Diff: source/EIDFrame.h

Revision:

0:1c7da5f83647

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/source/EIDFrame.h	Tue Nov 29 06:29:10 2016 +0000
@@ -0,0 +1,224 @@
+/*
+ * Copyright (c) 2016, Google Inc, All Rights Reserved
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * 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.
+ */
+
+#ifndef __EIDFRAME_H__
+#define __EIDFRAME_H__
+
+#include <string.h>
+#include "EddystoneTypes.h"
+#include "mbedtls/aes.h"
+#include "mbedtls/ecdh.h"
+#include "mbedtls/md.h"
+#include "mbedtls/entropy.h"
+#include "mbedtls/ctr_drbg.h"
+#include "aes_eax.h"
+
+/**
+ * Class that encapsulates data that belongs to the Eddystone-EID frame. For
+ * more information refer to https://github.com/google/eddystone/tree/master/eddystone-EID.
+ */
+class EIDFrame
+{
+public:
+    static const uint8_t SALT = 0xff;
+    static const uint8_t EID_LENGTH = 8;
+    static const int EID_SUCCESS = 0;
+    static const int EID_RC_SS_IS_ZERO = -1;
+    static const int EID_RND_FAIL = -2;
+    static const int EID_GRP_FAIL = -3;
+    static const int EID_GENKEY_FAIL = -4;
+
+    /**
+     * Construct a new instance of this class.
+     */
+    EIDFrame();
+    
+    /**
+     * Clear frame (internally represented by length = 0 )
+     */
+    void clearFrame(uint8_t* frame);
+    
+    /**
+     * Construct the raw bytes of the Eddystone-EID frame that will be directly
+     * used in the advertising packets.
+     *
+     * @param[in] rawFrame
+     *              Pointer to the location where the raw frame will be stored.
+     * @param[in] advPowerLevel
+     *              Power level value included in the raw frame.
+     * @param[in] eidData
+     *              The actual 16-byte EID data in the raw frame.
+     */
+    void setData(uint8_t* rawFrame, int8_t advTxPower, const uint8_t* eidData);
+    
+    /**
+     * Get the EID frame data from the Eddystone-EID frame.
+     * 
+     * @param[in] rawFrame
+     *              Pointer to the location where the raw frame will be stored.
+     *
+     * @return A pointer to the bytes of the Eddystone-EID frame data.
+     */
+    uint8_t* getData(uint8_t* rawFrame);
+    
+    /**
+     * Get the length of the EID frame data from the Eddystone-EID frame.
+     * 
+     * @param[in] rawFrame
+     *              Pointer to the location where the raw frame will be stored.
+     *
+     * @return The size in bytes of the Eddystone-EID frame.
+     */
+    uint8_t  getDataLength(uint8_t* rawFrame);
+    
+    /**
+     * Get the EID Adv data from the Eddystone-EID frame.
+     * This is the full service data included in the BLE service data params
+     * 
+     * @param[in] rawFrame
+     *              Pointer to the location where the raw frame will be stored.
+     *
+     * @return A pointer to the bytes of the Eddystone-EID Adv frame data.
+     */
+    uint8_t* getAdvFrame(uint8_t* rawFrame);
+    
+    /**
+     * Get the length of the EID Adv data from the Eddystone-EID frame.
+     * 
+     * @param[in] rawFrame
+     *              Pointer to the location where the raw frame will be stored.
+     *
+     * @return The size in bytes of the Eddystone-EID Adv frame data.
+     */
+    uint8_t getAdvFrameLength(uint8_t* rawFrame);
+
+    /**
+     * Get just the EID data from the Eddystone-EID frame.
+     * 
+     * @param[in] rawFrame
+     *              Pointer to the location where the raw frame will be stored.
+     *
+     * @return A pointer to the bytes of the EID in the Eddystone-EID frame.
+     */
+    uint8_t* getEid(uint8_t* rawFrame);
+    
+    /**
+     * Get the length of just the EID data from the Eddystone-EID frame.
+     * 
+     * @param[in] rawFrame
+     *              Pointer to the location where the raw frame will be stored.
