How Can You Securely Clear Sensitive Data Stored in a `std::string`?

Secure Clearing of Sensitive Data in std::string

Storing sensitive data, such as passwords, in memory requires secure clearing mechanisms to prevent potential memory leaks. While char* arrays offer the SecureZeroMemory API for this purpose, the use of std::string raises the question of implementing a similar solution.

Challenges with std::string

One attempt was made to create a custom allocator that securely zeros out memory upon deallocation:

<code class="cpp">namespace secure {
  template <class T> class allocator : public std::allocator<T> {...}
}</code>

However, it was discovered that this allocator is not always invoked for small strings, potentially leaving sensitive data exposed.

Solution: Avoid Using std::string for Sensitive Data

The conclusion is that std::string, as currently defined, is not suitable for storing sensitive data. Custom implementations or alternative data structures should be considered for this specific purpose.

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