae11d88c3af026fabd1653ae // Redeem Script

再按照Redeem Script的脚本解析一下Redeem Script：

> // OP_2 <PublicKey A> <PublicKey B> <PublicKey C> OP_3 OP_CHECKMULTISIG
> 
> 52 // OP_2
> 4104a7ada7c84ae36e98735597ee770a7cfd2d5d9398154b088ee352d3a83b21bbf537c0b8e4ea0acc172285b37571a9b1e36c0da387d6d1f361f0b65cad5c3f659e // PublicKey A
> 4104fe411f77e5aa50b54e0f2be0204b26cd1d2bf77bf95f2108a6b012e34637289121cd351c696c8a519b4b58674a87e7907385b4a5e7c0cfa5019346c1b0404091 // PublicKey B
> 4104eeffa9bbfe6dd2c99a9747ca5d1c1ebd15fe0344f52ff2915e3c11b3be9be11236895e5514b085c1f8a1bd8ef9c3db0cf1095aaf442cae11d88c3af026fabd16 // PublicKey C
> 53 // OP_3
> ae // OP_CHECKMULTISIG


# 附录
## 示例1：有多重签名锁定脚本的交易
交易的hash为4373f6566e7f8095d3102485e540c948ca6932b34c8a4c38cf336cddc7be44f7，[网页展示](https://live.blockcypher.com/btc/tx/4373f6566e7f8095d3102485e540c948ca6932b34c8a4c38cf336cddc7be44f7)，[api JSON数据](https://api.blockcypher.com/v1/btc/main/txs/4373f6566e7f8095d3102485e540c948ca6932b34c8a4c38cf336cddc7be44f7?limit=50&includeHex=true)

网页截图：
![tx4373](https://user-images.githubusercontent.com/7078104/40409318-10e9fd54-5e9d-11e8-8393-7167be1e4328.png)

JSON数据：
```json
{
  "block_hash": "00000000000000000176b5e7c2b2d51308b34dda208df6f2459edbba05ec1b75",
  "block_height": 423147,
  "block_index": 1027,
  "hash": "4373f6566e7f8095d3102485e540c948ca6932b34c8a4c38cf336cddc7be44f7",
  "hex": "01000000010b15b9b578e600fdd71d07efaafeaaab10250f903374922bfe1e0f5389f5bd87010000006a4730440220008f0c0678854d2649448380adb02a7438ba8dfccfe0a85cd0bd353e08d068a4022075e6254f16d7943657127ebb6655dbd3d4fa30395b46d7a57f36ef59617b56b20121026c40b52e1bb5f301925adb124b1573b4297c234dd2c601bfaef46d40bceca70cffffffff02d8469800000000001976a914921a4c141746bbd7beb8e81b05ba93d84b076a0088ac001200000000000017a9144bb8b35e3c41be76d8c0c16a3a5a398a7688e4018700000000",
  "addresses": [
    "1EKXAAiJDntbEK3WSVW3vTcwYJ5ciJ5kSL",
    "38bPsA6ZXfRuxFD7efVXTkQd69422uzD4B"
  ],
  "total": 9984216,
  "fees": 784,
  "size": 223,
  "preference": "low",
  "relayed_by": "124.205.119.164",
  "confirmed": "2016-08-01T11:09:18Z",
  "received": "2016-08-01T06:36:38.935Z",
  "ver": 1,
  "double_spend": false,
  "vin_sz": 1,
  "vout_sz": 2,
  "confirmations": 100786,
  "confidence": 1,
  "inputs": [
    {
      "prev_hash": "87bdf589530f1efe2b927433900f2510abaafeaaef071dd7fd00e678b5b9150b",
      "output_index": 1,
      "script": "4730440220008f0c0678854d2649448380adb02a7438ba8dfccfe0a85cd0bd353e08d068a4022075e6254f16d7943657127ebb6655dbd3d4fa30395b46d7a57f36ef59617b56b20121026c40b52e1bb5f301925adb124b1573b4297c234dd2c601bfaef46d40bceca70c",
      "output_value": 9985000,
      "sequence": 4294967295,
      "addresses": [
        "1EKXAAiJDntbEK3WSVW3vTcwYJ5ciJ5kSL"
      ],
      "script_type": "pay-to-pubkey-hash",
      "age": 422655
    }
  ],
  "outputs": [
    {
      "value": 9979608,
      "script": "76a914921a4c141746bbd7beb8e81b05ba93d84b076a0088ac",
      "spent_by": "50ca192a04c92030bb08d2f67e1ec4618ebb9c8131661fc9d6efbed2966513ba",
      "addresses": [
        "1EKXAAiJDntbEK3WSVW3vTcwYJ5ciJ5kSL"
      ],
      "script_type": "pay-to-pubkey-hash"
    },
    {
      "value": 4608,
      "script": "a9144bb8b35e3c41be76d8c0c16a3a5a398a7688e40187",
      "spent_by": "ac89b280cc21854b82b4cc111a0e6c0d10315117b6001e3f4f3af3d2f7b2fd53",
      "addresses": [
        "38bPsA6ZXfRuxFD7efVXTkQd69422uzD4B"
      ],
      "script_type": "pay-to-script-hash"
    }
  ]
}
```

