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RHEncryptedDriver.h

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+// RHEncryptedDriver.h
+
+// Generic encryption layer that could use any driver
+// But will encrypt all data.
+// Requires the Arduinolibs/Crypto library:
+// https://github.com/rweather/arduinolibs
+//
+// Author: Philippe.Rochat'at'gmail.com
+// Contributed to the RadioHead project by the author
+// $Id: RHEncryptedDriver.h,v 1.4 2020/07/05 08:52:21 mikem Exp $
+
+#ifndef RHEncryptedDriver_h
+#define RHEncryptedDriver_h
+
+#include <RHGenericDriver.h>
+#if defined(RH_ENABLE_ENCRYPTION_MODULE) || defined(DOXYGEN)
+#include <BlockCipher.h>
+
+// Undef this if trailing 0 on each enrypted message is ok.
+// This defined means a first byte of the payload is used to encode content length
+// And the received message content is trimmed to this length
+#define STRICT_CONTENT_LEN  
+
+// Define this to allow encrypted content to span over 2 messages
+// STRICT_CONTENT_LEN and ALLOW_MULTIPLE_MSG aren't compatible !!!
+// With STRICT_CONTENT_LEN, receiver will try to extract length from every message !!!!
+//#define ALLOW_MULTIPLE_MSG  
+
+/////////////////////////////////////////////////////////////////////
+/// \class RHEncryptedDriver RHEncryptedDriver <RHEncryptedDriver.h>
+/// \brief Virtual Driver to encrypt/decrypt data. Can be used with any other RadioHead driver.
+///
+/// This driver acts as a wrapper for any other RadioHead driver, adding encryption and decryption of
+/// messages that are passed to and from the actual radio driver. Only the message payload is encrypted,
+/// and not the to/from address or flags. Any of the encryption ciphers supported by
+/// ArduinoLibs Cryptographic Library http://rweather.github.io/arduinolibs/crypto.html may be used.
+///
+/// For successful communications, both sender and receiver must use the same cipher and the same key.
+///
+/// In order to enable this module you must uncomment #define RH_ENABLE_ENCRYPTION_MODULE at the bottom of RadioHead.h
+/// But ensure you have installed the Crypto directory from arduinolibs first:
+/// http://rweather.github.io/arduinolibs/index.html
+
+class RHEncryptedDriver : public RHGenericDriver
+{
+public:
+    /// Constructor.
+    /// Adds a ciphering layer to messages sent and received by the actual transport driver.
+    /// \param[in] driver The RadioHead driver to use to transport messages.
+    /// \param[in] blockcipher The blockcipher (from arduinolibs) that crypt/decrypt data. Ensure that
+    /// the blockcipher has had its key set before sending or receiving messages.
+    RHEncryptedDriver(RHGenericDriver& driver, BlockCipher& blockcipher);
+
+    /// Calls the real driver's init()
+    /// \return The value returned from the driver init() method;
+    virtual bool init() { return _driver.init();};
+    
+    /// Tests whether a new message is available
+    /// from the Driver. 
+    /// On most drivers, this will also put the Driver into RHModeRx mode until
+    /// a message is actually received by the transport, when it wil be returned to RHModeIdle.
+    /// This can be called multiple times in a timeout loop
+    /// \return true if a new, complete, error-free uncollected message is available to be retreived by recv()
+    virtual bool available() { return _driver.available();};
+
+    /// Turns the receiver on if it not already on.
+    /// If there is a valid message available, copy it to buf and return true
+    /// else return false.
+    /// If a message is copied, *len is set to the length (Caution, 0 length messages are permitted).
+    /// You should be sure to call this function frequently enough to not miss any messages
+    /// It is recommended that you call it in your main loop.
+    /// \param[in] buf Location to copy the received message
+    /// \param[in,out] len Pointer to available space in buf. Set to the actual number of octets copied.
+    /// \return true if a valid message was copied to buf
+    virtual bool recv(uint8_t* buf, uint8_t* len);
+
+    /// Waits until any previous transmit packet is finished being transmitted with waitPacketSent().
+    /// Then optionally waits for Channel Activity Detection (CAD) 
+    /// to show the channnel is clear (if the radio supports CAD) by calling waitCAD().
+    /// Then loads a message into the transmitter and starts the transmitter. Note that a message length
+    /// of 0 is permitted. 
