CheckPasswordHash compares the given password with the hash.

GenerateJWT generates a new JWT token with the given userID, tokenSecret and expiresIn.

GenerateRefreshToken generates a random 32-byte token and returns it as a hex-encoded string.

GetBearerToken extracts the Bearer token from the Authorization header.

HashPassword hashes the given password.

ValidateJWT validates the given JWT token with the tokenSecret.