Introduce stronger types instead of relying on Strings that are assumed to be HEX

[amschel99]

The current design of the crypto library API relies extensively on string representations of hexadecimal values. While having a FromStr implementation for hex strings may suffice for some use cases, basing the entire API interface on strings assumed to be hex is suboptimal.
To address these concerns, refactor the library to provide dedicated types for hexadecimal values, along with parsing and formatting methods tailored to these types.