random.h

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/*
BSD 3-Clause License
 
Copyright (c) 2022, Stable Cloud Computing, Inc.
 
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
 
1. Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.
 
2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.
 
3. Neither the name of the copyright holder nor the names of its
   contributors may be used to endorse or promote products derived from
   this software without specific prior written permission.
 
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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*/
#ifndef _SCC_CRYPTO_RANDOM_H
#define _SCC_CRYPTO_RANDOM_H
 
#include <climits>
#include <string>
 
namespace scc::crypto {
 
class RandomEngine
{
public:
    RandomEngine() {}
 
    static void* ctx();
 
    static void lock();
    
    static void unlock();
 
    static void random_seed();
 
    static void seed(const void *, int len);
    static void seed(const std::string& buf)
    {
        seed((void*)buf.data(), buf.size());
    }
 
    static void rand_bytes(void *, int len);
    static uint32_t rand_uint32()
    {
        uint32_t r;
        rand_bytes(&r, sizeof(uint32_t));
        return r;
    }
    static int32_t rand_int32()
    {
        int32_t r;
        rand_bytes(&r, sizeof(int32_t));
        return r;
    }
    static uint64_t rand_uint64()
    {
        uint64_t r;
        rand_bytes(&r, sizeof(uint64_t));
        return r;
    }
    static int64_t rand_int64()
    {
        int64_t r;
        rand_bytes(&r, sizeof(int64_t));
        return r;
    }
 
    typedef int result_type;
    int operator ()()
    {
        return rand_uint32();
    }
    constexpr int min() { return 0; }
    constexpr int max() { return UINT_MAX; }
};
 
class RandomEngineLocker
{
    bool m_lk;
public:
    RandomEngineLocker() : m_lk(false)
    {
        lock();
    }
    ~RandomEngineLocker()
    {
        unlock();
    }
    void lock()
    {
        if (!m_lk)
        {
            RandomEngine::lock();
            m_lk = true;
        }
    }
    void unlock()
    {
        if (m_lk)
        {
            RandomEngine::unlock();
            m_lk = false;
        }
    }
};
}   // namespace
 
#endif