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author | Pieter Wuille <pieter@wuille.net> | 2021-06-17 16:54:56 -0700 |
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committer | Pieter Wuille <pieter@wuille.net> | 2021-08-20 14:29:23 -0400 |
commit | addb9b5a71ff96bdb1a4c15bc9345de0d7f2c98c (patch) | |
tree | 7d3753ee845ed37f88755bec6c0ce8a8784b00c9 /src | |
parent | 4fc15d15667d9d9c4fb5515ce73c05b4596298ec (diff) | |
download | bitcoin-addb9b5a71ff96bdb1a4c15bc9345de0d7f2c98c.tar.xz |
Improve comments in taproot signing logic
Diffstat (limited to 'src')
-rw-r--r-- | src/key.h | 13 | ||||
-rw-r--r-- | src/script/interpreter.h | 7 | ||||
-rw-r--r-- | src/script/sign.cpp | 2 | ||||
-rw-r--r-- | src/script/standard.h | 9 |
4 files changed, 23 insertions, 8 deletions
@@ -133,10 +133,15 @@ public: * optionally tweaked by *merkle_root. Additional nonce entropy can be provided through * aux. * - * When merkle_root is not nullptr, this results in a signature with a modified key as - * specified in BIP341: - * - If merkle_root->IsNull(): key + H_TapTweak(pubkey)*G - * - Otherwise: key + H_TapTweak(pubkey || *merkle_root) + * merkle_root is used to optionally perform tweaking of the private key, as specified + * in BIP341: + * - If merkle_root == nullptr: no tweaking is done, sign with key directly (this is + * used for signatures in BIP342 script). + * - If merkle_root->IsNull(): sign with key + H_TapTweak(pubkey) (this is used for + * key path spending when no scripts are present). + * - Otherwise: sign with key + H_TapTweak(pubkey || *merkle_root) + * (this is used for key path spending, with specific + * Merkle root of the script tree). */ bool SignSchnorr(const uint256& hash, Span<unsigned char> sig, const uint256* merkle_root = nullptr, const uint256* aux = nullptr) const; diff --git a/src/script/interpreter.h b/src/script/interpreter.h index 93136a0b79..ab49e84577 100644 --- a/src/script/interpreter.h +++ b/src/script/interpreter.h @@ -170,6 +170,13 @@ struct PrecomputedTransactionData PrecomputedTransactionData() = default; + /** Initialize this PrecomputedTransactionData with transaction data. + * + * @param[in] tx The transaction for which data is being precomputed. + * @param[in] spent_outputs The CTxOuts being spent, one for each tx.vin, in order. + * @param[in] force Whether to precompute data for all optional features, + * regardless of what is in the inputs (used at signing + * time, when the inputs aren't filled in yet). */ template <class T> void Init(const T& tx, std::vector<CTxOut>&& spent_outputs, bool force = false); diff --git a/src/script/sign.cpp b/src/script/sign.cpp index 2faf7e5048..2a1c99e387 100644 --- a/src/script/sign.cpp +++ b/src/script/sign.cpp @@ -61,7 +61,7 @@ bool MutableTransactionSignatureCreator::CreateSchnorrSig(const SigningProvider& CKey key; { - // For now, use the old full pubkey-based key derivation logic. As it indexed by + // For now, use the old full pubkey-based key derivation logic. As it is indexed by // Hash160(full pubkey), we need to try both a version prefixed with 0x02, and one // with 0x03. unsigned char b[33] = {0x02}; diff --git a/src/script/standard.h b/src/script/standard.h index ac4e2f3276..78492733db 100644 --- a/src/script/standard.h +++ b/src/script/standard.h @@ -227,8 +227,11 @@ struct TaprootSpendData /** The Merkle root of the script tree (0 if no scripts). */ uint256 merkle_root; /** Map from (script, leaf_version) to (sets of) control blocks. - * The control blocks are sorted by size, so that the signing logic can - * easily prefer the cheapest one. */ + * More than one control block for a given script is only possible if it + * appears in multiple branches of the tree. We keep them all so that + * inference can reconstruct the full tree. Within each set, the control + * blocks are sorted by size, so that the signing logic can easily + * prefer the cheapest one. */ std::map<std::pair<CScript, int>, std::set<std::vector<unsigned char>, ShortestVectorFirstComparator>> scripts; /** Merge other TaprootSpendData (for the same scriptPubKey) into this. */ void Merge(TaprootSpendData other); @@ -252,7 +255,7 @@ private: /** Merkle hash of this node. */ uint256 hash; /** Tracked leaves underneath this node (either from the node itself, or its children). - * The merkle_branch field for each is the partners to get to *this* node. */ + * The merkle_branch field of each is the partners to get to *this* node. */ std::vector<LeafInfo> leaves; }; /** Whether the builder is in a valid state so far. */ |