There were two common cryptography misconceptions that we unlearned in school, and this post is about the first one we learned about. (And Cryptonomicon helped with this one too.) We hear a lot about how “strong” encryption is. That our files would take bazillion years to decrypt via brute force or that our Bitcoin account […]

Let’s say you have some private-key (symmetric-key) encryption scheme. It takes a key and a message, and outputs a ciphertext. Nobody without the key can decrypt the message using the decrypter. Is that secure? Not if it’s deterministic.