extract evalChecksig method and fix checkPayToContract in both EcAdap…

…ter implementations
Bit-Wasp · Nov 10, 2019 · b08c28e · b08c28e
1 parent 5ee69f0
commit b08c28e
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Showing 11 changed files with 84 additions and 20 deletions.
diff --git a/composer.json b/composer.json
@@ -18,7 +18,7 @@
     "files": [
       "src/Script/functions.php",
       "src/Script/sighash_functions.php",
-      "src/Script/script_constants.php"
+      "src/Script/Interpreter/interpreter_constants.php"
     ]
   },
   "autoload-dev": {

diff --git a/src/Crypto/EcAdapter/Impl/PhpEcc/Key/XOnlyPublicKey.php b/src/Crypto/EcAdapter/Impl/PhpEcc/Key/XOnlyPublicKey.php
@@ -61,9 +61,10 @@ public function tweakAdd(BufferInterface $tweak32): XOnlyPublicKeyInterface
     public function checkPayToContract(XOnlyPublicKeyInterface $base, BufferInterface $hash, bool $hasSquareY): bool
     {
         $pkExpected = $base->tweakAdd($hash);
+        $xEquals = gmp_cmp($pkExpected->getPoint()->getX(), $this->point->getX()) === 0;
+        $squareEquals = $pkExpected->hasSquareY() === !$hasSquareY;
         /** @var XOnlyPublicKey $pkExpected */
-        return gmp_cmp($pkExpected->getPoint()->getX(), $this->point->getX()) === 0 &&
-            $pkExpected->hasSquareY() === $hasSquareY;
+        return $xEquals && $squareEquals;
     }
 
     public function getBuffer(): BufferInterface

diff --git a/src/Crypto/EcAdapter/Impl/Secp256k1/Key/XOnlyPublicKey.php b/src/Crypto/EcAdapter/Impl/Secp256k1/Key/XOnlyPublicKey.php
@@ -96,7 +96,10 @@ public function tweakAdd(BufferInterface $tweak32): XOnlyPublicKeyInterface
 
     private function doCheckPayToContract(XOnlyPublicKey $base, BufferInterface $hash, bool $negated): bool
     {
-        return secp256k1_xonly_pubkey_tweak_verify($this->context, $this->xonlyKey, (int) !$negated, $base->xonlyKey, $hash->getBinary());
+        if (1 !== secp256k1_xonly_pubkey_tweak_verify($this->context, $this->xonlyKey, (int) !$negated, $base->xonlyKey, $hash->getBinary())) {
+            return false;
+        }
+        return true;
     }
 
     public function checkPayToContract(XOnlyPublicKeyInterface $base, BufferInterface $hash, bool $hasSquareY): bool

diff --git a/src/Crypto/EcAdapter/Impl/Secp256k1/Serializer/Signature/SchnorrSignatureSerializer.php b/src/Crypto/EcAdapter/Impl/Secp256k1/Serializer/Signature/SchnorrSignatureSerializer.php
@@ -64,6 +64,6 @@ public function parse(BufferInterface $sig): SchnorrSignatureInterface
             throw new \RuntimeException('Unable to parse compact signature');
         }
         /** @var resource $sig_t */
-        return new SchnorrSignature($this->ecAdapter, $sig_t);
+        return new SchnorrSignature($this->ecAdapter->getContext(), $sig_t);
     }
 }
diff --git a/src/Script/Interpreter/CheckerBase.php b/src/Script/Interpreter/CheckerBase.php
@@ -14,7 +14,7 @@
 use BitWasp\Bitcoin\Exceptions\ScriptRuntimeException;
 use BitWasp\Bitcoin\Exceptions\SignatureNotCanonical;
 use BitWasp\Bitcoin\Locktime;
-use BitWasp\Bitcoin\Script\ExecutionContext;
+use BitWasp\Bitcoin\Script\Interpreter\ExecutionContext;
 use BitWasp\Bitcoin\Script\PrecomputedData;
 use BitWasp\Bitcoin\Script\ScriptInterface;
 use BitWasp\Bitcoin\Serializer\Signature\TransactionSignatureSerializer;

diff --git a/src/Script/ExecutionContext.php → src/Script/Interpreter/ExecutionContext.php b/src/Script/ExecutionContext.php → src/Script/Interpreter/ExecutionContext.php
@@ -1,6 +1,6 @@
 <?php declare(strict_types=1);
 
