Implement in Go lang AES encryption mode CBC with providing thepackages name for Go lang. You can implement AES-ECB Mode (thebasic AES) from crypto/aes package and crypto/cipher.Block. You canalso get the SHA-256 hash function from crypto/sha256. You can getthe secure random numbers generator from crypto/rand package.However, the you will implement both CBC mode and HMAC fromscratch. You are NOT allowed to use any libraries or packages toimplement these two things for you. You are permitted to use anypackages for anything else provided that it is part of the languageitself.
I will expect that your code is run as follows:
encrypt-auth <mode> -k
OR
PayPal Gateway not configured
OR
PayPal Gateway not configured