Wouldn't one just use OpenSSL?
I just looked for something simple like: auto sha = sha256_digest("blah");
And I couldn't find that easily :( I found some library, but I had been modificating that about two hours.FYI - I search for d language <something>.
But, please, ask me. Is it hard to add some string to your site? Just add string - that will do live easier for many D2 users.