asit-dhal

How to setup your own CA with OpenSSL

For educational reasons I've decided to create my own CA. Here is what I learned.

First things first

Lets get some context first.

asit-dhal

int main()
{
    B b(1, 'a', 'b', 'e');
    auto& [e1, e2, e3, e4] =b;
    e1 = 100;
    e2 = 'k';
    e3 = 'l';
    e4 = 'm';
    assert(100 == b.a);
    assert('k' == b.c);

asit-dhal

template<std::size_t idx> decltype(auto) get(B &b)
{
    static_assert (idx < 4);
    if constexpr (idx == 0) {
        return static_cast<int&>(b.a);
    } else if constexpr (idx == 1) {
        return static_cast<char&>(b.c);
    } else if constexpr (idx == 2) {
        return static_cast<char&>(b.d);
    } else {

asit-dhal

int main()
{
    B b(1, 'a', 'b', 'e');
    auto [e1, e2, e3, e4] = b;
    assert(e1 == b.a);
    assert(e2 == b.c);
    assert(e3 == b.d);
    assert(e4 == b.e);
}

asit-dhal

template<std::size_t idx> auto get(const B &b)
{
    static_assert (idx < 4);
    if constexpr (idx == 0) {
        return b.a;
    } else if constexpr (idx == 1) {
        return b.c;
    } else if constexpr (idx == 2) {
        return b.d;
    } else {

asit-dhal

template<std::size_t> auto get(const B&);
template<> auto get<0>(const B &b) { return b.a; }
template<> auto get<1>(const B &b) { return b.c; }
template<> auto get<2>(const B &b) { return b.d; }
template<> auto get<3>(const B &b) { return b.e; }

asit-dhal

template<>
struct std::tuple_element<0, B>
{
    using type = int;
};

template<std::size_t idx>
struct std::tuple_element<idx, B>
{
    using type = char;

asit-dhal

template<>
struct std::tuple_size<B>
{
    static constexpr int value = 4;
};

asit-dhal

struct A {
    explicit A(int a) : a(a) {}
    int a;
};

struct B : public A {
    B(int a, char c, char d, char e) : A(a), c(c), d(d), e(e) {}
    char c;
    char d;
    char e;

asit-dhal

struct RetVal
{
    int x;
    int& y;
    const int& z;
};

RetVal doSomething(int& a, const int &b) {
    return {10, a, b};
}