crypto Package

Go ships a family of cryptographic packages under the crypto/ import path: hash functions, message authentication, primitives for symmetric and public-key crypto, a secure random source, and a few small helpers like constant-time comparison. This chapter is an overview of the parts an everyday e-commerce backend reaches for most often: hashing order data, signing download links, verifying notifications from a payment provider, storing customer passwords, and comparing secrets without leaking timing information. The cryptographic protocols built on top (TLS, AES-GCM, RSA signing) get their own dedicated treatment elsewhere and aren't covered here.