Merge branch '24-generate-certificate-store-base64-string' into 'master'

Generate certificate store base64 string

Closes #24

See merge request internal/development-environment/ts-tvl!19

Author: Adam Vrba

scripts/gen_cert_store.py

@@ -0,0 +1,58 @@
+#!/usr/bin/env python3
+import argparse
+import pathlib
+from cryptography.x509 import load_pem_x509_certificate
+from cryptography.hazmat.primitives.serialization import Encoding
+import base64
+
+def is_file_and_exists(arg) -> pathlib.Path:
+    p = pathlib.Path(arg)
+    if p.is_file() and p.exists():
+        return p
+    raise argparse.ArgumentTypeError(f"Argument is not a valid file: {arg}.")
+
+def load_cert(cert: pathlib.Path) -> bytes:
+    """Load x509 certificate and convert to ASN.1 DER-TLV."""
+    if cert.suffix == ".pem":
+        return load_pem_x509_certificate(cert.read_bytes()).public_bytes(
+            Encoding.DER
+        )
+    if cert.suffix == ".der":
+        return cert.read_bytes()
+    raise argparse.ArgumentTypeError("Certificate not in DER nor PEM format.")
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(
+        prog = "gen_cert_store.py",
+        description = "Creates TROPIC01 Device Certificate Store from input certificates and encodes it as base64."
+    )
+
+    parser.add_argument(
+        "--store-version",
+        help="Certificate store version (from the Certificate Store Header).",
+        type=int,
+        default=1
+    )
+
+    parser.add_argument(
+        "--certs",
+        help="Files with the certificates in PEM or DER format.",
+        type=is_file_and_exists,
+        nargs="+",
+        required=True
+    )
+
+    args = parser.parse_args()
+
+    cert_store_header = args.store_version.to_bytes(1, 'big')
+    cert_store_header += len(args.certs).to_bytes(1, 'big')
+    cert_store_body = b''
+    for c in args.certs:
+        cert_der = load_cert(c)
+        cert_store_header += len(cert_der).to_bytes(2, 'big')
+        cert_store_body += cert_der
+
+    
+    output = base64.b64encode(cert_store_header+cert_store_body)
+    print(f"TROPIC01 Device Certificate Store:\n{output}")