commit 45bf8e247f48d87831c723ab49f724417fcc0137
Author: John Smith <me@helldev.net>
Date:   Tue Jan 10 22:18:45 2023 +0100

    Add signer code

diff --git a/signer.py b/signer.py
new file mode 100644
index 0000000..115a5db
--- /dev/null
+++ b/signer.py
@@ -0,0 +1,56 @@
+# coding: utf
+
+from Crypto.Hash import SHA256
+from Crypto.PublicKey import RSA
+from Crypto.Signature import PKCS1_v1_5
+
+import pyqrcode
+import qrcode
+
+import base64
+import json
+
+PRIVATE_KEY_FILE = "domain.key"
+
+BOX_SIZE = 5
+BORDER = 2
+
+
+def sign(message, private_key_str):
+    priv_key = RSA.importKey(private_key_str)
+    h = SHA256.new(message.encode("utf-8"))
+    signature = PKCS1_v1_5.new(priv_key).sign(h)
+    result = base64.b64encode(signature).decode()
+    return result
+
+
+def create_qr(orderId, skuList, output_filename):
+    """
+    Create a QR code for an order and write it as a PNG.
+    Params:
+        * orderId - order identifier.
+        * skuList - list of SKUs of the order.
+        * output_filename: the name of the output file.
+    """
+    with open(PRIVATE_KEY_FILE, "r") as file:
+        key = file.read()
+
+
+    # dump to str to avoid ordering issues when verifying signature
+    order = json.dumps({"i": orderId, "sk": skuList})
+    signed_order = sign(order, key)
+    data = {"o": order, "s": signed_order}
+
+    data_str = json.dumps(data)
+
+    #data_str_compressed = zlib.compress(data_str)
+
+    qr = qrcode.QRCode(version=1, error_correction=qrcode.constants.ERROR_CORRECT_L, box_size=BOX_SIZE, border=BORDER)
+    qr.add_data(data_str)
+    qr.make(fit=True)
+
+    img = qr.make_image(fill_color="black", back_color="white")
+    img.save(output_filename)
+
+
+create_qr("1234-5678", ["001", "002", "003", "004", "005", "006", "007", "008", "009"], "output.png")