-namespace BitWasp\Bitcoin\Script;
+namespace BitWasp\Bitcoin\Script\Interpreter;
 
 use BitWasp\Buffertools\BufferInterface;
 
@@ -100,6 +100,14 @@ public function hasValidationWeightSet(): bool
         return null !== $this->validationWeightLeft;
     }
 
+    /**
+     * @return null|int
+     */
+    public function getValidationWeightLeft()
+    {
+        return $this->validationWeightLeft;
+    }
+
     public function setValidationWeightLeft(int $weight)
     {
         $this->validationWeightLeft = $weight;

diff --git a/src/Script/Interpreter/Interpreter.php b/src/Script/Interpreter/Interpreter.php
@@ -12,7 +12,7 @@
 use BitWasp\Bitcoin\Exceptions\ScriptRuntimeException;
 use BitWasp\Bitcoin\Exceptions\SignatureNotCanonical;
 use BitWasp\Bitcoin\Script\Classifier\OutputClassifier;
-use BitWasp\Bitcoin\Script\ExecutionContext;
+use BitWasp\Bitcoin\Script\Interpreter\ExecutionContext;
 use BitWasp\Bitcoin\Script\Opcodes;
 use BitWasp\Bitcoin\Script\Script;
 use BitWasp\Bitcoin\Script\ScriptFactory;
@@ -196,7 +196,7 @@ private function verifyTaprootCommitment(BufferInterface $control, BufferInterfa
             }
         }
         $t = Hash::taggedSha256("TapTweak", Buffertools::concat($p, $k));
-        return $Q->checkPayToContract($P, $t, ($control->getBinary()[0] & 1) == 1);
+        return $Q->checkPayToContract($P, $t, (ord($control->getBinary()[0]) & 1) == 1);
     }
 
     /**
@@ -305,7 +305,6 @@ private function verifyWitnessProgram(WitnessProgram $witnessProgram, ScriptWitn
                 $witnessCount--;
             }
             $execContext->setAnnexCheckDone();
-
             if ($witnessCount === 1) {
                 // key spend path - doesn't use the interpreter, directly checks signature
                 $signature = $scriptWitness[count($scriptWitness) - 1];
@@ -343,7 +342,7 @@ private function verifyWitnessProgram(WitnessProgram $witnessProgram, ScriptWitn
                 }
 
                 // return true at this stage, need further work to proceed
-                return $this->executeWitnessProgram($scriptWitness, $scriptPubKey, SigHash::TAPSCRIPT, $flags, $checker, $execContext);
+                return $this->executeWitnessProgram($scriptWitness, new Script($scriptPubKey), SigHash::TAPSCRIPT, $flags, $checker, $execContext);
             }
         }
 
@@ -502,6 +501,54 @@ public function checkExec(Stack $vfStack, bool $value): bool
         return (bool) $ret;
     }
 
