Of course, you'll have to use whatever the third-party API uses, which includes Gravatar, but don't use it for anything under your control. Replace with: - BL

Of course, you'll have to use whatever the third-party API uses, which includes Gravatar, but don't use it for anything under your control. Replace with: - BLAKE2 if you need a fast cryptographic hash function (e.g. for hashing file contents) - SHA512 (or SHA256, or SHA-3) if you want a standard cryptographic hash function that is available in your programming language libraries (Speaking of Gravatar, their use of md5(email) or even more secure hash function won't help protect email addresses against dedicated attackers, as it's easy to iterate over billions of them in seconds, just like in the stories about password cracking you hear, but it works as a simple anti-spam measure.)