+     *
+     * @return The size in bytes of the EID in the Eddystone-EID frame.
+     */
+    uint8_t getEidLength(uint8_t* rawFrame);
+    
+    /**
+     * Set the Adv TX Power in the frame. This is necessary because the adv
+     * Tx Power might be updated independent of the data bytes
+     * 
+     * @param[in] rawFrame
+     *              Pointer to the location where the raw frame will be stored.
+     * @param[in] advPowerLevel
+     *              Power level value included in the raw frame.
+     *
+     */
+    void setAdvTxPower(uint8_t* rawFrame, int8_t advTxPower);
+    
+
+    /**
+     * Generate the beacon private and public keys. This should be called on
+     * every restart of the beacon.
+     * 
+     * @param[out] beaconPrivateEcdhKey
+     *              Pointer to the beacon private key array.
+     * @param[out] beaconPublicEcdhKey
+     *              Pointer to the beacon public key array.
+     *
+     */
+    int genBeaconKeys(PrivateEcdhKey_t beaconPrivateEcdhKey, PublicEcdhKey_t beaconPublicEcdhKey);
+
+    /**
+     * Update the EID frame. Tests if its time to rotate the EID payload, and if due, calculates and establishes the new value
+     * 
+     * @param[in] *rawFrame
+     *              Pointer to the location where the raw frame will be stored.
+     * @param[in] *eidIdentityKey
+     *              Eid key used to regenerate the EID id.
+     * @param[in] rotationPeriodExp
+     *              EID rotation time as an exponent k : 2^k seconds
+     * @param[in] timeSecs
+     *              time in seconds
+     *
+     */
+    void update(uint8_t* rawFrame, uint8_t* eidIdentityKey, uint8_t rotationPeriodExp,  uint32_t timeSecs);
+    
+    /**
+     * genEcdhSharedKey generates the eik value for inclusion in the EID ADV packet
+     *
+     * @param[in] beaconPrivateEcdhKey
+     *              The beacon's private ECDH key, generated by genBeaconKeys()
+     * @param[in] beaconPublicEcdhKey
+     *              The beacon's public ECDH key, generated by genBeaconKeys()
+     * @param[in] serverPublicEcdhKey
+     *              The server's public ECDH key
+     * @param[out] eidIdentityKey
+     *              Identity key for this beacon and server combination
+     */
+    int genEcdhSharedKey(PrivateEcdhKey_t beaconPrivateEcdhKey, PublicEcdhKey_t beaconPublicEcdhKey, PublicEcdhKey_t serverPublicEcdhKey, EidIdentityKey_t eidIdentityKey);
+    
+    /**
+     *  The byte ID of an Eddystone-EID frame.
+     */
+    static const uint8_t FRAME_TYPE_EID = 0x30;
+
+private:
+    
+    // Declare context for crypto functions
+    mbedtls_entropy_context entropy;
+    mbedtls_ctr_drbg_context ctr_drbg;
+    mbedtls_ecdh_context ecdh_ctx;
+    mbedtls_md_context_t md_ctx;
+
+    /**
+     * The size (in bytes) of an Eddystone-EID frame.
+     * This is the some of the Eddystone UUID(2 bytes), FrameType, AdvTxPower,
+     * EID Value
+     */
+    static const uint8_t EID_FRAME_LEN = 18;
+    static const uint8_t FRAME_LEN_OFFSET = 0;
+    static const uint8_t EDDYSTONE_UUID_LEN = 2;
+    static const uint8_t EID_DATA_OFFSET = 3;
+    static const uint8_t ADV_FRAME_OFFSET = 1;
+    static const uint8_t EID_VALUE_OFFSET = 5;
+    static const uint8_t EID_HEADER_LEN = 4;
+    static const uint8_t EID_TXPOWER_OFFSET = 4;
+    
+    /**
+     * AES128 ECB Encrypts a 16-byte input array with a key, to an output array
+     *
+     * @param[in] *key
+     *              The encryption key
+     * @param[in] *input
+     *              The input array
+     * @param[in] *output
+     *              The output array (contains the encrypted data)
+     */
+    void aes128Encrypt(uint8_t *key, uint8_t *input, uint8_t *output);
+ 
+};
+
+#endif  /* __EIDFRAME_H__ */