如何使用 OP_CODESEPARATOR 計算 P2WSH 簽名？

我讀了bip143，但不明白如何計算p2wsh的scriptCode。

bip143 告訴我們：

A new transaction digest algorithm is defined, but only applicable to sigops in version 0 witness program
Double SHA256 of the serialization of:
 1. nVersion of the transaction (4-byte little endian)
 2. hashPrevouts (32-byte hash)
 3. hashSequence (32-byte hash)
 4. outpoint (32-byte hash + 4-byte little endian) 
 5. scriptCode of the input (serialized as scripts inside CTxOuts)
 6. value of the output spent by this input (8-byte little endian)
 7. nSequence of the input (4-byte little endian)
 8. hashOutputs (32-byte hash)
 9. nLocktime of the transaction (4-byte little endian)
 10. sighash type of the signature (4-byte little endian)


The item 5:

For P2WPKH witness program, the scriptCode is 0x1976a914{20-byte-pubkey-hash}88ac.
For P2WSH witness program,
if the witnessScript does not contain any OP_CODESEPARATOR, the scriptCode is the witnessScript serialized as scripts inside CTxOut.
if the witnessScript contains any OP_CODESEPARATOR, the scriptCode is the witnessScript but removing everything up to and including the last executed OP_CODESEPARATOR before the signature checking opcode being executed, serialized as scripts inside CTxOut. (The exact semantics is demonstrated in the examples below)

我不知道如何找出“正在執行簽名檢查操作碼”。然後我在bip143中閱讀了範例“Native P2WSH”，我更加困惑。

這是“Native P2WSH”的第一個範例：

The following is an unsigned transaction: 0100000002fe3dc9208094f3ffd12645477b3dc56f60ec4fa8e6f5d67c565d1c6b9216b36e0000000000ffffffff0815cf020f013ed6cf91d29f4202e8a58726b1ac6c79da47c23d1bee0a6925f80000000000ffffffff0100f2052a010000001976a914a30741f8145e5acadf23f751864167f32e0963f788ac00000000
 
   nVersion:  01000000
   txin:      02 fe3dc9208094f3ffd12645477b3dc56f60ec4fa8e6f5d67c565d1c6b9216b36e 00000000 00 ffffffff
                 0815cf020f013ed6cf91d29f4202e8a58726b1ac6c79da47c23d1bee0a6925f8 00000000 00 ffffffff
   txout:     01 00f2052a01000000 1976a914a30741f8145e5acadf23f751864167f32e0963f788ac
   nLockTime: 00000000
 
 The first input comes from an ordinary P2PK:
   scriptPubKey: 21036d5c20fa14fb2f635474c1dc4ef5909d4568e5569b79fc94d3448486e14685f8ac value: 1.5625
   private key:  b8f28a772fccbf9b4f58a4f027e07dc2e35e7cd80529975e292ea34f84c4580c
   signature:    304402200af4e47c9b9629dbecc21f73af989bdaa911f7e6f6c2e9394588a3aa68f81e9902204f3fcf6ade7e5abb1295b6774c8e0abd94ae62217367096bc02ee5e435b67da201 (SIGHASH_ALL)
 
 The second input comes from a native P2WSH witness program:
   scriptPubKey : 00205d1b56b63d714eebe542309525f484b7e9d6f686b3781b6f61ef925d66d6f6a0, value: 49
   witnessScript: 21026dccc749adc2a9d0d89497ac511f760f45c47dc5ed9cf352a58ac706453880aeadab210255a9626aebf5e29c0e6538428ba0d1dcf6ca98ffdf086aa8ced5e0d0215ea465ac
                  <026dccc749adc2a9d0d89497ac511f760f45c47dc5ed9cf352a58ac706453880ae> CHECKSIGVERIFY CODESEPARATOR <0255a9626aebf5e29c0e6538428ba0d1dcf6ca98ffdf086aa8ced5e0d0215ea465> CHECKSIG
 
 To sign it with a nHashType of 3 (SIGHASH_SINGLE):
 
 hashPrevouts:
   dSHA256(fe3dc9208094f3ffd12645477b3dc56f60ec4fa8e6f5d67c565d1c6b9216b36e000000000815cf020f013ed6cf91d29f4202e8a58726b1ac6c79da47c23d1bee0a6925f800000000)
 = ef546acf4a020de3898d1b8956176bb507e6211b5ed3619cd08b6ea7e2a09d41
 
   nVersion:     01000000
   hashPrevouts: ef546acf4a020de3898d1b8956176bb507e6211b5ed3619cd08b6ea7e2a09d41
   hashSequence: 0000000000000000000000000000000000000000000000000000000000000000
   outpoint:     0815cf020f013ed6cf91d29f4202e8a58726b1ac6c79da47c23d1bee0a6925f800000000
   scriptCode:   (see below)
   amount:       0011102401000000
   nSequence:    ffffffff
   hashOutputs:  0000000000000000000000000000000000000000000000000000000000000000 (this is the second input but there is only one output)
   nLockTime:    00000000
   nHashType:    03000000
 
