diff --git a/10_2_Building_the_Structure_of_P2SH.md b/10_2_Building_the_Structure_of_P2SH.md index 7d74afe..28c78cf 100644 --- a/10_2_Building_the_Structure_of_P2SH.md +++ b/10_2_Building_the_Structure_of_P2SH.md @@ -106,9 +106,9 @@ Here's what the individual parts mean: * 0x52 = OP_2 * 0x21 = OP_PUSHDATA 33 bytes (hex: 0x21) -* 0x02da2f10746e9778dd57bd0276a4f84101c4e0a711f9cfd9f09cde55acbdd2d191 = the next 33 bytes (public-key hash) +* 0x02da2f10746e9778dd57bd0276a4f84101c4e0a711f9cfd9f09cde55acbdd2d191 = the next 33 bytes (public key) * 0x21 = OP_PUSHDATA 33 bytes (hex: 0x21) -* 0x02bfde48be4aa8f4bf76c570e98a8d287f9be5638412ab38dede8e78df82f33fa3 = the next 33 bytes (public-key hash) +* 0x02bfde48be4aa8f4bf76c570e98a8d287f9be5638412ab38dede8e78df82f33fa3 = the next 33 bytes (public key) * 0x52 = OP_2 * 0xae = OP_CHECKMULTISIG diff --git a/10_4_Scripting_a_Multisig.md b/10_4_Scripting_a_Multisig.md index 4aab0a1..f779e9f 100644 --- a/10_4_Scripting_a_Multisig.md +++ b/10_4_Scripting_a_Multisig.md @@ -4,17 +4,19 @@ Before we close out this intro to P2SH scripting, it's worth examining a more re ## Understand the Multisig Code -Multisig transactions are created in Bitcoin using the `OP_CHECKMULTISIG` code. `OP_CHECKMULTISIG` expects a long string of arguments that looks like this: `0 ... sigs ... ... addresses ... OP_CHECKMULTISIG`. When `OP_CHECKMULTISIG` is run, it does the following: +Multisig transactions are created in Bitcoin using the `OP_CHECKMULTISIG` code. `OP_CHECKMULTISIG` expects a long string of arguments that looks like this: `0 ... sigs ... ... public keys ... OP_CHECKMULTISIG`. When `OP_CHECKMULTISIG` is run, it does the following: 1. Pop the first value from the stack (``). -2. Pop "n" values from the stack as Bitcoin addresses (hashed public keys). +2. Pop "n" values from the stack as public keys. 3. Pop the next value from the stack (``). 4. Pop "m" values from the stack as potential signatures. 5. Pop a `0` from the stack due to a mistake in the original coding. -6. Compare the signatures to the Bitcoin adddresses. +6. Compare the signatures to the public keys. 7. Push a `True` or `False` depending on the result. -The operands of `OP_MULTISIG` are typically divided, with the `0` and the signatures coming from the unlocking script and the "m", "n", and addresses being detailed by the locking script. +The operands of `OP_MULTISIG` are typically divided, with the `0` and +the signatures coming from the unlocking script and the "m", "n", and +public keys being detailed by the locking script. The requirement for that `0` as the first operand for `OP_CHECKMULTISIG` is a consensus rule. Because the original version of `OP_CHECKMULTISIG` accidentally popped an extra item off the stack, Bitcoin must forever follow that standard, lest complex redemption scripts from that time period accidentally be broken, rendering old funds unredeemable. @@ -24,11 +26,11 @@ The requirement for that `0` as the first operand for `OP_CHECKMULTISIG` is a co As discussed in [§10.1: Understanding the Foundation of P2SH](10_1_Understanding_the_Foundation_of_P2SH.md), multisigs are one of the standard Bitcoin transaction types. A transaction can be created with a locking script that uses the raw `OP_CHECKMULTISIG` command, and it will be accepted into a block. This is the classic methodology for using multisigs in Bitcoin. -As an example, we will revisit the multisig created in [§6.1](06_1_Sending_a_Transaction_to_a_Multisig.md) one final time and build a new locking script for it using this methodology. As you may recall, that was a 2-of-2 multisig