Add OP_INTERNALKEY for Tapscript

Testing is minimal, but so is the code.
reardencode · Jan 8, 2024 · eb3cba0 · eb3cba0
1 parent 0327dd3
commit eb3cba0
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Showing 7 changed files with 36 additions and 2 deletions.
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
@@ -1248,6 +1248,17 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
                 }
                 break;
 
+                case OP_INTERNALKEY: {
+                    // OP_INTERNALKEY is only available in Tapscript
+                    if (sigversion == SigVersion::BASE || sigversion == SigVersion::WITNESS_V0) return set_error(serror, SCRIPT_ERR_BAD_OPCODE);
+                    if (flags & SCRIPT_VERIFY_DISCOURAGE_LNHANCE) {
+                        return set_error(serror, SCRIPT_ERR_DISCOURAGE_OP_SUCCESS);
+                    }
+
+                    stack.emplace_back(execdata.m_internal_key.begin(), execdata.m_internal_key.end());
+                    break;
+                }
+
                 default:
                     return set_error(serror, SCRIPT_ERR_BAD_OPCODE);
             }
@@ -1922,6 +1933,9 @@ static bool ExecuteWitnessScript(const Span<const valtype>& stack_span, const CS
                 // Note how this condition would not be reached if an unknown OP_SUCCESSx was found
                 return set_error(serror, SCRIPT_ERR_BAD_OPCODE);
             }
+            if ((flags & SCRIPT_VERIFY_LNHANCE) && opcode == OP_INTERNALKEY) {
+                continue;
+            }
             // New opcodes will be listed here. May use a different sigversion to modify existing opcodes.
             if (IsOpSuccess(opcode)) {
                 if (flags & SCRIPT_VERIFY_DISCOURAGE_OP_SUCCESS) {
@@ -1982,7 +1996,6 @@ uint256 ComputeTaprootMerkleRoot(Span<const unsigned char> control, const uint25
 
 static bool VerifyTaprootCommitment(const std::vector<unsigned char>& control, const std::vector<unsigned char>& program, const uint256& tapleaf_hash)
 {
-    assert(control.size() >= TAPROOT_CONTROL_BASE_SIZE);
     assert(program.size() >= uint256::size());
     //! The internal pubkey (x-only, so no Y coordinate parity).
     const XOnlyPubKey p{Span{control}.subspan(1, TAPROOT_CONTROL_BASE_SIZE - 1)};
@@ -2050,6 +2063,9 @@ static bool VerifyWitnessProgram(const CScriptWitness& witness, int witversion,
             if (control.size() < TAPROOT_CONTROL_BASE_SIZE || control.size() > TAPROOT_CONTROL_MAX_SIZE || ((control.size() - TAPROOT_CONTROL_BASE_SIZE) % TAPROOT_CONTROL_NODE_SIZE) != 0) {
                 return set_error(serror, SCRIPT_ERR_TAPROOT_WRONG_CONTROL_SIZE);
             }
+            assert(control.size() >= TAPROOT_CONTROL_BASE_SIZE);
+            execdata.m_internal_key = uint256{Span{control}.subspan(1, TAPROOT_CONTROL_BASE_SIZE - 1)};
+            execdata.m_internal_key_init = true;
             execdata.m_tapleaf_hash = ComputeTapleafHash(control[0] & TAPROOT_LEAF_MASK, script);
             if (!VerifyTaprootCommitment(control, program, execdata.m_tapleaf_hash)) {
                 return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH);

diff --git a/src/script/interpreter.h b/src/script/interpreter.h
@@ -227,6 +227,10 @@ struct ScriptExecutionData
     //! The tapleaf hash.
     uint256 m_tapleaf_hash;
 
+    //! Whether m_internal_key is initialized.
+    bool m_internal_key_init = false;
+    uint256 m_internal_key;
+
     //! Whether m_codeseparator_pos is initialized.
     bool m_codeseparator_pos_init = false;
     //! Opcode position of the last executed OP_CODESEPARATOR (or 0xFFFFFFFF if none executed).

diff --git a/src/script/script.cpp b/src/script/script.cpp
@@ -146,6 +146,8 @@ std::string GetOpName(opcodetype opcode)
     // Opcode added by BIP 342 (Tapscript)
     case OP_CHECKSIGADD            : return "OP_CHECKSIGADD";
 
+    case OP_INTERNALKEY            : return "OP_INTERNALKEY";
+
     case OP_INVALIDOPCODE          : return "OP_INVALIDOPCODE";
 
     default:

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_INTERNALKEY = 0xbb,
 
     OP_INVALIDOPCODE = 0xff,
 };

diff --git a/src/test/data/tx_valid.json b/src/test/data/tx_valid.json
@@ -668,5 +668,13 @@
 "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",
  "CLEANSTACK,DISCOURAGE_LNHANCE"],
 
+ ["Test OP_INTERNALKEY"],
+ [[["e2f2baee9c59389b34e39742ce05debf64aaa7a00fbdab88614f4d3c133186d5",
+  0,
+  "1 0x20 0x15887b8f5cc1e8d98ffa7af368d0159cfbee6de780d012f7379ba12d363900e3",
+  155000]],
+"02000000000101d58631133c4d4f6188abbd0fa0a7aa64bfde05ce4297e3349b38599ceebaf2e20000000000ffffffff01f0490200000000002251202ca3bc76489a54904ad2507005789afc1e6b362b451be89f69de39ddf9ba8abf0223bb2050929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac08721c150929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac000000000",
+ "DISCOURAGE_LNHANCE"],
+
 ["Make diffs cleaner by leaving a comment here without comma at the end"]
 ]
diff --git a/src/test/transaction_tests.cpp b/src/test/transaction_tests.cpp
@@ -151,6 +151,9 @@ bool CheckTxScripts(const CTransaction& tx, const std::map<COutPoint, CScript>&
 
 unsigned int TrimFlags(unsigned int flags)
 {
+    // !LNHANCE requires !DISCOURGE_OP_SUCCESS
+    if (!(flags & SCRIPT_VERIFY_LNHANCE)) flags &= ~(unsigned int)SCRIPT_VERIFY_DISCOURAGE_OP_SUCCESS;
+
     // WITNESS requires P2SH
     if (!(flags & SCRIPT_VERIFY_P2SH)) flags &= ~(unsigned int)SCRIPT_VERIFY_WITNESS;
 

diff --git a/test/functional/test_framework/script.py b/test/functional/test_framework/script.py
@@ -925,4 +925,4 @@ def taproot_construct(pubkey, scripts=None, treat_internal_as_infinity=False):
     return TaprootInfo(CScript([OP_1, tweaked]), pubkey, negated + 0, tweak, leaves, h, tweaked)
 
 def is_op_success(o):
-    return o == 0x50 or o == 0x62 or o == 0x89 or o == 0x8a or o == 0x8d or o == 0x8e or (o >= 0x7e and o <= 0x81) or (o >= 0x83 and o <= 0x86) or (o >= 0x95 and o <= 0x99) or (o >= 0xbb and o <= 0xfe)
+    return o == 0x50 or o == 0x62 or o == 0x89 or o == 0x8a or o == 0x8d or o == 0x8e or (o >= 0x7e and o <= 0x81) or (o >= 0x83 and o <= 0x86) or (o >= 0x95 and o <= 0x99) or (o >= 0xbc and o <= 0xfe)