secure.h

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#ifndef BITCOIN_SUPPORT_ALLOCATORS_SECURE_H
#define BITCOIN_SUPPORT_ALLOCATORS_SECURE_H
 
#include <support/cleanse.h>
#include <support/lockedpool.h>
 
#include <memory>
#include <string>
 
//
// Allocator that locks its contents from being paged
// out of memory and clears its contents before deletion.
//
template <typename T> struct secure_allocator : public std::allocator<T> {
    using base = std::allocator<T>;
    using traits = std::allocator_traits<base>;
    using size_type = typename traits::size_type;
    using difference_type = typename traits::difference_type;
    using pointer = typename traits::pointer;
    using const_pointer = typename traits::const_pointer;
    using value_type = typename traits::value_type;
    secure_allocator() noexcept {}
    secure_allocator(const secure_allocator &a) noexcept : base(a) {}
    template <typename U>
    secure_allocator(const secure_allocator<U> &a) noexcept : base(a) {}
    ~secure_allocator() noexcept {}
    template <typename Other> struct rebind {
        typedef secure_allocator<Other> other;
    };
 
    T *allocate(std::size_t n, const void *hint = 0) {
        T *allocation = static_cast<T *>(
            LockedPoolManager::Instance().alloc(sizeof(T) * n));
        if (!allocation) {
            throw std::bad_alloc();
        }
        return allocation;
    }
 
    void deallocate(T *p, std::size_t n) {
        if (p != nullptr) {
            memory_cleanse(p, sizeof(T) * n);
        }
        LockedPoolManager::Instance().free(p);
    }
};
 
// This is exactly like std::string, but with a custom allocator.
typedef std::basic_string<char, std::char_traits<char>, secure_allocator<char>>
    SecureString;
 
#endif // BITCOIN_SUPPORT_ALLOCATORS_SECURE_H