From 97e7901a3a7403cd5a5a027ad83e9674e3b950be Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Thu, 18 Apr 2013 22:17:05 +0200
Subject: [PATCH] Do not invoke DoS for non-canonical sigs

---
 src/main.cpp | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/main.cpp b/src/main.cpp
index 6f3b5da961..aace382d8b 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1438,8 +1438,16 @@ bool CTransaction::CheckInputs(CValidationState &state, CCoinsViewCache &inputs,
                 if (pvChecks) {
                     pvChecks->push_back(CScriptCheck());
                     check.swap(pvChecks->back());
-                } else if (!check())
+                } else if (!check()) {
+                    if (flags & SCRIPT_VERIFY_STRICTENC) {
+                        // For now, check whether the failure was caused by non-canonical
+                        // encodings or not; if so, don't trigger DoS protection.
+                        CScriptCheck check(coins, *this, i, flags & (~SCRIPT_VERIFY_STRICTENC), 0);
+                        if (check())
+                            return state.Invalid();
+                    }
                     return state.DoS(100,false);
+                }
             }
         }
     }