Unable to import module 'lambda_function': No module named 'Crypto'

Question

I have following python lambda function

lambda_function.py

from Crypto.Cipher import AES
from Crypto.Util.Padding import pad,unpad
import base64

#CBC with Fix IV

data = 'random text to be encrypted decrypted'
key = 'xxx' #16 char for AES128

#FIX IV
iv =  'yyy'.encode('utf-8') #16 char for AES128

def encrypt(data,key,iv):
        data= pad(data.encode(),16)
        cipher = AES.new(key.encode('utf-8'),AES.MODE_CBC,iv)
        return base64.b64encode(cipher.encrypt(data))

def decrypt(enc,key,iv):
        enc = base64.b64decode(enc)
        cipher = AES.new(key.encode('utf-8'), AES.MODE_CBC, iv)
        return unpad(cipher.decrypt(enc),16)

encrypted = encrypt(data,key,iv)
print('encrypted CBC base64 : ',encrypted.decode("utf-8", "ignore"))

decrypted = decrypt(encrypted,key,iv)
print('decrypted data: ', decrypted.decode("utf-8", "ignore"))

def lambda_handler(event, context):
    encrypt(data, key, iv)

I created a lambda function using runtime python 3.12 and created a layer called custom_encrypt_decrypt and added this layer to the lambda as shown below,

When I try to execute the lambda, it throws error,

"Unable to import module 'lambda_function': No module named 'Crypto'"

---

Firstly, I found that I have to use pycryptodome python library.

How I uploaded this library to lambda

1. in my local computer I added the library,

   pip install pycryptodome

It added these two folders in my local

2. I selected both the folders and created a .zip folder.
3. uploaded zip folder to custom_encrypt_decrypt layer (and layer is already attached to lambda) - Note: pointing to right layer version.
4. Executed lambda again and getting the same error again n again.

---

NOTE: If I run this python code locally, it works using same pycryptodome library!

---

Updates:

There is some serious problem and I don't know what is wrong.

I reduced my lambda code to below,

import json
from Crypto.Cipher import AES
from Crypto.Util.Padding import pad,unpad
import base64

def lambda_handler(event, context):
    # TODO implement
    return {
        'statusCode': 200,
        'body': json.dumps('Hello from Lambda!')
    }

and followed steps suggested by @Roronoa Zoro (for windwos) and now I get below errors

{
  "errorMessage": "Cannot load native module 'Crypto.Cipher._raw_ecb': Not found '_raw_ecb.cpython-312-x86_64-linux-gnu.so', Not found '_raw_ecb.abi3.so', Not found '_raw_ecb.so'",
  "errorType": "OSError",
  "requestId": "",
  "stackTrace": [
    "  File \"/var/lang/lib/python3.12/importlib/__init__.py\", line 90, in import_module\n    return _bootstrap._gcd_import(name[level:], package, level)\n",
    "  File \"<frozen importlib._bootstrap>\", line 1381, in _gcd_import\n",
    "  File \"<frozen importlib._bootstrap>\", line 1354, in _find_and_load\n",
    "  File \"<frozen importlib._bootstrap>\", line 1325, in _find_and_load_unlocked\n",
    "  File \"<frozen importlib._bootstrap>\", line 929, in _load_unlocked\n",
    "  File \"<frozen importlib._bootstrap_external>\", line 994, in exec_module\n",
    "  File \"<frozen importlib._bootstrap>\", line 488, in _call_with_frames_removed\n",
    "  File \"/var/task/lambda_function.py\", line 2, in <module>\n    from Crypto.Cipher import AES\n",
    "  File \"/opt/python/Crypto/Cipher/__init__.py\", line 27, in <module>\n    from Crypto.Cipher._mode_ecb import _create_ecb_cipher\n",
    "  File \"/opt/python/Crypto/Cipher/_mode_ecb.py\", line 35, in <module>\n    raw_ecb_lib = load_pycryptodome_raw_lib(\"Crypto.Cipher._raw_ecb\", \"\"\"\n",
    "  File \"/opt/python/Crypto/Util/_raw_api.py\", line 315, in load_pycryptodome_raw_lib\n    raise OSError(\"Cannot load native module '%s': %s\" % (name, \", \".join(attempts)))\n"
  ]
}

Answer 1

I was facing the same issue after some troubleshooting, I was able to fix the issue.

• Check the python version in local machine and Lambda (It should be similar) as few packages are not imported properly when different version is there.

Create Zip file in below mentioned path:

• Create Virtual environment for python3.

python3 -m venv venv
source venv/bin/activate

• Create a directory with name "python"

mkdir python
cd python

• Install you packages in this folder.

pip3 install pycryptodome -t .

• Once installed Check the packages.
• Create ZIP file for python directory

cd .. 
zip -r deployment_name.zip python

• Now you can upload the .zip file to you AWS Lambda Layer.

Make sure the ZIP file is created for all folder available in python folder Don't miss out any files or folders it may be our main package may be dependent on it.

---

For Windows

• Using power shell or Command Prompt perform following steps (admin privileges):

mkdir layers
cd layers
mkdir python
cd python
pip3 install pycryptodome -t ./

• Now open the python folder in file explorer.

• Zip the python folder along with its child folders.

• Now you are good to go and upload it as layer in AWS.

It will great if you have Linux Machine or Create an EC2 Instance with Ubuntu AMI and Copy the Content to S3, the you can upload it from S3 bucket to AWS lambda layer directly.

Update:

• I have Created Similar Scenario in my environment:

• I installed the Crypto library in my local machine(Ubuntu) as per above mentioned steps.

• Created a Zip.

• Uploaded the ZIP file to create layer and added layer to lambda

• It worked as Charm:

Make Sure to add the layer to lambda My Python version was 3.10 for local and Lambda's python