1 files changed, 141 insertions, 0 deletions
diff --git a/fw/hid-dials/tools/presig_gen.py b/fw/hid-dials/tools/presig_gen.py
new file mode 100644
index 0000000..c5dafe7
--- /dev/null
+++ b/fw/hid-dials/tools/presig_gen.py
@@ -0,0 +1,141 @@
+#!/usr/bin/env python3
+
+import os
+import sys
+import textwrap
+import uuid
+import hmac
+import binascii
+import time
+from datetime import datetime
+
+LINKING_KEY_SIZE = 15
+PRESIG_VERSION = '000.001'
+DOMAINS = ['all', 'country', 'region', 'vendor', 'series']
+
+def format_hex(data, indent=4, wrap=True):
+    indent = ' '*indent
+    par = ', '.join(f'0x{b:02x}' for b in data)
+    par = textwrap.fill(par, width=120,
+        initial_indent=indent, subsequent_indent=indent,
+        replace_whitespace=False, drop_whitespace=False)
+    if wrap:
+        return f'{{\n{par}\n}}'
+    return par
+
+def domain_string(domain, value):
+    return f'smart reset domain string v{PRESIG_VERSION}: domain:{domain}={value}'
+
+def keygen_cmd(args):
+    if os.path.exists(args.keyfile) and not args.force:
+        print("Error: keyfile already exists. We won't overwrite it. Instead please remove it manually.",
+                file=sys.stderr)
+        return 1
+
+    root_key = os.urandom(LINKING_KEY_SIZE)
+
+    with open(args.keyfile, 'wb') as f:
+        f.write(binascii.hexlify(root_key))
+        f.write(b'\n')
+    return 0
+
+def gen_at_height(domain, value, height, key):
+    # nanananananana BLOCKCHAIN!
+
+    ds = domain_string(domain, value).encode('utf-8')
+
+    for height in range(height+1):
+        key = hmac.digest(key, ds, 'sha512')[:LINKING_KEY_SIZE]
+
+    return key
+
+def auth_cmd(args):
+    with open(args.keyfile, 'r') as f:
+        root_key = binascii.unhexlify(f.read().strip())
+
+    vals = [ (domain, getattr(args, domain)) for domain in DOMAINS if getattr(args, domain) is not None ]
+    if not vals:
+        vals = [('all', 'all')]
+    for domain, value in vals:
+        auth = gen_at_height(domain, value, args.height, root_key)
+        print(f'{domain}="{value}" @{args.height}: {binascii.hexlify(auth).decode()}')
+
+
+def prekey_cmd(args):
+    with open(args.keyfile, 'r') as f:
+        root_key = binascii.unhexlify(f.read().strip())
+
+    print('#include <stdint.h>')
+    print('#include <assert.h>')
+    print()
+    print('#include "crypto.h"')
+    print()
+
+    bundle_id = uuid.uuid4().bytes
+    print(f'/* bundle id {binascii.hexlify(bundle_id).decode()} */')
+    print(f'uint8_t presig_bundle_id[16] = {format_hex(bundle_id)};')
+    print()
+    print(f'/* generated on {datetime.now()} */')
+    print(f'uint64_t bundle_timestamp = {int(time.time())};')
+    print()
+    print(f'int presig_height = {args.max_height};')
+    print()
+
+    print('const char *presig_domain_strings[_TRIGGER_DOMAIN_COUNT] = {')
+    for domain in DOMAINS:
+        ds = domain_string(domain, getattr(args, domain))
+        assert '"' not in ds
+        print(f'    [TRIGGER_DOMAIN_{domain.upper()}] = "{ds}",')
+    print('};')
+    print()
+
+    print('uint8_t presig_keys[_TRIGGER_DOMAIN_COUNT][PRESIG_MSG_LEN] = {')
+    for domain in DOMAINS:
+        key = gen_at_height(domain, getattr(args, domain), args.max_height, root_key)
+        print(f'    [TRIGGER_DOMAIN_{domain.upper()}] = {{{format_hex(key, indent=0, wrap=False)}}},')
+    print('};')
+
+    print()
+    print('static inline void __hack_asserts_only(void) {')
+    print(f'    static_assert(_TRIGGER_DOMAIN_COUNT == {len(DOMAINS)});')
+    print(f'    static_assert(PRESIG_MSG_LEN == {LINKING_KEY_SIZE});')
+    print('}')
+    print()
+
+
+
+TEST_VENDOR = 'Darthenschmidt Cyberei und Verschleierungstechnik GmbH'
+TEST_SERIES = 'Frobnicator v0.23.7'
+TEST_REGION = 'Neuland'
+TEST_COUNTRY = 'Germany'
+
+if __name__ == '__main__':
+    import argparse
+    parser = argparse.ArgumentParser()
+    parser.add_argument('keyfile', help='Key file to use')
+
+    subparsers = parser.add_subparsers(title='subcommands')
+    keygen_parser = subparsers.add_parser('keygen', help='Generate a new key')
+    keygen_parser.add_argument('-f', '--force', action='store_true', help='Force overwriting existing keyfile')
+    keygen_parser.set_defaults(func=keygen_cmd)
+
+    auth_parser = subparsers.add_parser('auth', help='Generate one-time authentication string')
+    auth_parser.add_argument('height', type=int, help='Authentication string height, counting from 0 (root key)')
+    auth_parser.set_defaults(func=auth_cmd)
+    auth_parser.add_argument('-a', '--all', action='store_const', const='all', help='Vendor name for vendor domain')
+    auth_parser.add_argument('-v', '--vendor', type=str, nargs='?', const=TEST_VENDOR, help='Vendor name for vendor domain')
+    auth_parser.add_argument('-s', '--series', type=str, nargs='?', const=TEST_SERIES, help='Series identifier for series domain')
+    auth_parser.add_argument('-r', '--region', type=str, nargs='?', const=TEST_REGION, help='Region name for region domain')
+    auth_parser.add_argument('-c', '--country', type=str, nargs='?', const=TEST_COUNTRY, help='Country name for country domain')
+
+    prekey_parser = subparsers.add_parser('prekey', help='Generate prekey data .C source code file')
+    prekey_parser.add_argument('-m', '--max-height', type=int, default=8, help='Height of generated prekey')
+    prekey_parser.add_argument('-v', '--vendor', type=str, default=TEST_VENDOR, help='Vendor name for vendor domain')
+    prekey_parser.add_argument('-s', '--series', type=str, default=TEST_SERIES, help='Series identifier for series domain')
+    prekey_parser.add_argument('-r', '--region', type=str, default=TEST_REGION, help='Region name for region domain')
+    prekey_parser.add_argument('-c', '--country', type=str, default=TEST_COUNTRY, help='Country name for country domain')
+    prekey_parser.set_defaults(func=prekey_cmd, all='all')
+
+    args = parser.parse_args()
+    sys.exit(args.func(args))
+