Add CKey::SignSchnorr function for BIP 340/341 signing

1 files changed, 12 insertions, 0 deletions

diff --git a/src/key.h b/src/key.h
index 3ee49a778b..d47e54800c 100644
--- a/src/key.h
+++ b/src/key.h
@@ -128,6 +128,18 @@ public:
      */
     bool SignCompact(const uint256& hash, std::vector<unsigned char>& vchSig) const;
 
+    /**
+     * Create a BIP-340 Schnorr signature, for the xonly-pubkey corresponding to *this,
+     * 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)
+     */
+    bool SignSchnorr(const uint256& hash, Span<unsigned char> sig, const uint256* merkle_root = nullptr, const uint256* aux = nullptr) const;
+
     //! Derive BIP32 child key.
     bool Derive(CKey& keyChild, ChainCode &ccChild, unsigned int nChild, const ChainCode& cc) const;