gb vendor fetch github.com/matrix-org/gomatrixserverlib/

vendor/src/github.com/matrix-org/gomatrixserverlib/signing.go

@@ -0,0 +1,120 @@
+/* Copyright 2016-2017 Vector Creations Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package gomatrixserverlib
+
+import (
+	"encoding/json"
+	"fmt"
+	"golang.org/x/crypto/ed25519"
+)
+
+// SignJSON signs a JSON object returning a copy signed with the given key.
+// https://matrix.org/docs/spec/server_server/unstable.html#signing-json
+func SignJSON(signingName, keyID string, privateKey ed25519.PrivateKey, message []byte) ([]byte, error) {
+	var object map[string]*json.RawMessage
+	var signatures map[string]map[string]Base64String
+	if err := json.Unmarshal(message, &object); err != nil {
+		return nil, err
+	}
+
+	rawUnsigned, hasUnsigned := object["unsigned"]
+	delete(object, "unsigned")
+
+	if rawSignatures := object["signatures"]; rawSignatures != nil {
+		if err := json.Unmarshal(*rawSignatures, &signatures); err != nil {
+			return nil, err
+		}
+		delete(object, "signatures")
+	} else {
+		signatures = map[string]map[string]Base64String{}
+	}
+
+	unsorted, err := json.Marshal(object)
+	if err != nil {
+		return nil, err
+	}
+
+	canonical, err := CanonicalJSON(unsorted)
+	if err != nil {
+		return nil, err
+	}
+
+	signature := Base64String(ed25519.Sign(privateKey, canonical))
+
+	signaturesForEntity := signatures[signingName]
+	if signaturesForEntity != nil {
+		signaturesForEntity[keyID] = signature
+	} else {
+		signatures[signingName] = map[string]Base64String{keyID: signature}
+	}
+
+	var rawSignatures json.RawMessage
+	rawSignatures, err = json.Marshal(signatures)
+	if err != nil {
+		return nil, err
+	}
+
+	object["signatures"] = &rawSignatures
+	if hasUnsigned {
+		object["unsigned"] = rawUnsigned
+	}
+
+	return json.Marshal(object)
+}
+
+// VerifyJSON checks that the entity has signed the message using a particular key.
+func VerifyJSON(signingName, keyID string, publicKey ed25519.PublicKey, message []byte) error {
+	var object map[string]*json.RawMessage
+	var signatures map[string]map[string]Base64String
+	if err := json.Unmarshal(message, &object); err != nil {
+		return err
+	}
+	delete(object, "unsigned")
+
+	if object["signatures"] == nil {
+		return fmt.Errorf("No signatures")
+	}
+
+	if err := json.Unmarshal(*object["signatures"], &signatures); err != nil {
+		return err
+	}
+	delete(object, "signatures")
+
+	signature, ok := signatures[signingName][keyID]
+	if !ok {
+		return fmt.Errorf("No signature from %q with ID %q", signingName, keyID)
+	}
+
+	if len(signature) != ed25519.SignatureSize {
+		return fmt.Errorf("Bad signature length from %q with ID %q", signingName, keyID)
+	}
+
+	unsorted, err := json.Marshal(object)
+	if err != nil {
+		return err
+	}
+
+	canonical, err := CanonicalJSON(unsorted)
+	if err != nil {
+		return err
+	}
+
+	if !ed25519.Verify(publicKey, canonical, signature) {
+		return fmt.Errorf("Bad signature from %q with ID %q", signingName, keyID)
+	}
+
+	return nil
+}