I face one error when i was doing data_exchange. I used facebook’s example of data_exchange.

I am getting this error

We failed to decrypt your payload. Please check your encryption/decryption logic.

Here it is my decryption code and it is working fine
`

def decrypt_request(self,encrypted_flow_data_b64, encrypted_aes_key_b64, initial_vector_b64):
flow_data = b64decode(encrypted_flow_data_b64)
iv = b64decode(initial_vector_b64)

    # Decrypt the AES encryption key
    encrypted_aes_key = b64decode(encrypted_aes_key_b64)
    
    PRIVATE_KEY = request.env['res.company'].search([],limit=1)
    encoded_data = b64decode(PRIVATE_KEY.private_key_attachment).decode('utf-8').encode('utf-8')
    private_key = load_pem_private_key(
        encoded_data, password=None)
    aes_key = private_key.decrypt(encrypted_aes_key, OAEP(
        mgf=MGF1(algorithm=hashes.SHA256()), algorithm=hashes.SHA256(), label=None))

    # Decrypt the Flow data
    encrypted_flow_data_body = flow_data[:-16]
    encrypted_flow_data_tag = flow_data[-16:]
    decryptor = Cipher(algorithms.AES(aes_key),
                       modes.GCM(iv, encrypted_flow_data_tag)).decryptor()
    decrypted_data_bytes = decryptor.update(
        encrypted_flow_data_body) + decryptor.finalize()
    decrypted_data = json.loads(decrypted_data_bytes.decode("utf-8"))
    return decrypted_data, aes_key, iv`

Here it is my encryption code
`

def encrypt_response(self,response, aes_key, iv):
# Flip the initialization vector
flipped_iv = bytearray(b ^ 0xFF for b in iv)

    # Encrypt the response data
    encryptor = Cipher(
        algorithms.AES(aes_key),
        modes.GCM(flipped_iv[:12]),
        backend=default_backend()
    ).encryptor()
    
    # Encrypt and finalize
    response_bytes = json.dumps(response).encode("utf-8")
    ciphertext = encryptor.update(response_bytes) + encryptor.finalize()
    
    # Combine ciphertext and tag
    encrypted_payload = ciphertext + encryptor.tag
    
    # Encode as base64
    encoded_payload = b64encode(encrypted_payload).decode("utf-8")
    
    return encoded_payload

`

and this is main method
`

def whatsapp_data_exchange_flow(self,**kw):
data = json.loads(request.httprequest.data)

    # Read the request fields
    encrypted_flow_data_b64 = data['encrypted_flow_data']
    encrypted_aes_key_b64 = data['encrypted_aes_key']
    initial_vector_b64 = data['initial_vector']

    decrypted_data, aes_key, iv = self.decrypt_request(
        encrypted_flow_data_b64, encrypted_aes_key_b64, initial_vector_b64)
    print(decrypted_data)

    # Return the next screen & data to the client
    response = {
        "version": "3.0",
        "screen": "BOOKING_INFO"
    }
    encrpted_response = self.encrypt_response(response, aes_key, iv)

    headers = werkzeug.datastructures.Headers(None)
    headers['Content-Type'] = 'text/plain'
    response = request.make_response(final_response,headers=headers.to_wsgi_list(),status=200)
    return response`