 scriptCode:  4721026dccc749adc2a9d0d89497ac511f760f45c47dc5ed9cf352a58ac706453880aeadab210255a9626aebf5e29c0e6538428ba0d1dcf6ca98ffdf086aa8ced5e0d0215ea465ac
                                                                                      ^^
              (please note that the not-yet-executed OP_CODESEPARATOR is not removed from the scriptCode)
 preimage:    01000000ef546acf4a020de3898d1b8956176bb507e6211b5ed3619cd08b6ea7e2a09d4100000000000000000000000000000000000000000000000000000000000000000815cf020f013ed6cf91d29f4202e8a58726b1ac6c79da47c23d1bee0a6925f8000000004721026dccc749adc2a9d0d89497ac511f760f45c47dc5ed9cf352a58ac706453880aeadab210255a9626aebf5e29c0e6538428ba0d1dcf6ca98ffdf086aa8ced5e0d0215ea465ac0011102401000000ffffffff00000000000000000000000000000000000000000000000000000000000000000000000003000000
 sigHash:     82dde6e4f1e94d02c2b7ad03d2115d691f48d064e9d52f58194a6637e4194391
 public key:  026dccc749adc2a9d0d89497ac511f760f45c47dc5ed9cf352a58ac706453880ae
 private key: 8e02b539b1500aa7c81cf3fed177448a546f19d2be416c0c61ff28e577d8d0cd
 signature:   3044022027dc95ad6b740fe5129e7e62a75dd00f291a2aeb1200b84b09d9e3789406b6c002201a9ecd315dd6a0e632ab20bbb98948bc0c6fb204f2c286963bb48517a7058e2703
 
 scriptCode:  23210255a9626aebf5e29c0e6538428ba0d1dcf6ca98ffdf086aa8ced5e0d0215ea465ac
              (everything up to the last executed OP_CODESEPARATOR, including that OP_CODESEPARATOR, are removed)
 preimage:    01000000ef546acf4a020de3898d1b8956176bb507e6211b5ed3619cd08b6ea7e2a09d4100000000000000000000000000000000000000000000000000000000000000000815cf020f013ed6cf91d29f4202e8a58726b1ac6c79da47c23d1bee0a6925f80000000023210255a9626aebf5e29c0e6538428ba0d1dcf6ca98ffdf086aa8ced5e0d0215ea465ac0011102401000000ffffffff00000000000000000000000000000000000000000000000000000000000000000000000003000000
 sigHash:     fef7bd749cce710c5c052bd796df1af0d935e59cea63736268bcbe2d2134fc47
 public key:  0255a9626aebf5e29c0e6538428ba0d1dcf6ca98ffdf086aa8ced5e0d0215ea465
 private key: 86bf2ed75935a0cbef03b89d72034bb4c189d381037a5ac121a70016db8896ec
 signature:   304402200de66acf4527789bfda55fc5459e214fa6083f936b430a762c629656216805ac0220396f550692cd347171cbc1ef1f51e15282e837bb2b30860dc77c8f78bc8501e503
 
 The serialized signed transaction is: 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

01000000
0001
02
fe3dc9208094f3ffd12645477b3dc56f60ec4fa8e6f5d67c565d1c6b9216b36e 00000000
48
47304402200af4e47c9b9629dbecc21f73af989bdaa911f7e6f6c2e9394588a3aa68f81e9902204f3fcf6ade7e5abb1295b6774c8e0abd94ae62217367096bc02ee5e435b67da201
ffffffff
0815cf020f013ed6cf91d29f4202e8a58726b1ac6c79da47c23d1bee0a6925f8 0000000000
ffffffff

01
00f2052a01000000
1976a914a30741f8145e5acadf23f751864167f32e0963f788ac

0003

47304402200de66acf4527789bfda55fc5459e214fa6083f936b430a762c629656216805ac0220396f550692cd347171cbc1ef1f51e15282e837bb2b30860dc77c8f78bc8501e503
473044022027dc95ad6b740fe5129e7e62a75dd00f291a2aeb1200b84b09d9e3789406b6c002201a9ecd315dd6a0e632ab20bbb98948bc0c6fb204f2c286963bb48517a7058e2703
4721026dccc749adc2a9d0d89497ac511f760f45c47dc5ed9cf352a58ac706453880aeadab210255a9626aebf5e29c0e6538428ba0d1dcf6ca98ffdf086aa8ced5e0d0215ea465ac

所以這是我的問題：

1. 這裡的“witnessScript”就是 RedeemScript，對吧？
2. 這裡的“CODESEPARATOR”是什麼意思？
3. 為什麼要計算兩個 scriptCode（OP_CODESEPARATOR 未刪除 && OP_CODESEPARATOR 已刪除）並將它們都放入見證數據中？

是的，這裡witnessScript的 P2WSH 指的是以前稱為redeemScriptP2SH 的東西。

CODESEPARATOR是一個（有趣的 [ 1 ]）OP 程式碼，它允許自定義CHECKSIGOP 程式碼的行為。它允許將簽名的腳本程式碼分段以僅送出到其中的一部分。

BIP143稍微 改變了其對 SegWit 腳本的行為。

為什麼需要計算兩個 scriptCode（OP_CODESEPARATOR 未被刪除 && OP_CODESEPARATOR 被刪除）並將它們都放入見證數據中？

嗯，我猜你指的是這些行：

please note that the not-yet-executed OP_CODESEPARATOR is not removed from the scriptCode

這是為了說明新的行為：CODESEPARATOROP 沒有與它綁定的程式碼部分一起被刪除（以前是這樣）。

---

[ 1 ]CODESEPARATOR最初用於將 scriptPubkey 和 scriptSig 作為單個堆棧（插入中間）執行。然後在修復錯誤時被 Satoshi 刪除1 RETURN。

是的，witnessScript 只是 RedeemScript，它也是見證數據的最後一個元素。我不確定 OP_CODESEPARATOR，或者為什麼腳本首先會包含它。

引用自：https://bitcoin.stackexchange.com/questions/89454