+    /// \param[in] data Array of data to be sent
+    /// \param[in] len Number of bytes of data to send
+    /// specify the maximum time in ms to wait. If 0 (the default) do not wait for CAD before transmitting.
+    /// \return true if the message length was valid and it was correctly queued for transmit. Return false
+    /// if CAD was requested and the CAD timeout timed out before clear channel was detected.
+    virtual bool send(const uint8_t* data, uint8_t len);
+
+    /// Returns the maximum message length 
+    /// available in this Driver, which depends on the maximum length supported by the underlying transport driver.
+    /// \return The maximum legal message length
+    virtual  uint8_t maxMessageLength();
+
+    /// Blocks until the transmitter 
+    /// is no longer transmitting.
+    virtual bool            waitPacketSent() { return _driver.waitPacketSent();} ;
+
+    /// Blocks until the transmitter is no longer transmitting.
+    /// or until the timeout occuers, whichever happens first
+    /// \param[in] timeout Maximum time to wait in milliseconds.
+    /// \return true if the radio completed transmission within the timeout period. False if it timed out.
+    virtual bool            waitPacketSent(uint16_t timeout) {return _driver.waitPacketSent(timeout);} ;
+
+    /// Starts the receiver and blocks until a received message is available or a timeout
+    /// \param[in] timeout Maximum time to wait in milliseconds.
+    /// \return true if a message is available
+    virtual bool            waitAvailableTimeout(uint16_t timeout) {return _driver.waitAvailableTimeout(timeout);};
+
+    /// Calls the waitCAD method in the driver
+    /// \return The return value from teh drivers waitCAD() method
+    virtual bool            waitCAD() { return _driver.waitCAD();};
+
+    /// Sets the Channel Activity Detection timeout in milliseconds to be used by waitCAD().
+    /// The default is 0, which means do not wait for CAD detection.
+    /// CAD detection depends on support for isChannelActive() by your particular radio.
+    void setCADTimeout(unsigned long cad_timeout) {_driver.setCADTimeout(cad_timeout);};
+
+    /// Determine if the currently selected radio channel is active.
+    /// This is expected to be subclassed by specific radios to implement their Channel Activity Detection
+    /// if supported. If the radio does not support CAD, returns true immediately. If a RadioHead radio 
+    /// supports isChannelActive() it will be documented in the radio specific documentation.
+    /// This is called automatically by waitCAD().
+    /// \return true if the radio-specific CAD (as returned by override of isChannelActive()) shows the
+    /// current radio channel as active, else false. If there is no radio-specific CAD, returns false.
+    virtual bool            isChannelActive() { return _driver.isChannelActive();};
+
+    /// Sets the address of this node. Defaults to 0xFF. Subclasses or the user may want to change this.
+    /// This will be used to test the adddress in incoming messages. In non-promiscuous mode,
+    /// only messages with a TO header the same as thisAddress or the broadcast addess (0xFF) will be accepted.
+    /// In promiscuous mode, all messages will be accepted regardless of the TO header.
+    /// In a conventional multinode system, all nodes will have a unique address 
+    /// (which you could store in EEPROM).
+    /// You would normally set the header FROM address to be the same as thisAddress (though you dont have to, 
+    /// allowing the possibilty of address spoofing).
+    /// \param[in] thisAddress The address of this node.
+    virtual void setThisAddress(uint8_t thisAddress) { _driver.setThisAddress(thisAddress);};
+
+    /// Sets the TO header to be sent in all subsequent messages
+    /// \param[in] to The new TO header value
+    virtual void           setHeaderTo(uint8_t to){ _driver.setHeaderTo(to);};
+
+    /// Sets the FROM header to be sent in all subsequent messages
+    /// \param[in] from The new FROM header value
+    virtual void           setHeaderFrom(uint8_t from){ _driver.setHeaderFrom(from);};
+
+    /// Sets the ID header to be sent in all subsequent messages
+    /// \param[in] id The new ID header value
+    virtual void           setHeaderId(uint8_t id){ _driver.setHeaderId(id);};
+
+    /// Sets and clears bits in the FLAGS header to be sent in all subsequent messages
+    /// First it clears he FLAGS according to the clear argument, then sets the flags according to the 
+    /// set argument. The default for clear always clears the application specific flags.
+    /// \param[in] set bitmask of bits to be set. Flags are cleared with the clear mask before being set.
