Merge #8499: Add several policy limits and disable uncompressed keys for segwit scripts

67d6ee1 remove redundant tests in p2p-segwit.py (Johnson Lau)
9260085 test segwit uncompressed key fixes (Johnson Lau)
248f3a7 Fix ismine and addwitnessaddress: no uncompressed keys in segwit (Pieter Wuille)
b811124 [qa] Add tests for uncompressed pubkeys in segwit (Suhas Daftuar)
9f0397a Make test framework produce lowS signatures (Johnson Lau)
4c0c25a Require compressed keys in segwit as policy and disable signing with uncompressed keys for segwit scripts (Johnson Lau)
3ade2f6 Add standard limits for P2WSH with tests (Johnson Lau)

1 files changed, 22 insertions, 6 deletions

diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index 41756ea71..836cf9ee3 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;
 }
 
@@ -879,7 +895,7 @@ 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;
                     }
@@ -953,7 +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;
                         }