Maxim Integrated / Mbed OS MAXREFDES155#

DeepCover Embedded Security in IoT: Public-key Secured Data Paths

Dependencies:   MaximInterface

The MAXREFDES155# is an internet-of-things (IoT) embedded-security reference design, built to authenticate and control a sensing node using elliptic-curve-based public-key cryptography with control and notification from a web server.

The hardware includes an ARM® mbed™ shield and attached sensor endpoint. The shield contains a DS2476 DeepCover® ECDSA/SHA-2 coprocessor, Wifi communication, LCD push-button controls, and status LEDs. The sensor endpoint is attached to the shield using a 300mm cable and contains a DS28C36 DeepCover ECDSA/SHA-2 authenticator, IR-thermal sensor, and aiming laser for the IR sensor. The MAXREFDES155# is equipped with a standard Arduino® form-factor shield connector for immediate testing using an mbed board such as the MAX32600MBED#. The combination of these two devices represent an IoT device. Communication to the web server is accomplished with the shield Wifi circuitry. Communication from the shield to the attached sensor module is accomplished over I2C . The sensor module represents an IoT endpoint that generates small data with a requirement for message authenticity/integrity and secure on/off operational control.

The design is hierarchical with each mbed platform and shield communicating data from the sensor node to a web server that maintains a centralized log and dispatches notifications as necessary. The simplicity of this design enables rapid integration into any star-topology IoT network to provide security with the low overhead and cost provided by the ECDSA-P256 asymmetric-key and SHA-256 symmetric-key algorithms.

More information about the MAXREFDES155# is available on the Maxim Integrated website.

xternal/rapidjson/filewritestream.h

Committer:
IanBenzMaxim
Date:
2019-10-03
Revision:
16:a004191a79ab
Parent:
rapidjson/filewritestream.h@ 0:33d4e66780c0

File content as of revision 16:a004191a79ab:

// Tencent is pleased to support the open source community by making RapidJSON available.
// 
// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
//
// Licensed under the MIT License (the "License"); you may not use this file except
// in compliance with the License. You may obtain a copy of the License at
//
// http://opensource.org/licenses/MIT
//
// 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 RAPIDJSON_FILEWRITESTREAM_H_
#define RAPIDJSON_FILEWRITESTREAM_H_

#include "stream.h"
#include <cstdio>

#ifdef __clang__
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(unreachable-code)
#endif

RAPIDJSON_NAMESPACE_BEGIN

//! Wrapper of C file stream for input using fread().
/*!
    \note implements Stream concept
*/
class FileWriteStream {
public:
    typedef char Ch;    //!< Character type. Only support char.

    FileWriteStream(std::FILE* fp, char* buffer, size_t bufferSize) : fp_(fp), buffer_(buffer), bufferEnd_(buffer + bufferSize), current_(buffer_) { 
        RAPIDJSON_ASSERT(fp_ != 0);
    }

    void Put(char c) { 
        if (current_ >= bufferEnd_)
            Flush();

        *current_++ = c;
    }

    void PutN(char c, size_t n) {
        size_t avail = static_cast<size_t>(bufferEnd_ - current_);
        while (n > avail) {
            std::memset(current_, c, avail);
            current_ += avail;
            Flush();
            n -= avail;
            avail = static_cast<size_t>(bufferEnd_ - current_);
        }

        if (n > 0) {
            std::memset(current_, c, n);
            current_ += n;
        }
    }

    void Flush() {
        if (current_ != buffer_) {
            size_t result = fwrite(buffer_, 1, static_cast<size_t>(current_ - buffer_), fp_);
            if (result < static_cast<size_t>(current_ - buffer_)) {
                // failure deliberately ignored at this time
                // added to avoid warn_unused_result build errors
            }
            current_ = buffer_;
        }
    }

    // Not implemented
    char Peek() const { RAPIDJSON_ASSERT(false); return 0; }
    char Take() { RAPIDJSON_ASSERT(false); return 0; }
    size_t Tell() const { RAPIDJSON_ASSERT(false); return 0; }
    char* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
    size_t PutEnd(char*) { RAPIDJSON_ASSERT(false); return 0; }

private:
    // Prohibit copy constructor & assignment operator.
    FileWriteStream(const FileWriteStream&);
    FileWriteStream& operator=(const FileWriteStream&);

    std::FILE* fp_;
    char *buffer_;
    char *bufferEnd_;
    char *current_;
};

//! Implement specialized version of PutN() with memset() for better performance.
template<>
inline void PutN(FileWriteStream& stream, char c, size_t n) {
    stream.PutN(c, n);
}

RAPIDJSON_NAMESPACE_END

#ifdef __clang__
RAPIDJSON_DIAG_POP
#endif

#endif // RAPIDJSON_FILESTREAM_H_