liboqs-python throws AttributeError: module 'oqs' has no attribute 'get_enabled_kem_mechanisms'

I'm trying to get this Open Quantum Safe example working: https://github.com/open-quantum-safe/liboqs-python/blob/main/examples/kem.py

I'm getting this error:

(myenv) user@mx:~
$ python3 '/home/user/Documents/Dev/quantum_algo_tests/# Key encapsulation Python example.py' 
Enabled KEM mechanisms:
Traceback (most recent call last):
  File "/home/user/Documents/Dev/quantum_algo_tests/# Key encapsulation Python example.py", line 9, in <module>
    kems = oqs.get_enabled_kem_mechanisms()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: module 'oqs' has no attribute 'get_enabled_kem_mechanisms'
(myenv) user@mx:~
$

Running inspect to list functions I get:

ExpressionInput
FunctionNode
OQSInterpreter
oqs_engine

I tried a basic example from following the documentation:

import oqs
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
import os
import base64

# Message to be encrypted
message = "Hello world!"

# Step 1: Key Encapsulation using Kyber
kemalg = "Kyber512"
with oqs.KeyEncapsulation(kemalg) as client:
    # Client generates keypair
    public_key = client.generate_keypair()

    # Server (could be another party) encapsulates secret with client's public key
    with oqs.KeyEncapsulation(kemalg) as server:
        ciphertext, shared_secret_server = server.encap_secret(public_key)
    
    # Client decapsulates to get the same shared secret
    shared_secret_client = client.decap_secret(ciphertext)

# The shared secret is now the same for both client and server and will be used as the encryption key
assert shared_secret_client == shared_secret_server, "Shared secrets do not match!"

# Step 2: Encrypt the message using AES-GCM with the shared secret
iv = os.urandom(12)
cipher = Cipher(algorithms.AES(shared_secret_client), modes.GCM(iv), backend=None)
encryptor = cipher.encryptor()
ciphertext = encryptor.update(message.encode()) + encryptor.finalize()

# The tag ensures the integrity of the message
tag = encryptor.tag

# Combine the IV, ciphertext, and tag into a single encrypted package
encrypted_message = base64.b64encode(iv + ciphertext + tag)

print(f"Encrypted message: {encrypted_message.decode()}")

# Step 3: Decryption process (using the shared secret derived from Kyber)

# Decrypt the message
decryptor = Cipher(algorithms.AES(shared_secret_server), modes.GCM(iv, tag), backend=None).decryptor()
decrypted_message = decryptor.update(ciphertext) + decryptor.finalize()

print(f"Decrypted message: {decrypted_message.decode()}")

I get the same error:

$ python3 /home/user/Documents/Dev/quantum_algo_tests/hello_world_example.py 
Traceback (most recent call last):
  File "/home/user/Documents/Dev/quantum_algo_tests/hello_world_example.py", line 11, in <module>
    with oqs.KeyEncapsulation(kemalg) as client:
         ^^^^^^^^^^^^^^^^^^^^
AttributeError: module 'oqs' has no attribute 'KeyEncapsulation'

Why is such a simple program throwing this error?

Solution

Chances are, liboqs just wasn't installed correctly. The GitHub page gives several installation steps, some of which are contradictory and could break your install. (When I tried following the instructions from top to bottom, I got a version conflict due to incompatible installs of oqs and liboqs-python.)

The safest option is to exclusively follow the "Let liboqs-python install liboqs automatically" section and ignore everything preceding and following it.

Just activate your desired venv, then paste the following lines into your terminal:

git clone --depth=1 https://github.com/open-quantum-safe/liboqs-python
cd liboqs-python
pip install .