Chrome OS uWeave Characteristics Server

components/proximity_auth/ble/bluetooth_low_energy_eid_generator.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_PROXIMITY_AUTH_BLE_BLUETOOTH_LOW_ENERGY_WEAVE_EID_GENERATOR_H_
+#define COMPONENTS_PROXIMITY_AUTH_BLE_BLUETOOTH_LOW_ENERGY_WEAVE_EID_GENERATOR_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <memory>
+
+#include "components/proximity_auth/remote_device.h"
+
+namespace proximity_auth {
+namespace weave {
+
+// Represent a EID generator for a single device.
+// EID is ephemeral id needed to be included for the advertisement for security
+// and privacy reasons.
+// It has the repsonsiblity of getting the correct EID seed out of the
+// RemoteDevice and encode the seed with the timestamp to get the EID
+class BluetoothLowEnergyEidGenerator {
+ public:
+  class Factory {
+   public:
+    // TODO(jingxuy): this is just stop compiler from complaining.
+    static std::unique_ptr<BluetoothLowEnergyEidGenerator> NewInstance() {
+      return std::unique_ptr<BluetoothLowEnergyEidGenerator>(
+          new BluetoothLowEnergyEidGenerator());
+    }
+
+    // Exposed for testing.
+    static void SetInstanceForTesting(Factory* factory);
+
+   protected:
+    // Exposed for testing.
+    virtual std::unique_ptr<BluetoothLowEnergyEidGenerator> BuildInstance();
+
+   private:
+    static Factory* factory_instance_;
+  };
+
+  typedef uint8_t EidSeed[32];
+
+  // TODO(tether-dev): Make this actually generate EID.
+  // This function should look at the time and get the correct seed out of the
+  // remote device. If this seed is different from the current_seed_, then
+  // re-seed the generator. Otherwise generate based on time and stuff.
+  uint16_t GetEid(const RemoteDevice& device) { return 42; }

[Kyle Horimoto, 2016/07/29 03:15:39]

1) Your function should take a public key as a parameter.
2) Your function should return a current and, if possible, an adjacent object
containing a data array, a start timestamp, and a stop timestamp.

[jingxuy, 2016/07/29 18:45:43]

I thought we agreed on it take RemoteDevice? But I don't think getting the exact
parameter and return type is high priority now. Since this is a place holder,
you guys are free to change it to anything. Only one function calls this
function anyway and that function is mostly left as TODO. I'm thinking about
changing the return type since it's more structurally important.

[Kyle Horimoto, 2016/07/29 19:04:18]

The public key of the local device as well as metadata about the remote device
are both needed to compute the EID. If you want, you can just pass a null public
key for the stub implementation. Either way, you certainly do need to return a
valid return value. A short is not a valid EID.

[jingxuy, 2016/07/29 20:26:01]

what's the type of public key? Are you talking about the string contained in
RemoteDevice?

[Kyle Horimoto, 2016/07/29 21:07:45]

Yep, though it needs to be converted into a data array first. Ask tengs@ how to
do this conversion - I think its just c_str(), but I'm not positive.

+
+ protected:
+  BluetoothLowEnergyEidGenerator(){};
+};
+
+}  // namespace weave
+
+}  // namespace proximity_auth
+
+#endif