implement OP_TWEAKADD

reardencode · Jul 31, 2024 · 309e045 · 309e045
1 parent 0cbdc6b
commit 309e045
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Showing 5 changed files with 30 additions and 2 deletions.
diff --git a/src/pubkey.cpp b/src/pubkey.cpp
@@ -246,12 +246,11 @@ bool XOnlyPubKey::CheckTapTweak(const XOnlyPubKey& internal, const uint256& merk
     return secp256k1_xonly_pubkey_tweak_add_check(secp256k1_context_static, m_keydata.begin(), parity, &internal_key, tweak.begin());
 }
 
-std::optional<std::pair<XOnlyPubKey, bool>> XOnlyPubKey::CreateTapTweak(const uint256* merkle_root) const
+std::optional<std::pair<XOnlyPubKey, bool>> XOnlyPubKey::TweakAdd(const uint256& tweak) const
 {
     secp256k1_xonly_pubkey base_point;
     if (!secp256k1_xonly_pubkey_parse(secp256k1_context_static, &base_point, data())) return std::nullopt;
     secp256k1_pubkey out;
-    uint256 tweak = ComputeTapTweakHash(merkle_root);
     if (!secp256k1_xonly_pubkey_tweak_add(secp256k1_context_static, &out, &base_point, tweak.data())) return std::nullopt;
     int parity = -1;
     std::pair<XOnlyPubKey, bool> ret;
@@ -263,6 +262,11 @@ std::optional<std::pair<XOnlyPubKey, bool>> XOnlyPubKey::CreateTapTweak(const ui
     return ret;
 }
 
+std::optional<std::pair<XOnlyPubKey, bool>> XOnlyPubKey::CreateTapTweak(const uint256* merkle_root) const
+{
+    return TweakAdd(ComputeTapTweakHash(merkle_root));
+}
+
 
 bool CPubKey::Verify(const uint256 &hash, const std::vector<unsigned char>& vchSig) const {
     if (!IsValid())

diff --git a/src/pubkey.h b/src/pubkey.h
@@ -274,6 +274,9 @@ class XOnlyPubKey
      *  Merkle root, and parity. */
     bool CheckTapTweak(const XOnlyPubKey& internal, const uint256& merkle_root, bool parity) const;
 
+    /** Add the specified tweak to this xonly pubkey. */
+    std::optional<std::pair<XOnlyPubKey, bool>> TweakAdd(const uint256& tweak) const;
+
     /** Construct a Taproot tweaked output point with this point as internal key. */
     std::optional<std::pair<XOnlyPubKey, bool>> CreateTapTweak(const uint256* merkle_root) const;
 

diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
@@ -1213,6 +1213,25 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
                 }
                 break;
 
+                case OP_TWEAKADD:
+                {
+                    // pubkey tweak -- tweaked_pubkey parity(0|1)
+                    if (stack.size() < 2)
+                        return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
+
+                    const valtype& pubkey = stacktop(-2);
+                    const valtype& tweak = stacktop(-1);
+                    const XOnlyPubKey p{Span{pubkey}};
+                    const std::optional<std::pair<XOnlyPubKey, bool>> ret = p.TweakAdd(uint256(tweak));
+                    if (!ret.has_value())
+                        return set_error(serror, SCRIPT_ERR_UNKNOWN_ERROR);
+                    popstack(stack);
+                    popstack(stack);
+                    stack.emplace_back(ret.value().first.begin(), ret.value().first.end());
+                    stack.push_back(ret.value().second ? vchTrue : vchFalse);
+                }
+                break;
+
                 default:
                     return set_error(serror, SCRIPT_ERR_BAD_OPCODE);
             }

diff --git a/src/script/script.cpp b/src/script/script.cpp
@@ -148,6 +148,7 @@ std::string GetOpName(opcodetype opcode)
 
     // Opcode added by BIP 342 (Tapscript)
     case OP_CHECKSIGADD            : return "OP_CHECKSIGADD";
+    case OP_TWEAKADD               : return "OP_TWEAKADD";
 
     case OP_INVALIDOPCODE          : return "OP_INVALIDOPCODE";
 

diff --git a/src/script/script.h b/src/script/script.h
@@ -207,6 +207,7 @@ enum opcodetype
 
     // Opcode added by BIP 342 (Tapscript)
     OP_CHECKSIGADD = 0xba,
+    OP_TWEAKADD = 0xcd,
 
     OP_INVALIDOPCODE = 0xff,
 };