Crypto v2 draft working

3 files changed, 138 insertions, 94 deletions

diff --git a/controller/fw/tools/crypto_test.c b/controller/fw/tools/crypto_test.c
index 8552117..410fac2 100644
--- a/controller/fw/tools/crypto_test.c
+++ b/controller/fw/tools/crypto_test.c
@@ -30,7 +30,7 @@ int main(int argc, char **argv) {
 
     uint8_t auth_key[16];
 
-    for (size_t i=0; argv[1][i+0] != '\0' && argv[1][i+1] != '\0'; i+= 2) {
+    for (size_t i=0; argv[1][i+0] != '\0' && argv[1][i+1] != '\0' && i/2<sizeof(auth_key); i+= 2) {
         char buf[3] = { argv[1][i+0], argv[1][i+1], 0};
         char *endptr;
         auth_key[i/2] = strtoul(buf, &endptr, 16);
diff --git a/controller/fw/tools/crypto_test_runner.py b/controller/fw/tools/crypto_test_runner.py
new file mode 100644
index 0000000..34c8b59
--- /dev/null
+++ b/controller/fw/tools/crypto_test_runner.py
@@ -0,0 +1,46 @@
+#!/usr/bin/env python3
+import subprocess
+from os import path
+import binascii
+import re
+
+import presig_gen
+
+def do_test(domain, value, height, root_key, binary, expect_fail=False):
+    auth = presig_gen.gen_at_height(domain, value, height, root_key)
+    auth = binascii.hexlify(auth).decode()
+
+    output = subprocess.check_output([binary, auth])
+    *lines, rc_line = output.decode().splitlines()
+    rc = int(re.match('^rc=(\d+)$', rc_line).group(1))
+    assert expect_fail == (rc == 0)
+
+def run_tests(root_key, max_height, binary):
+    for domain, value in {
+            'all': 'all',
+            'vendor': presig_gen.TEST_VENDOR,
+            'series': presig_gen.TEST_SERIES,
+            'country': presig_gen.TEST_COUNTRY,
+            'region': presig_gen.TEST_REGION,
+            }.items():
+        for height in range(max_height):
+            do_test(domain, value, height, root_key, binary)
+            do_test(domain, 'fail', height, root_key, binary, expect_fail=True)
+            do_test('fail', 'fail', height, root_key, binary, expect_fail=True)
+            do_test('', '', height, root_key, binary, expect_fail=True)
+        do_test(domain, value, max_height, root_key, binary, expect_fail=True)
+        do_test(domain, value, max_height+1, root_key, binary, expect_fail=True)
+
+if __name__ == '__main__':
+    import argparse
+    parser = argparse.ArgumentParser()
+    parser.add_argument('keyfile', help='Root key file')
+    parser.add_argument('max_height', type=int, default=8, nargs='?', help='Height of generated prekeys')
+    default_binary = path.abspath(path.join(path.dirname(__file__), '../build/tools/crypto_test'))
+    parser.add_argument('binary', default=default_binary, nargs='?', help='crypto_test binary to use')
+    args = parser.parse_args()
+
+    with open(args.keyfile, 'r') as f:
+        root_key = binascii.unhexlify(f.read().strip())
+
+    run_tests(root_key, args.max_height, args.binary)
diff --git a/controller/fw/tools/presig_gen.py b/controller/fw/tools/presig_gen.py
index 2d97391..ff9dffe 100644
--- a/controller/fw/tools/presig_gen.py
+++ b/controller/fw/tools/presig_gen.py
@@ -4,19 +4,14 @@ import os
 import sys
 import textwrap
 import uuid
-import hashlib
+import hmac
 import binascii
-import sqlite3
 import time
+from datetime import datetime
 
-import nacl.signing
-import nacl.encoding
-
-from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
-from cryptography.hazmat.backends import default_backend
-
-
+LINKING_KEY_SIZE = 16
 PRESIG_VERSION = '000.001'
+DOMAINS = ['all', 'country', 'region', 'vendor', 'series']
 
 def format_hex(data, indent=4, wrap=True):
     indent = ' '*indent
@@ -28,48 +23,47 @@ def format_hex(data, indent=4, wrap=True):
         return f'{{\n{par}\n}}'
     return par
 
-def domain_string(domain_name, value, serial):
-    return f'smart reset domain string v{PRESIG_VERSION}: domain:{domain_name}={value}@{serial}'
+def domain_string(domain, value):
+    return f'smart reset domain string v{PRESIG_VERSION}: domain:{domain}={value}'
 
