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443: fix some errors in the python pseudocode and a wrong reference.

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Salvatore Ingala 2025-06-22 19:36:57 +02:00
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bip-0443.mediawiki
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@ -100,7 +100,7 @@ exhaustive, as there are many more possible combinations.
in the same transaction, or multiple times with the ''deduct'' logic. This prevents duplicate or inconsistent counting
of the same amounts.
'''Remark:''' it is allowed to check for multiple inputs to check the same output with the ''default'' logic. This
'''Remark:''' it is allowed for multiple inputs to check the same output with the ''default'' logic. This
allows multiple inputs to aggregate (in full or in part) their amounts to the same output.
-----
@ -176,7 +176,7 @@ would always be hard-coded via a push in the script, the risk of mistakes seems
The following values of the other parameters have special meanings:
* If the <code><taptree></code> is -1, it is replaced with the Merkle root of the current input's tapscript tree. If the taptree is the empty buffer, then the taptweak is skipped.
* If the <code><pk></code> is 0, it is replaced with the NUMS x-only pubkey <code>0x50929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac0</code> defined in [[bip-0340.mediawiki|BIP-340]]. If the <code><pk></code> is -1, it is replaced with the taproot internal key of the current input.
* If the <code><pk></code> is 0, it is replaced with the NUMS x-only pubkey <code>0x50929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac0</code> defined in [[bip-0341.mediawiki|BIP-341]]. If the <code><pk></code> is -1, it is replaced with the taproot internal key of the current input.
* If the <code><index></code> is -1, it is replaced with the index of the current input.
* If the <code><data></code> is the empty buffer, then there is no data tweak for the input/output being checked.
@ -190,13 +190,17 @@ The specification is divided into three parts:
* the input initialization;
* the opcode evaluation.
The following helper function is a version of <code>taproot_tweak_pubkey</code>, except that a raw 32-byte data is used
as the tweak.
The following helper function is a variant of <code>taproot_tweak_pubkey</code> from [[bip-0341.mediawiki|BIP341]],
except that a regular SHA256-hash is used instead of a tagged hash, and the pubkey is returned unchanged if the length
of <code>data</code> is 0.
<source lang="python">
def tweak_embed_data(pubkey, data):
assert len(pubkey) == 32
if len(data) == 0:
return None, pubkey
data_tweak = sha256(pubkey + data)
t = int_from_bytes(data_tweak)
@ -209,7 +213,7 @@ def tweak_embed_data(pubkey, data):
return 0 if has_even_y(Q) else 1, bytes_from_int(x(Q))
</source>
The <code>taproot_tweak_pubkey</code> from [[bip-0341.mediawiki|BIP-341]] is also used as a helper function.
The <code>taproot_tweak_pubkey</code> function is also used as a helper in the pseudocode below.
The following notations are used in the pseudocode below:
* <code>n_inputs</code> and <code>n_outputs</code> are the number of inputs and outputs of the transaction, respectively;