+    private function evalChecksigPreTapscript(BufferInterface $sig, BufferInterface $key, ScriptInterface $scriptPubKey, int $hashStartPos, int $flags, CheckerBase $checker, int $sigVersion, bool &$success): bool
+    {
+        assert($sigVersion === SigHash::V0 || $sigVersion === SigHash::V1);
+        $scriptCode = new Script($scriptPubKey->getBuffer()->slice($hashStartPos));
+        // encoding is checked in checker
+        $success = $checker->checkSig($scriptCode, $sig, $key, $sigVersion, $flags);
+        return true;
+    }
+
+    private function evalChecksigTapscript(BufferInterface $sig, BufferInterface $key, int $flags, CheckerBase $checker, int $sigVersion, ExecutionContext $execContext, bool &$success): bool
+    {
+        assert($sigVersion === SigHash::TAPSCRIPT);
+        $success = $sig->getSize() > 0;
+        if ($success) {
+            assert($execContext->hasValidationWeightSet());
+            $execContext->setValidationWeightLeft($execContext->getValidationWeightLeft() - VALIDATION_WEIGHT_OFFSET);
+            if ($execContext->getValidationWeightLeft() < 0) {
+                return false;
+            }
+        }
+        if ($key->getSize() === 0) {
+            return false;
+        } else if ($key->getSize() === 32) {
+            if ($success && !$checker->checkSigSchnorr($sig, $key, $sigVersion, $execContext)) {
+                return false;
+            }
+        } else {
+            if ($flags & self::VERIFY_DISCOURAGE_UPGRADABLE_PUBKEYTYPE) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    private function evalChecksig(BufferInterface $sig, BufferInterface $key, ScriptInterface $scriptPubKey, int $hashStartPos, int $flags, CheckerBase $checker, int $sigVersion, ExecutionContext $execContext, bool &$success): bool
+    {
+        switch ($sigVersion) {
+            case SigHash::V0:
+            case SigHash::V1:
+                return $this->evalChecksigPreTapscript($sig, $key, $scriptPubKey, $hashStartPos, $flags, $checker, $sigVersion, $success);
+            case SigHash::TAPSCRIPT:
+                return $this->evalChecksigTapscript($sig, $key, $flags, $checker, $sigVersion, $execContext, $success);
+            case SigHash::TAPROOT:
+                break;
+        };
+        assert(false);
+    }
+
     /**
      * @param ScriptInterface $script
      * @param Stack $mainStack
@@ -513,6 +560,9 @@ public function checkExec(Stack $vfStack, bool $value): bool
      */
     public function evaluate(ScriptInterface $script, Stack $mainStack, int $sigVersion, int $flags, CheckerBase $checker, ExecutionContext $execContext = null): bool
     {
+        if ($execContext === null) {
+            $execContext = new ExecutionContext();
+        }
         $hashStartPos = 0;
         $opCount = 0;
         $zero = gmp_init(0, 10);
@@ -1033,9 +1083,10 @@ public function evaluate(ScriptInterface $script, Stack $mainStack, int $sigVers
                             $vchPubKey = $mainStack[-1];
                             $vchSig = $mainStack[-2];
 
-                            $scriptCode = new Script($script->getBuffer()->slice($hashStartPos));
-
-                            $success = $checker->checkSig($scriptCode, $vchSig, $vchPubKey, $sigVersion, $flags, $execContext);
+                            $success = false;
+                            if (!$this->evalChecksig($vchSig, $vchPubKey, $script, $hashStartPos, $flags, $checker, $sigVersion, $execContext, $success)) {
+                                return false;
+                            }
 
                             $mainStack->pop();
                             $mainStack->pop();

diff --git a/src/Script/Interpreter/InterpreterInterface.php b/src/Script/Interpreter/InterpreterInterface.php
@@ -81,7 +81,7 @@ interface InterpreterInterface
     const VERIFY_DISCOURAGE_UPGRADABLE_ANNEX = 1 << 19;
 
     const VERIFY_DISCOURAGE_OP_SUCCESS = 1 << 20;
-
+    const VERIFY_DISCOURAGE_UPGRADABLE_PUBKEYTYPE = 1 << 21;
     // Verify CHECKSEQUENCEVERIFY
     //
     // See BIP112 for details.

diff --git a/src/Script/Interpreter/interpreter_constants.php b/src/Script/Interpreter/interpreter_constants.php
@@ -0,0 +1,5 @@
+<?php declare(strict_types=1);
+
+namespace BitWasp\Bitcoin\Script\Interpreter;
+
+const VALIDATION_WEIGHT_OFFSET = 50;
diff --git a/src/Script/script_constants.php b/src/Script/script_constants.php
diff --git a/src/Transaction/SignatureHash/TaprootHasher.php b/src/Transaction/SignatureHash/TaprootHasher.php
@@ -5,7 +5,7 @@
 namespace BitWasp\Bitcoin\Transaction\SignatureHash;
 
 use BitWasp\Bitcoin\Crypto\Hash;
-use BitWasp\Bitcoin\Script\ExecutionContext;
+use BitWasp\Bitcoin\Script\Interpreter\ExecutionContext;
 use BitWasp\Bitcoin\Script\PrecomputedData;
 use BitWasp\Bitcoin\Script\ScriptInterface;
 use BitWasp\Bitcoin\Serializer\Transaction\OutPointSerializer;