SecureBuffer.cpp

#include <unknwn.h>
#include "winrt/Windows.Storage.Streams.h"

using namespace winrt;
using namespace Windows::Foundation;
using namespace Windows::Storage::Streams;

struct __declspec(uuid("905a0fef-bc53-11df-8c49-001e4fc686da")) IBufferByteAccess : ::IUnknown
{
    virtual HRESULT __stdcall Buffer(uint8_t** value) noexcept = 0;
};

struct SecureBuffer : implements<SecureBuffer, IBuffer, IBufferByteAccess, IClosable>
{
    std::vector<uint8_t> m_buffer;
    uint32_t m_length{};

    SecureBuffer(uint32_t size) :
        m_buffer(size)
    {
    }

    ~SecureBuffer() noexcept
    {
        Close();
    }

    void Close() noexcept
    {
        SecureZeroMemory(m_buffer.data(), m_buffer.size());
    }

    uint32_t Capacity() const noexcept
    {
        return static_cast<uint32_t>(m_buffer.size());
    }

    uint32_t Length() const noexcept
    {
        return m_length;
    }

    void Length(uint32_t value)
    {
        if (value > m_buffer.size())
        {
            throw hresult_invalid_argument();
        }

        m_length = value;
    }

    HRESULT __stdcall Buffer(uint8_t** value) noexcept final
    {
        *value = m_buffer.data();
        return S_OK;
    }
};