Cryptography is the easy part of cryptography. You can learn it as a high school student interested in programming and mathematics. I did that in the late 90s, first from Applied Cryptography and then from more advanced books. I implemented a few algorithms back then, and I also wrote a password manager I used until I learned about the existence of better third-party tools.
The real issue is that cryptography is an adversarial field. The human / systems / software aspects are the hard parts. The crypto you wrote yourself doesn't fail because you got the crypto wrong but because your adversary cheats. (I eventually lost interest in cryptography due to the adversarial nature.)
The real issue is that cryptography is an adversarial field. The human / systems / software aspects are the hard parts. The crypto you wrote yourself doesn't fail because you got the crypto wrong but because your adversary cheats. (I eventually lost interest in cryptography due to the adversarial nature.)