Failed a technical interview for a Blockchain Security Engineer role — need help with cryptography prep

I recently gave a technical interview for a Blockchain Security Engineer position and didn’t make it through. Most of the questions were around cryptography, and I realized that’s where my understanding isn’t strong enough.

They asked about hash functions, digital signatures, elliptic curve cryptography, and key management — but the depth of the questions were out of my knowledge to answer confidently.

For those who’ve cleared similar interviews, what are the key cryptography and security concepts I should focus on while preparing?
Any good learning path or resource list you’d recommend for improving technical preparation in this area?