code: func AESEncryptWithCFB(cryptStr, key []byte, iv []byte) ([]byte, error) {
  	cb, err := aes.NewCipher(key)
  	if err != nil {
  		return nil, err
  	}
  	cfb := cipher.NewCFBEncrypter(cb, iv)
  	crypted := make([]byte, len(cryptStr))
  	cfb.XORKeyStream(crypted, cryptStr)
  	return crypted, nil
  }
docs: // AESEncryptWithCFB decrypts data using AES with CFB mode.