In cryptography an oracle is someone or something you can query that returns an answer that you cannot know from just the math. It doesn't have to be an API. S

In cryptography an oracle is someone or something you can query that returns an answer that you cannot know from just the math. It doesn't have to be an API. Side channel attacks can provide unintentional oracles. For example, if you have a password checking function that takes longer to return a false result for "close" inputs, then it leaks information that can be used to crack passwords (simple O(n) string comparison would be an example) https://en.wikipedia.org/wiki/Oracle_attack https://en.wikipedia.org/wiki/Oracle_attack