This is fascinating but being neither a CS nor Maths graduate I'm having trouble following the maths from the moment modulo operations are introduced. Would so

This is fascinating but being neither a CS nor Maths graduate I'm having trouble following the maths from the moment modulo operations are introduced. Would someone be able to suggest a self-learning resource (book, app, ...) that goes into cryptography and the required maths but doesn't demand too much pre-knowledge? Thanks in advance!