Improve crypto

- Re-organize packages to be consistent
- Add Key store tests

src/main/java/io/kamax/mxisd/crypto/SignatureManager.java

@@ -0,0 +1,64 @@
+/*
+ * mxisd - Matrix Identity Server Daemon
+ * Copyright (C) 2019 Kamax Sàrl
+ *
+ * https://www.kamax.io/
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package io.kamax.mxisd.crypto;
+
+import com.google.gson.JsonObject;
+
+import java.nio.charset.StandardCharsets;
+
+public interface SignatureManager {
+
+    /**
+     * Sign the message and produce a <code>signatures</code> object that can directly be added to the object being signed.
+     *
+     * @param domain  The domain under which the signature should be added
+     * @param message The message to sign
+     * @return The <code>signatures</code> object
+     */
+    JsonObject signMessageGson(String domain, String message);
+
+    /**
+     * Sign the canonical form of a JSON object.
+     *
+     * @param obj The JSON object to canonicalize and sign
+     * @return The signature
+     */
+    Signature sign(JsonObject obj);
+
+    /**
+     * Sign the message, using UTF-8 as decoding character set.
+     *
+     * @param message The UTF-8 encoded message
+     * @return The signature
+     */
+    default Signature sign(String message) {
+        return sign(message.getBytes(StandardCharsets.UTF_8));
+    }
+
+    /**
+     * Sign the data.
+     *
+     * @param data The data to sign
+     * @return The signature
+     */
+    Signature sign(byte[] data);
+
+}