Adding to this, before "crypto" became a household term that meant, roughly, "blockchain stuff" it was instead a general term for "cryptography". It's what is (perhaps was) meant when people say not to "roll your own crypto"[0] because it's so easy to get wrong.
[0] Since 2021 this phrase has been expanded to "roll your own crypto scam" and it's only used as an ethical statement. Don't "roll your own crypto scam" because it's wrong. (Okay, maybe this part is just a joke and people don't really say that. It's hard to say for sure.)
https://www.coursera.org/learn/crypto (note even though it says crypto it is NOT related to blockchain crypto).