CreateJWTToken uses golang-jwt package to generate jwt token and return that token as string.

HashPassword uses crypto package's GenerateFromPassword to convert plain text password into hash format.

SendEmail uses go's built in package net/smtp to send email to given address.

VerifyJWTToken takes token as parameter, verifies it and return userId and nil in case of token verified successfully and 0 and error if token verification failed.

VerifyPassword takes plain text password and corresponding hash as parameters and compare both by using crypto package's CompareHashAndPassword funciton.