1 files changed, 41 insertions, 7 deletions

diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index 47ea261e31..836cf9ee35 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -79,8 +79,20 @@ bool static IsCompressedOrUncompressedPubKey(const valtype &vchPubKey) {
             return false;
         }
     } else {
-          //  Non-canonical public key: neither compressed nor uncompressed
-          return false;
+        //  Non-canonical public key: neither compressed nor uncompressed
+        return false;
+    }
+    return true;
+}
+
+bool static IsCompressedPubKey(const valtype &vchPubKey) {
+    if (vchPubKey.size() != 33) {
+        //  Non-canonical public key: invalid length for compressed key
+        return false;
+    }
+    if (vchPubKey[0] != 0x02 && vchPubKey[0] != 0x03) {
+        //  Non-canonical public key: invalid prefix for compressed key
+        return false;
     }
     return true;
 }
@@ -199,10 +211,14 @@ bool CheckSignatureEncoding(const vector<unsigned char> &vchSig, unsigned int fl
     return true;
 }
 
-bool static CheckPubKeyEncoding(const valtype &vchSig, unsigned int flags, ScriptError* serror) {
-    if ((flags & SCRIPT_VERIFY_STRICTENC) != 0 && !IsCompressedOrUncompressedPubKey(vchSig)) {
+bool static CheckPubKeyEncoding(const valtype &vchPubKey, unsigned int flags, const SigVersion &sigversion, ScriptError* serror) {
+    if ((flags & SCRIPT_VERIFY_STRICTENC) != 0 && !IsCompressedOrUncompressedPubKey(vchPubKey)) {
         return set_error(serror, SCRIPT_ERR_PUBKEYTYPE);
     }
+    // Only compressed keys are accepted in segwit
+    if ((flags & SCRIPT_VERIFY_WITNESS_PUBKEYTYPE) != 0 && sigversion == SIGVERSION_WITNESS_V0 && !IsCompressedPubKey(vchPubKey)) {
+        return set_error(serror, SCRIPT_ERR_WITNESS_PUBKEYTYPE);
+    }
     return true;
 }
 
@@ -428,6 +444,12 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
                         if (stack.size() < 1)
                             return set_error(serror, SCRIPT_ERR_UNBALANCED_CONDITIONAL);
                         valtype& vch = stacktop(-1);
+                        if (sigversion == SIGVERSION_WITNESS_V0 && (flags & SCRIPT_VERIFY_MINIMALIF)) {
+                            if (vch.size() > 1)
+                                return set_error(serror, SCRIPT_ERR_MINIMALIF);
+                            if (vch.size() == 1 && vch[0] != 1)
+                                return set_error(serror, SCRIPT_ERR_MINIMALIF);
+                        }
                         fValue = CastToBool(vch);
                         if (opcode == OP_NOTIF)
                             fValue = !fValue;
@@ -873,12 +895,15 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
                         scriptCode.FindAndDelete(CScript(vchSig));
                     }
 
-                    if (!CheckSignatureEncoding(vchSig, flags, serror) || !CheckPubKeyEncoding(vchPubKey, flags, serror)) {
+                    if (!CheckSignatureEncoding(vchSig, flags, serror) || !CheckPubKeyEncoding(vchPubKey, flags, sigversion, serror)) {
                         //serror is set
                         return false;
                     }
                     bool fSuccess = checker.CheckSig(vchSig, vchPubKey, scriptCode, sigversion);
 
+                    if (!fSuccess && (flags & SCRIPT_VERIFY_NULLFAIL) && vchSig.size())
+                        return set_error(serror, SCRIPT_ERR_SIG_NULLFAIL);
+
                     popstack(stack);
                     popstack(stack);
                     stack.push_back(fSuccess ? vchTrue : vchFalse);
@@ -908,6 +933,9 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
                     if (nOpCount > MAX_OPS_PER_SCRIPT)
                         return set_error(serror, SCRIPT_ERR_OP_COUNT);
                     int ikey = ++i;
+                    // ikey2 is the position of last non-signature item in the stack. Top stack item = 1.
+                    // With SCRIPT_VERIFY_NULLFAIL, this is used for cleanup if operation fails.
+                    int ikey2 = nKeysCount + 2;
                     i += nKeysCount;
                     if ((int)stack.size() < i)
                         return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
@@ -941,7 +969,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
                         // Note how this makes the exact order of pubkey/signature evaluation
                         // distinguishable by CHECKMULTISIG NOT if the STRICTENC flag is set.
                         // See the script_(in)valid tests for details.
-                        if (!CheckSignatureEncoding(vchSig, flags, serror) || !CheckPubKeyEncoding(vchPubKey, flags, serror)) {
+                        if (!CheckSignatureEncoding(vchSig, flags, serror) || !CheckPubKeyEncoding(vchPubKey, flags, sigversion, serror)) {
                             // serror is set
                             return false;
                         }
@@ -964,8 +992,14 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
                     }
 
                     // Clean up stack of actual arguments
-                    while (i-- > 1)
+                    while (i-- > 1) {
+                        // If the operation failed, we require that all signatures must be empty vector
+                        if (!fSuccess && (flags & SCRIPT_VERIFY_NULLFAIL) && !ikey2 && stacktop(-1).size())
+                            return set_error(serror, SCRIPT_ERR_SIG_NULLFAIL);
+                        if (ikey2 > 0)
+                            ikey2--;
                         popstack(stack);
+                    }
 
                     // A bug causes CHECKMULTISIG to consume one extra argument
                     // whose contents were not checked in any way.