secure_vector.h

// Copyright (c) 2014-2026 Savoir-faire Linux Inc.
// SPDX-License-Identifier: MIT
#pragma once
 
#include <vector>
#include <random>
 
namespace dht {
namespace crypto {
 
template<class T>
class secure_vector
{
public:
    secure_vector() {}
    secure_vector(secure_vector<T> const&) = default;
    secure_vector(secure_vector<T>&&) = default;
    explicit secure_vector(unsigned size)
        : data_(size)
    {}
    explicit secure_vector(unsigned size, T _item)
        : data_(size, _item)
    {}
    explicit secure_vector(const std::vector<T>& c)
        : data_(c)
    {}
    secure_vector(std::vector<T>&& c)
        : data_(std::move(c))
    {}
    ~secure_vector() { clean(); }
 
    static secure_vector<T> getRandom(size_t size)
    {
        secure_vector<T> ret(size);
        std::random_device rdev;
#ifdef _WIN32
        std::uniform_int_distribution<int> rand_byte {0, std::numeric_limits<uint8_t>::max()};
#else
        std::uniform_int_distribution<uint8_t> rand_byte;
#endif
        std::generate_n((uint8_t*) ret.data_.data(), ret.size() * sizeof(T), std::bind(rand_byte, std::ref(rdev)));
        return ret;
    }
    secure_vector<T>& operator=(const secure_vector<T>& c)
    {
        if (&c == this)
            return *this;
        clean();
        data_ = c.data_;
        return *this;
    }
    secure_vector<T>& operator=(secure_vector<T>&& c)
    {
        if (&c == this)
            return *this;
        clean();
        data_ = std::move(c.data_);
        return *this;
    }
    secure_vector<T>& operator=(std::vector<T>&& c)
    {
        clean();
        data_ = std::move(c);
        return *this;
    }
    std::vector<T>& writable()
    {
        clean();
        return data_;
    }
    const std::vector<T>& makeInsecure() const { return data_; }
    const uint8_t* data() const { return data_.data(); }
 
    void clean() { clean(data_.begin(), data_.end()); }
 
    void clear()
    {
        clean();
        data_.clear();
    }
 
    size_t size() const { return data_.size(); }
    bool empty() const { return data_.empty(); }
 
    void swap(secure_vector<T>& other) { data_.swap(other.data_); }
    void resize(size_t s)
    {
        if (s == data_.size())
            return;
        if (s < data_.size()) {
            // shrink
            clean(data_.begin() + s, data_.end());
            data_.resize(s);
        } else {
            // grow
            auto data = std::move(data_); // move protected data
            clear();
            data_.resize(s);
            std::copy(data.begin(), data.end(), data_.begin());
            clean(data.begin(), data.end());
        }
    }
 
private:
    static void clean(const typename std::vector<T>::iterator& i, const typename std::vector<T>::iterator& j)
    {
        volatile uint8_t* b = reinterpret_cast<uint8_t*>(&*i);
        volatile uint8_t* e = reinterpret_cast<uint8_t*>(&*j);
        std::fill(b, e, 0);
    }
 
    std::vector<T> data_;
};
 
using SecureBlob = secure_vector<uint8_t>;
 
} // namespace crypto
} // namespace dht