scripts: add error for >n signatures with multisig

src/scripts.js

@@ -238,9 +238,13 @@ function multisigInput(signatures, scriptPubKey) {
   if (scriptPubKey) {
     assert(isMultisigOutput.call(scriptPubKey))
 
-    var m = scriptPubKey.chunks[0]
-    var k = m - (opcodes.OP_1 - 1)
-    assert(k <= signatures.length, 'Not enough signatures provided')
+    var mOp = scriptPubKey.chunks[0]
+    var nOp = scriptPubKey.chunks[scriptPubKey.chunks.length - 2]
+    var m = mOp - (opcodes.OP_1 - 1)
+    var n = nOp - (opcodes.OP_1 - 1)
+
+    assert(signatures.length >= m, 'Not enough signatures provided')
+    assert(signatures.length <= n, 'Too many signatures provided')
   }
 
   return Script.fromChunks([].concat(opcodes.OP_0, signatures))

test/fixtures/scripts.json

@@ -101,6 +101,19 @@
           "304402207515cf147d201f411092e6be5a64a6006f9308fad7b2a8fdaab22cd86ce764c202200974b8aca7bf51dbf54150d3884e1ae04f675637b926ec33bf75939446f6ca2801"
         ],
         "scriptPubKey": false
+      },
+      {
+        "exception": "Too many signatures provided",
+        "pubKeys": [
+          "02359c6e3f04cefbf089cf1d6670dc47c3fb4df68e2bad1fa5a369f9ce4b42bbd1",
+          "0395a9d84d47d524548f79f435758c01faec5da2b7e551d3b8c995b7e06326ae4a"
+        ],
+        "signatures": [
+          "304402207515cf147d201f411092e6be5a64a6006f9308fad7b2a8fdaab22cd86ce764c202200974b8aca7bf51dbf54150d3884e1ae04f675637b926ec33bf75939446f6ca2801",
+          "3045022100ef253c1faa39e65115872519e5f0a33bbecf430c0f35cf562beabbad4da24d8d02201742be8ee49812a73adea3007c9641ce6725c32cd44ddb8e3a3af460015d140501",
+          "3045022100ef253c1faa39e65115872519e5f0a33bbecf430c0f35cf562beabbad4da24d8d02201742be8ee49812a73adea3007c9641ce6725c32cd44ddb8e3a3af460015d140501"
+        ],
+        "scriptPubKey": false
       }
     ]
   }