built from `$address1` and `$address2`. +As an example, we will revisit the multisig created in [§6.1](06_1_Sending_a_Transaction_to_a_Multisig.md) one final time and build a new locking script for it using this methodology. As you may recall, that was a 2-of-2 multisig built from `$pubkey1` and `$pubkey2`. -As `OP_CHECKMULTISIG` locking script requires the "m" (`2`), the addresses, and the "n" (`2`), you could write the following `scriptPubKey`: +As `OP_CHECKMULTISIG` locking script requires the "m" (`2`), the public keys, and the "n" (`2`), you could write the following `scriptPubKey`: ``` -2 $address1 $address2 2 OP_CHECKMULTISIG +2 $pubkey1 $pubkey2 2 OP_CHECKMULTISIG ``` If this looks familiar, that's because it's the multisig that you deserialized in [§10.2: Building the Structure of P2SH](10_2_Building_the_Structure_of_P2SH.md). ``` @@ -48,20 +50,20 @@ The `scriptSig` for a standard multisig address must then submit the missing ope In order to spend a multisig UTXO, you run the `scriptSig` and `scriptPubKey` as follows: ``` -Script: 0 $signature1 $signature2 2 $address1 $address2 2 OP_CHECKMULTISIG +Script: 0 $signature1 $signature2 2 $pubkey1 $pubkey2 2 OP_CHECKMULTISIG Stack: [ ] ``` First, you place all the constants on the stack: ``` Script: OP_CHECKMULTISIG -Stack: [ 0 $signature1 $signature2 2 $address1 $address2 2 ] +Stack: [ 0 $signature1 $signature2 2 $pubkey1 $pubkey2 2 ] ``` Then, the `OP_CHECKMULTISIG` begins to run. First, the "2" is popped: ``` Running: OP_CHECKMULTISIG -Stack: [ 0 $signature1 $signature2 2 $address1 $address2 ] +Stack: [ 0 $signature1 $signature2 2 $pubkey1 $pubkey2 ] ``` -Then, the "2" tells `OP_CHECKMULTISIG `to pop two addresses: +Then, the "2" tells `OP_CHECKMULTISIG `to pop two public keys: ``` Running: OP_CHECKMULTISIG Stack: [ 0 $signature1 $signature2 2 ] @@ -81,7 +83,7 @@ Then, one more item is mistakenly popped: Running: OP_CHECKMULTISIG Stack: [ ] ``` -Then, `OP_CHECKMULTISIG` completes its operation by comparing the "m" signatures to the "n" addresses: +Then, `OP_CHECKMULTISIG` completes its operation by comparing the "m" signatures to the "n" public keys: ``` Script: Stack: [ True ] @@ -105,7 +107,7 @@ P2SH multisigs are the modern methodology for creating multisigs on the Blockcha To create a P2SH multisig, follow the standard steps for creating a P2SH locking script: -1. Serialize `2 $address1 $address2 2 OP_CHECKMULTISIG`. +1. Serialize `2 $pubkey1 $pubkey2 2 OP_CHECKMULTISIG`. 1. `` = "522102da2f10746e9778dd57bd0276a4f84101c4e0a711f9cfd9f09cde55acbdd2d1912102bfde48be4aa8f4bf76c570e98a8d287f9be5638412ab38dede8e78df82f33fa352ae" 2. Save `` for future reference as the redeemScript. 1. `` = "522102da2f10746e9778dd57bd0276a4f84101c4e0a711f9cfd9f09cde55acbdd2d1912102bfde48be4aa8f4bf76c570e98a8d287f9be5638412ab38dede8e78df82f33fa352ae" @@ -133,9 +135,9 @@ To unlock the P2SH multisig, first confirm the script: Then, run the multisig script: -1. Deserialize `` to `2 $address1 $address2 2 OP_CHECKMULTISIG`. +1. Deserialize `` to `2 $pubkey1 $pubkey2 2 OP_CHECKMULTISIG`. 2. Concatenate that with the earlier operands in the unlocking script, `0 $signature1 $signature2`. -3. Validate `0 $signature1 $signature2 2 $address1 $address2 2 OP_CHECKMULTISIG`. +3. Validate `0 $signature1 $signature2 2 $pubkey1 $pubkey2 2 OP_CHECKMULTISIG`. 4. Succeed if the operands fulfill the deserialized `redeemScript`. Now you know how the multisig transaction in [§6.1](06_1_Sending_a_Transaction_to_a_Multisig.md) was actually created, how it was validated for spending, and why that `redeemScript` was so important.