PyCryptodome AES, 'EcbMode' object has no attribute 'encrypt_and_digest'

Question

I am using Pycharm Text Editor and PyCryptodome Library for encryption of message using Advanced Encryption Standard (AES). It is also one of the majorly used Symmetric Encryption Algorithm. My code of AES Encryption was stated below:

from Crypto.Cipher import AES
key = os.urandom(16)
cipher = AES.new(key, AES.MODE_ECB)
ciphertext, tag = cipher.encrypt_and_digest(message)

And I am encountering the error:-

AttributeError: 'EcbMode' object has no attribute 'encrypt_and_digest

at line:-

ciphertext, tag = cipher.encrypt_and_digest(message)

I have tried uninstalling the module a couple of times but the error persists. Pycharm does not mark the line with red underscores and I can use ctrl-click to go into the source and see that the encrypt_and_digest() function exists.

My question is:-

Why can't the code go through the compiler? Is there another module in python that I can use to perform AES encryption?

score 2 · Answer 1 · answered Apr 19 '21 at 10:52

2

If you read the documentation you will see that encrypt_and_digest() is only supported by the modern modes:

MODE_CCM
MODE_EAX
MODE_GCM
MODE_SIV
MODE_OCB

ECB mode really shouldn't be used for anything as it is not semantically secure.

answered Apr 19 '21 at 10:52

Iridium

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Jay Patel · Accepted Answer · 2021-04-19T13:23:07.117

From Error we can see that encrypt_and_digest() attribute is not available in ECB (Electronic Code Book) Mode of AES Encryption. So, there are two Solution for your query let's have a look at one by one:-

1. By Changing Mode:-

By Changing mode to modern modes we can use encrypt_and_digest() module. Basically encrypt_and_digest() module is combination of encrypt() and digest() Module.

encrypt():- This module used to Encrypt your Message
digest():- This module used to Generate MAC Tag of Message

# List of 'Modern Modes' was given below:-
1. MODE_EAX
2. MODE_CCM
3. MODE_SIV
4. MODE_GCM
5. MODE_OCB

Code for the given Scenario Using EAX Mode was stated below:-

# Import all the Important Libraries
from Crypto.Cipher import AES
import os

# 'pad_message()' function declaration for padding purpose.
# Because 'message' length should be always multiple of '16'
def pad_message(message):
  while len(message) % 16 != 0:
    message = message + " "
  return message

# Initialization of 'Key' and 'Message'
key = os.urandom(16)
message = input("Enter your Message for AES Encryption:- ")

# If the length of the message is not multiple of '16' then pad it
message = pad_message(message)

# Print Message, Key and Length of Message before Encryption Process
print("\nMessage:-", message)
print("Key:-", key)
print("Length of the Message:-", len(message))

# Declare New module for AES Encryption in 'EAX' Mode
cipher = AES.new(key, AES.MODE_EAX)

# Encrypt 'Message' and Generate 'MAC Tag' Using 'encrypt_and_digest()' method
cipher_text, mac_tag = cipher.encrypt_and_digest(message.encode('utf-8'))

# Print Encrypted Message 
print("\nEncryption of Message Using AES:-", cipher_text)
print("MAC Tag of our Encrypted Message is:-", mac_tag)

# Output of Above Code:-
Enter your Message for AES Encryption:- Stack Overflow

Message:- Stack Overflow  
Key:- b'\xf1\x9a\xc1\x12\xdcI7\xc8\xe4\xcf\x1e5\xe4\x93i\xc4'
Length of the Message:- 16

Encryption of Message Using AES:- b'\x97\x0e+\xcb^\x82\xeelhs2_\x90m\x1c+'
MAC Tag of our Encrypted Message is:- b'c!\xb2\xf4\x82\xceT3\x0cM1\x04\x87(y?'

2. Without Changing Mode:-

If you want to Encrypt Using ECB (Electronic Code Book) Mode. then we can Use encrypt() and hex() module.

Code for the given Scenario Using ECB Mode was stated below:-

# Import all the Important Libraries
from Crypto.Cipher import AES
import os

# 'pad_message()' function declaration for padding purpose.
# Because 'message' length should be always multiple of '16'
def pad_message(message):
  while len(message) % 16 != 0:
    message = message + " "
  return message

# Initialization of 'Key' and 'Message'
key = os.urandom(16)
message = input("Enter your Message for AES Encryption:- ")

# If the length of the message is not multiple of '16' then pad it
message = pad_message(message)

# Print Message, Key and Length of Message before Encryption Process
print("\nMessage:-", message)
print("Key:-", key)
print("Length of the Message:-", len(message))

# Declare New module for AES Encryption in 'ECB (Electronic Codebook)' Mode
cipher = AES.new(key, AES.MODE_ECB)

# Encrypt 'Message'
cipher_text  = cipher.encrypt(message.encode('utf-8'))

# Print Encrypted Message 
print("\nEncryption of Message Using AES:-", cipher_text)
print("Hex of Cipher Text:-", cipher_text.hex())

# Verify by decrypting Cipher Text whether you are recieving same message or not
decrypted_message = cipher.decrypt(cipher_text)
print("\nDecryption of Cipher Text Using AES:-", decrypted_message)

# Output of Above Code:-
Enter your Message for AES Encryption:- Stack Overflow

Message:- Stack Overflow  
Key:- b'\x94\x88o\xf0\x8f\xbe\xec\x0e\x1e\xdf\x06A\xdf<\xbe\xe3'
Length of the Message:- 16

Encryption of Message Using AES:- b'\xf6c)\xee\xea\x13\xdcX\x9c\x06E\x82~{c\xc6'
Hex of Cipher Text:- f66329eeea13dc589c0645827e7b63c6

The decryption of Cipher Text Using AES:- b'Stack Overflow

Hope this Solution helps you.

Any differences in security when it comes to "NOTE:- hex() and digest() are not same. But it was similar because MAC Tag Generated by digest() was in hex Format." in your opinion? — Maarten Bodewes, Apr 19 '21 at 13:17
Sorry, It was my mistake. `hex()` and `digest()` are totally different modules in terms of Security. Thank you for the spotting light on this mistake. I have updated my Post. Does there is any other mistake? — Jay Patel, Apr 19 '21 at 13:27

PyCryptodome AES, 'EcbMode' object has no attribute 'encrypt_and_digest'

2 Answers2