go: implement leafop key/value prefixes

go/ops.go

@@ -24,11 +24,11 @@ func (op *LeafOp) Apply(key []byte, value []byte) ([]byte, error) {
 	if len(value) == 0 {
 		return nil, errors.New("Leaf op needs value")
 	}
-	pkey, err := prepareLeafData(op.PrehashKey, op.Length, key)
+	pkey, err := prepareLeafData(op.PrehashKey, op.Length, op.PrefixPrehashKey, key)
 	if err != nil {
 		return nil, errors.Wrap(err, "prehash key")
 	}
-	pvalue, err := prepareLeafData(op.PrehashValue, op.Length, value)
+	pvalue, err := prepareLeafData(op.PrehashValue, op.Length, op.PrefixPrehashValue, value)
 	if err != nil {
 		return nil, errors.Wrap(err, "prehash value")
 	}
@@ -56,6 +56,12 @@ func (op *LeafOp) CheckAgainstSpec(spec *ProofSpec) error {
 	if !bytes.HasPrefix(op.Prefix, lspec.Prefix) {
 		return errors.Errorf("Leaf Prefix doesn't start with %X", lspec.Prefix)
 	}
+	if !bytes.HasPrefix(op.PrefixPrehashKey, lspec.PrefixPrehashKey) {
+		return errors.Errorf("Leaf PrefixPrehashKey doesn't start with %X", lspec.PrefixPrehashKey)
+	}
+	if !bytes.HasPrefix(op.PrefixPrehashValue, lspec.PrefixPrehashKey) {
+		return errors.Errorf("Leaf PrefixPrehashValue doesn't start with %X", lspec.PrefixPrehashValue)
+	}
 	return nil
 }
 
@@ -89,9 +95,11 @@ func (op *InnerOp) CheckAgainstSpec(spec *ProofSpec) error {
 	return nil
 }
 
-func prepareLeafData(hashOp HashOp, lengthOp LengthOp, data []byte) ([]byte, error) {
-	// TODO: lengthop before or after hash ???
-	hdata, err := doHashOrNoop(hashOp, data)
+func prepareLeafData(hashOp HashOp, lengthOp LengthOp, prefix []byte, data []byte) ([]byte, error) {
+	prefixed := make([]byte, 0, len(prefix)+len(data))
+	prefixed = append(prefixed, prefix...)
+	prefixed = append(prefixed, data...)
+	hdata, err := doHashOrNoop(hashOp, prefixed)
 	if err != nil {
 		return nil, err
 	}

testdata/TestLeafOpData.json

@@ -57,6 +57,18 @@
     "IsErr": false,
     "Expected": "h+BIPo+2JK7y4vexP0FmzaSFuqjjn0N8g9dMlL7bFI8="
   },
+  "hash with prefixed prehash and length prefix": {
+    "Op": {
+      "hash": 1,
+      "prehash_value": 1,
+      "length": 1,
+      "prefix_prehash_value": "eWU="
+    },
+    "Key": "Zm9vZA==",
+    "Value": "dCBhbm90aGVyIGxvbmcgc3RyaW5n",
+    "IsErr": false,
+    "Expected": "h+BIPo+2JK7y4vexP0FmzaSFuqjjn0N8g9dMlL7bFI8="
+  },
   "requires key": {
     "Op": {
       "hash": 1