+    /// \param[in] clear bitmask of flags to clear. Defaults to RH_FLAGS_APPLICATION_SPECIFIC
+    ///            which clears the application specific flags, resulting in new application specific flags
+    ///            identical to the set.
+    virtual void           setHeaderFlags(uint8_t set, uint8_t clear = RH_FLAGS_APPLICATION_SPECIFIC) { _driver.setHeaderFlags(set, clear);};
+
+    /// Tells the receiver to accept messages with any TO address, not just messages
+    /// addressed to thisAddress or the broadcast address
+    /// \param[in] promiscuous true if you wish to receive messages with any TO address
+    virtual void           setPromiscuous(bool promiscuous){ _driver.setPromiscuous(promiscuous);};
+
+    /// Returns the TO header of the last received message
+    /// \return The TO header
+    virtual uint8_t        headerTo() { return _driver.headerTo();};
+
+    /// Returns the FROM header of the last received message
+    /// \return The FROM header
+    virtual uint8_t        headerFrom() { return _driver.headerFrom();};
+
+    /// Returns the ID header of the last received message
+    /// \return The ID header
+    virtual uint8_t        headerId() { return _driver.headerId();};
+
+    /// Returns the FLAGS header of the last received message
+    /// \return The FLAGS header
+    virtual uint8_t        headerFlags() { return _driver.headerFlags();};
+
+    /// Returns the most recent RSSI (Receiver Signal Strength Indicator).
+    /// Usually it is the RSSI of the last received message, which is measured when the preamble is received.
+    /// If you called readRssi() more recently, it will return that more recent value.
+    /// \return The most recent RSSI measurement in dBm.
+    int16_t        lastRssi() { return _driver.lastRssi();};
+
+    /// Returns the operating mode of the library.
+    /// \return the current mode, one of RF69_MODE_*
+    RHMode          mode() { return _driver.mode();};
+
+    /// Sets the operating mode of the transport.
+    void            setMode(RHMode mode) { _driver.setMode(mode);};
+
+    /// Sets the transport hardware into low-power sleep mode
+    /// (if supported). May be overridden by specific drivers to initialte sleep mode.
+    /// If successful, the transport will stay in sleep mode until woken by 
+    /// changing mode it idle, transmit or receive (eg by calling send(), recv(), available() etc)
+    /// \return true if sleep mode is supported by transport hardware and the RadioHead driver, and if sleep mode
+    ///         was successfully entered. If sleep mode is not suported, return false.
+    virtual bool    sleep() { return _driver.sleep();};
+
+    /// Returns the count of the number of bad received packets (ie packets with bad lengths, checksum etc)
+    /// which were rejected and not delivered to the application.
+    /// Caution: not all drivers can correctly report this count. Some underlying hardware only report
+    /// good packets.
+    /// \return The number of bad packets received.
+    virtual uint16_t       rxBad() { return _driver.rxBad();};
+
+    /// Returns the count of the number of 
+    /// good received packets
+    /// \return The number of good packets received.
+    virtual uint16_t       rxGood() { return _driver.rxGood();};
+
+    /// Returns the count of the number of 
+    /// packets successfully transmitted (though not necessarily received by the destination)
+    /// \return The number of packets successfully transmitted
+    virtual uint16_t       txGood() { return _driver.txGood();};
+
+private:
+    /// The underlying transport river we are to use
+    RHGenericDriver&        _driver;
+    
+    /// The CipherBlock we are to use for encrypting/decrypting
+    BlockCipher&	    _blockcipher;
+    
+    /// Struct for with buffers for ciphering
+    typedef struct
+    {
+	size_t  blockSize    = 0;
+	uint8_t *inputBlock  = NULL;
+	//uint8_t *outputBlock = NULL;		
+    } CipherBlocks;
+    
+    CipherBlocks            _cipheringBlocks;
+    
+    /// Buffer to store encrypted/decrypted message
+    uint8_t*                _buffer;
+};
+
+/// @example nrf24_encrypted_client.ino
+/// @example nrf24_encrypted_server.ino
+/// @example rf95_encrypted_client.ino
+/// @example rf95_encrypted_server.ino
+/// @example serial_encrypted_reliable_datagram_client.ino
+/// @example serial_encrypted_reliable_datagram_server.ino
+
+
+#else // RH_ENABLE_ENCRYPTION_MODULE
+#error "You have included RHEncryptedDriver.h, but not enabled RH_ENABLE_ENCRYPTION_MODULE in RadioHead.h"
+#endif
+
+#endif