交易数据解析：

> 01000000 **// Version**
> 01 **// 交易输入个数**
> 0b15b9b578e600fdd71d07efaafeaaab10250f903374922bfe1e0f5389f5bd87 **// UTXO**
> 01000000 **// UTXO index**
> 6a **// 解锁脚本长度**
> 4730440220008f0c0678854d2649448380adb02a7438ba8dfccfe0a85cd0bd353e08d068a4022075e6254f16d7943657127ebb6655dbd3d4fa30395b46d7a57f36ef59617b56b20121026c40b52e1bb5f301925adb124b1573b4297c234dd2c601bfaef46d40bceca70c **// 解锁脚本**
> ffffffff **// sequence,序列号**
> 02 **// 交易输出个数**
> d846980000000000 **// 金额**
> 19 **// 锁定脚本长度**
> 76a914921a4c141746bbd7beb8e81b05ba93d84b076a0088ac **// 锁定脚本1**
> 0012000000000000 **// 金额**
> 17 **// 锁定脚本长度**
> a9144bb8b35e3c41be76d8c0c16a3a5a398a7688e40187 **// 锁定脚本2**
> 00000000 **// Time Lock**

## 示例2：有多重签名解锁脚本的交易
交易的hash为ac89b280cc21854b82b4cc111a0e6c0d10315117b6001e3f4f3af3d2f7b2fd53，[网页展示](https://live.blockcypher.com/btc/tx/ac89b280cc21854b82b4cc111a0e6c0d10315117b6001e3f4f3af3d2f7b2fd53)，[api JSON数据](https://api.blockcypher.com/v1/btc/main/txs/ac89b280cc21854b82b4cc111a0e6c0d10315117b6001e3f4f3af3d2f7b2fd53?limit=50&includeHex=true)

网页截图：
![txac89](https://user-images.githubusercontent.com/7078104/40409227-c176f524-5e9c-11e8-8000-a9cc82712300.png)

JSON数据：
```json
{
  "block_hash": "0000000000000000011edeab34b5145125efa596fbc2e6a88825acd9570aa4d8",
  "block_height": 423431,
  "block_index": 927,
  "hash": "ac89b280cc21854b82b4cc111a0e6c0d10315117b6001e3f4f3af3d2f7b2fd53",
  "hex": "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",
  "addresses": [
    "1EKXAAiJDntbEK3WSVW3vTcwYJ5ciJ5kSL",
    "38bPsA6ZXfRuxFD7efVXTkQd69422uzD4B"
  ],
  "total": 2304,
  "fees": 2304,
  "size": 437,
  "preference": "low",
  "relayed_by": "124.205.119.164",
  "confirmed": "2016-08-03T06:18:06Z",
  "received": "2016-08-03T03:26:33.685Z",
  "ver": 1,
  "double_spend": false,
  "vin_sz": 1,
  "vout_sz": 1,
  "confirmations": 100499,
  "confidence": 1,
  "inputs": [
    {
      "prev_hash": "4373f6566e7f8095d3102485e540c948ca6932b34c8a4c38cf336cddc7be44f7",
      "output_index": 1,
      "script": "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",
      "output_value": 4608,
      "sequence": 4294967295,
      "addresses": [
        "38bPsA6ZXfRuxFD7efVXTkQd69422uzD4B"
      ],
      "script_type": "pay-to-script-hash",
      "age": 423147
    }
  ],
  "outputs": [
    {
      "value": 2304,
      "script": "76a914921a4c141746bbd7beb8e81b05ba93d84b076a0088ac",
      "addresses": [
        "1EKXAAiJDntbEK3WSVW3vTcwYJ5ciJ5kSL"
      ],
      "script_type": "pay-to-pubkey-hash"
    }
  ]
}
```

交易数据解析：

> 01000000 **// Version，4字节**
> 01 **// 交易输入个数，1字节**
> f744bec7dd6c33cf384c8a4cb33269ca48c940e5852410d395807f6e56f67343 **// UTXO(Unspent Transaction Output)，32字节**
> 01000000 **// UTXO的index，4字节**
> fd5e01 **// 解锁脚本长度，VarInt，变长**
> 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 **// 解锁脚本，变长**
> ffffffff **// 交易序列号，4字节**
> 01 **// 交易输出个数，1字节**
> 0009000000000000 **// 输出金额，8字节**
> 19 **// 锁定脚本长度，VarInt，变长**
> 76a914921a4c141746bbd7beb8e81b05ba93d84b076a0088ac **// 锁定脚本，变长**
> 00000000 **// Time Lock，4字节**

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比特币中P2SH(pay-to-script-hash)多重签名的锁定脚本和解锁脚本 #17

P2SH(pay-to-script-hash)多重签名的脚本

为什么解锁脚本前面有一个空的签名OP_0？

脚本参数解释

脚本中的常量值

PUSHDATA

PublicKey

Signature的格式

示例

锁定脚本的例子解析

赎回脚本怎么得来

解锁脚本的例子解析

附录

示例1：有多重签名锁定脚本的交易

示例2：有多重签名解锁脚本的交易

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比特币中P2SH(pay-to-script-hash)多重签名的锁定脚本和解锁脚本 #17

Description

P2SH(pay-to-script-hash)多重签名的脚本

为什么解锁脚本前面有一个空的签名OP_0？

脚本参数解释

脚本中的常量值

PUSHDATA

PublicKey

Signature的格式

示例

锁定脚本的例子解析

赎回脚本怎么得来

解锁脚本的例子解析

附录

示例1：有多重签名锁定脚本的交易

示例2：有多重签名解锁脚本的交易

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