Index: src/script/interpreter.cpp
===================================================================
--- src/script/interpreter.cpp
+++ src/script/interpreter.cpp
@@ -335,9 +335,9 @@
                 return set_error(serror, SCRIPT_ERR_OP_COUNT);
             }
 
-            if (opcode == OP_LEFT || opcode == OP_RIGHT || opcode == OP_INVERT ||
-                opcode == OP_2MUL || opcode == OP_2DIV || opcode == OP_MUL ||
-                opcode == OP_LSHIFT || opcode == OP_RSHIFT) {
+            if (opcode == OP_RIGHT || opcode == OP_INVERT || opcode == OP_2MUL ||
+                opcode == OP_2DIV || opcode == OP_MUL || opcode == OP_LSHIFT ||
+                opcode == OP_RSHIFT) {
                 // Disabled opcodes.
                 return set_error(serror, SCRIPT_ERR_DISABLED_OPCODE);
             }
@@ -1287,6 +1287,25 @@
                         }
                     } break;
 
+                    //
+                    // Conversion operations
+                    //
+                    case OP_BIN2NUM: {
+                        // (in -- out)
+                        if (stack.size() < 1) {
+                            return set_error(
+                                serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
+                        }
+                        valtype bin = stacktop(-1);
+                        std::reverse(bin.begin(), bin.end()); //be2le
+                        CScriptNum num(bin, false);
+                        if (num > (INT_MAX>>1) || num < (INT_MIN>>1)) {
+                            return set_error(serror, SCRIPT_ERR_INVALID_BIN2NUM_OPERATION);
+                        }
+                        stack.pop_back();
+                        stack.push_back(num.getvch());
+                    } break;
+
                     default:
                         return set_error(serror, SCRIPT_ERR_BAD_OPCODE);
                 }
Index: src/script/script.h
===================================================================
--- src/script/script.h
+++ src/script/script.h
@@ -103,7 +103,6 @@
     // splice ops
     OP_CAT = 0x7e,
     OP_SPLIT = 0x7f,
-    OP_LEFT = 0x80,
     OP_RIGHT = 0x81,
     OP_SIZE = 0x82,
 
@@ -162,6 +161,7 @@
     OP_CHECKMULTISIGVERIFY = 0xaf,
 
     // expansion
+    OP_BIN2NUM = 0x80,
     OP_NOP1 = 0xb0,
     OP_CHECKLOCKTIMEVERIFY = 0xb1,
     OP_NOP2 = OP_CHECKLOCKTIMEVERIFY,
Index: src/script/script.cpp
===================================================================
--- src/script/script.cpp
+++ src/script/script.cpp
@@ -123,8 +123,6 @@
             return "OP_CAT";
         case OP_SPLIT:
             return "OP_SPLIT";
-        case OP_LEFT:
-            return "OP_LEFT";
         case OP_RIGHT:
             return "OP_RIGHT";
         case OP_SIZE:
Index: src/script/script_error.h
===================================================================
--- src/script/script_error.h
+++ src/script/script_error.h
@@ -37,6 +37,7 @@
     SCRIPT_ERR_DIV_BY_ZERO,
     SCRIPT_ERR_MOD_BY_ZERO,
     SCRIPT_ERR_INVALID_SPLIT_RANGE,
+    SCRIPT_ERR_INVALID_BIN2NUM_OPERATION,
 
     /* CHECKLOCKTIMEVERIFY and CHECKSEQUENCEVERIFY */
     SCRIPT_ERR_NEGATIVE_LOCKTIME,
Index: src/script/script_error.cpp
===================================================================
--- src/script/script_error.cpp
+++ src/script/script_error.cpp
@@ -54,6 +54,8 @@
             return "Invalid modulo operation";
         case SCRIPT_ERR_INVALID_SPLIT_RANGE:
             return "Invalid OP_SPLIT range";
+        case SCRIPT_ERR_INVALID_BIN2NUM_OPERATION:
+            return "Invalid OP_BIN2NUM operation (check operand values)";
         case SCRIPT_ERR_NEGATIVE_LOCKTIME:
             return "Negative locktime";
         case SCRIPT_ERR_UNSATISFIED_LOCKTIME: