Decrypt text using AES256 GCM in golang

decrypt.go

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
 	"encoding/hex"
	"os"
)

// Decrypt will return the original value of the encrypted string
func Decrypt(encryptedKey []byte) ([]byte, error) {
	secretKey := getSecret()

	block, err := aes.NewCipher(secretKey)

	if err != nil {
		return nil, err
	}

	aesgcm, err := cipher.NewGCM(block)
	if err != nil {
		return nil, err
	}

	if len(encryptedKey) < aesgcm.NonceSize() {
		// worth panicking when encrypted key is bad
		panic("Malformed encrypted key")
	}

	return aesgcm.Open(
		nil,
		encryptedKey[:aesgcm.NonceSize()],
		encryptedKey[aesgcm.NonceSize():],
		nil,
	)
}

func getSecret() []byte {
	secret := os.Getenv("SECRET")
	if secret == "" {
		panic("Error: Must provide a secret key under env variable SECRET")
	}

	secretbite, err := hex.DecodeString(secret)

	if err != nil {
		// probably malform secret, panic out
		panic(err)
	}

	return secretbite
}