create_keypair.py

import argparse, json, os

from schnorr_lib import n, has_even_y, pubkey_point_gen_from_int, bytes_from_point 


def create_keypair(n_keys: int):
    # Create json
    users = {
        "$schema": "./users_schema.json",
        "users": []
    }

    # Generate n keys
    for i in range(0, n_keys):
        privkey = os.urandom(32)
        privkey_int = int(privkey.hex(), 16) % n

        publickey = pubkey_point_gen_from_int(privkey_int)

        # Check if the point P has the y-coordinate even; negate the private key otherwise
        privkey_even = privkey_int if has_even_y(publickey) else n - privkey_int

        hex_privkey = hex(privkey_even).replace('0x', '').rjust(64, '0')
        users["users"].append({
            "privateKey": hex_privkey,
            "publicKey": bytes_from_point(publickey).hex()
        })
    return users


def main():
    parser = argparse.ArgumentParser(description='Creates one or more key pairs which are stored in a JSON file and can be used to sign and verify a message')
    parser.add_argument('-n', '--nkeys', type=int, required=False, help='Number of pairs of keys to generate, if not specified a single keypair will be generated')
    n_keys = parser.parse_args().nkeys

    if not n_keys: 
        n_keys = 1

    users = create_keypair(n_keys)

    json_object = json.dumps(users, indent=4)
    with open("users.json", "w") as f:
        f.write(json_object)

    print("[i] Keypair(s) generated:", n_keys)


if __name__ == "__main__":
    main()