Dan Boneh is great - his lecture series on Youtube is wonderful.
A book I enjoyed a lot, that straddles the line between approachable and theoretical with a focus on implementation, is Serious Cryptography by Jean-Philippe Aumasson (one of the people behind blake2/3, amongst other things): https://nostarch.com/seriouscrypto
A book I enjoyed a lot, that straddles the line between approachable and theoretical with a focus on implementation, is Serious Cryptography by Jean-Philippe Aumasson (one of the people behind blake2/3, amongst other things): https://nostarch.com/seriouscrypto