-if __name__ == '__main__':
-    import argparse
-    parser = argparse.ArgumentParser()
-    parser.add_argument('keyfile', help='Key file to use')
-    parser.add_argument('presig_db', nargs='?', help='sqlite3 dbfile for generated presig authorization keys')
-    parser.add_argument('-g', '--generate', action='store_true', help='Generate signing keypair')
-    parser.add_argument('-v', '--vendor', type=str, default='Darthenschmidt Cyberei und Verschleierungstechnik GmbH', help='Vendor name for vendor domain')
-    parser.add_argument('-s', '--series', type=str, default='Frobnicator v0.23.7', help='Series identifier for series domain')
-    parser.add_argument('-r', '--region', type=str, default='Neuland', help='Region name for region domain')
-    parser.add_argument('-c', '--country', type=str, default='Germany', help='Country name for country domain')
-    parser.add_argument('-p', '--start-serial', type=int, default=0, help='First presig serial number to use')
-    parser.add_argument('-n', '--presig-count', type=int, default=3, help='Number of presigs to generate')
-    parser.add_argument('-i', '--iv', type=str, default='safety reset oob presig iv', help='IV for presig generation')
-    args = parser.parse_args()
+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)
 
-    if args.generate:
-        if os.path.exists(args.keyfile):
-            print("Error: keyfile already exists. We won't overwrite it. Instead please remove it manually.",
-                    file=sys.stderr)
-            sys.exit(1)
-        signing_key = nacl.signing.SigningKey.generate()
-        with open(args.keyfile, 'wb') as f:
-            f.write(signing_key.encode(encoder=nacl.encoding.Base64Encoder))
-            f.write(b'\n')
-        sys.exit(0)
+    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:
-        signing_key = nacl.signing.SigningKey(f.read().strip(), encoder=nacl.encoding.Base64Encoder)
-        pubkey_bytes = signing_key.verify_key.encode(encoder=nacl.encoding.RawEncoder)
-        pubkey_hash = hashlib.sha512(pubkey_bytes).digest()[:16]
+        root_key = binascii.unhexlify(f.read().strip())
 
-    if not args.presig_db:
-        print('The presig_db parameter is required.', file=sys.stderr)
-        sys.exit(1)
+    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()}')
 
-    db = sqlite3.connect(args.presig_db)
-    db.execute('CREATE TABLE IF NOT EXISTS presig_authkey (timestamp, pubkey_hash, bundle_id, presig_ver, domain, value, serial, authkey)')
 
-    bundle_id = uuid.uuid4().bytes
+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>')
@@ -77,67 +71,71 @@ if __name__ == '__main__':
     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(f'int presig_first_serial = {args.start_serial};')
     print()
-
-    print(f'uint8_t oob_trigger_pubkey[crypto_sign_PUBLICKEYBYTES] = {format_hex(pubkey_bytes)};')
+    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('uint8_t presig_messages[_TRIGGER_DOMAIN_COUNT][PRESIG_STORE_SIZE][PRESIG_MSG_LEN] = {')
-    device_domains = {
-            'all': 'all',
-            'country': args.country,
-            'region': args.region,
-            'vendor': args.vendor,
-            'series': args.series
-            }
-    presigs = { dom: [] for dom in device_domains }
-    for dom, val in device_domains.items():
-        print('    {')
-        for i in range(args.presig_count):
-            serial = args.start_serial + i
-            ds = domain_string(dom, val, serial)
-            ds_hash = hashlib.sha512(ds.encode()).digest()[:16]
-            presigs[dom].append((ds_hash, val, serial))
-            print(f'        {{ /* "{ds}" */')
-            print(format_hex(ds_hash, indent=8, wrap=False))
-            print(f'        }},')
-        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()
 
-    presig_iv = hashlib.sha512(args.iv.encode()).digest()[:16]
-    print(f'uint8_t oob_presig_iv[16] = {{ /* sha512("{args.iv}")[:16] */')
-    print(format_hex(presig_iv, wrap=False))
-    print(f'}};')
+    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()
 
 
-    print('uint8_t presig_store[_TRIGGER_DOMAIN_COUNT][PRESIG_STORE_SIZE][crypto_sign_BYTES] = {')
-    for dom, hashes in presigs.items():
-        print(f'    {{ /* domain {dom} */')
 
-        for ds_hash, val, serial in hashes:
-            authkey = os.urandom(16)
-            cipher = Cipher(algorithms.AES(authkey), modes.CTR(presig_iv), backend=default_backend())
-            enc = cipher.encryptor()
-            ciphertext = enc.update(ds_hash)
-            assert len(enc.finalize()) == 0
+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')
 
-            with db:
-                db.execute('INSERT INTO presig_authkey VALUES (?, ?, ?, ?, ?, ?, ?, ?)',
-                        (int(time.time()*1000), pubkey_hash, binascii.hexlify(bundle_id).decode(), PRESIG_VERSION, dom,
-            print(format_hex(ciphertext, indent=8, wrap=False))
-            print(f'        }},')
+    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')
 
-        print(f'    }},')
-    print(f'}};')
+    args = parser.parse_args()
+    sys.exit(args.func(args))
 
-    print()
-    print('static inline void __hack_asserts_only(void) {')
-    print(f'    static_assert(_TRIGGER_DOMAIN_COUNT == {len(presigs)});')
-    print(f'    static_assert(PRESIG_STORE_SIZE == {args.presig_count});')
-    print('}')
-    print()