From 0cd07d397fb5a5e7710af66cb1e9e0b61705c94a Mon Sep 17 00:00:00 2001
From: jaseg <git-bigdata-wsl-arch@jaseg.de>
Date: Tue, 10 Mar 2020 12:20:55 +0100
Subject: Crypto v2 draft working

---
 controller/fw/Makefile                    |   6 +-
 controller/fw/crypto-algorithms           |   1 +
 controller/fw/src/crypto.c                |  80 +++++++++----
 controller/fw/src/crypto.h                |  20 ++--
 controller/fw/tools/crypto_test.c         |   2 +-
 controller/fw/tools/crypto_test_runner.py |  46 ++++++++
 controller/fw/tools/presig_gen.py         | 184 +++++++++++++++---------------
 7 files changed, 206 insertions(+), 133 deletions(-)
 create mode 160000 controller/fw/crypto-algorithms
 create mode 100644 controller/fw/tools/crypto_test_runner.py

(limited to 'controller/fw')

diff --git a/controller/fw/Makefile b/controller/fw/Makefile
index c678963..85ab02f 100644
--- a/controller/fw/Makefile
+++ b/controller/fw/Makefile
@@ -62,7 +62,7 @@ PAYLOAD_DATA_BIT		?= 64
 TRANSMISSION_SYMBOLS	?= 32
 PRESIG_STORE_SIZE		?= 3
 
-PRESIG_KEYFILE			?= presig_test_key.private
+PRESIG_KEYFILE			?= presig_test_key.secret
 PRESIG_DBFILE			?= presig_test_db.sqlite3
 
 CC			:= $(PREFIX)gcc
@@ -161,11 +161,11 @@ $(BUILDDIR)/generated/dsss_butter_filter.h: | $(BUILDDIR)/generated
 
 .PRECIOUS: $(BUILDDIR)/generated/crypto_presig_data.c
 $(BUILDDIR)/generated/crypto_presig_data.c: $(PRESIG_KEYFILE) tools/presig_gen.py | $(BUILDDIR)/generated
-	$(PYTHON3) tools/presig_gen.py $(PRESIG_KEYFILE) $(PRESIG_DBFILE) > $@
+	$(PYTHON3) tools/presig_gen.py $(PRESIG_KEYFILE) prekey > $@
 
 .PRECIOUS: $(PRESIG_KEYFILE)
 $(PRESIG_KEYFILE):
-	$(PYTHON3) tools/presig_gen.py -g $@
+	$(PYTHON3) tools/presig_gen.py $@ keygen
 
 $(BUILDDIR)/generated: ; mkdir -p $@
 
diff --git a/controller/fw/crypto-algorithms b/controller/fw/crypto-algorithms
new file mode 160000
index 0000000..cfbde48
--- /dev/null
+++ b/controller/fw/crypto-algorithms
@@ -0,0 +1 @@
+Subproject commit cfbde48414baacf51fc7c74f275190881f037d32
diff --git a/controller/fw/src/crypto.c b/controller/fw/src/crypto.c
index 73ad783..db35745 100644
--- a/controller/fw/src/crypto.c
+++ b/controller/fw/src/crypto.c
@@ -1,16 +1,22 @@
 
+#include <assert.h>
 #include <unistd.h>
 #include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 
-#include <aes.h>
+#include <sodium.h>
 
 #include "crypto.h"
 #include "simulation.h"
 
-void debug_hexdump(const char *name, uint8_t *buf, size_t len);
-void debug_hexdump(const char *name, uint8_t *buf, size_t len) {
+
+void debug_hexdump(const char *name, const uint8_t *buf, size_t len);
+int verify_trigger_dom(const uint8_t inkey[PRESIG_MSG_LEN],
+        const char *domain_string, const uint8_t refkey[PRESIG_MSG_LEN]);
+
+
+void debug_hexdump(const char *name, const uint8_t *buf, size_t len) {
     DEBUG_PRINTN("%20s: ", name);
     for (size_t i=0; i<len;) {
         for (size_t j=0; j<8 && i<len; i++, j++)
@@ -20,29 +26,55 @@ void debug_hexdump(const char *name, uint8_t *buf, size_t len) {
     DEBUG_PRINTN("\n");
 }
 
-int oob_message_received(uint8_t msg[static OOB_TRIGGER_LEN]) {
-    struct AES_ctx ctx;
-    uint8_t buf[crypto_sign_BYTES];
-
-    for (size_t serial=0; serial<PRESIG_STORE_SIZE; serial++) {
-        for (size_t dom=0; dom<_TRIGGER_DOMAIN_COUNT; dom++) {
-
-            DEBUG_PRINT("Trying domain %zd serial %zd", dom, serial);
-            debug_hexdump("oob_presig_iv", oob_presig_iv, sizeof(oob_presig_iv));
-
-            memcpy(buf, presig_store[dom][serial], crypto_sign_BYTES);
-            debug_hexdump("presig", buf, sizeof(buf));
-            AES_init_ctx_iv(&ctx, msg, oob_presig_iv);
-            AES_CBC_decrypt_buffer(&ctx, buf, crypto_sign_BYTES);
-            debug_hexdump("decrypted", buf, sizeof(buf));
-
-            if (!crypto_sign_verify_detached(buf, presig_messages[dom][serial], PRESIG_MSG_LEN, oob_trigger_pubkey)) {
-                oob_trigger_activated(dom, presig_first_serial + serial);
-                return 1;
-            }
-            DEBUG_PRINTN("\n");
+/* Returns 1 for correct trigger */
+int verify_trigger_dom(const uint8_t inkey[PRESIG_MSG_LEN],
+        const char *domain_string, const uint8_t refkey[PRESIG_MSG_LEN]) {
+    uint8_t key[crypto_auth_hmacsha512_KEYBYTES];
+    uint8_t key_out[crypto_auth_hmacsha512_BYTES];
+
+    static_assert(PRESIG_MSG_LEN <= crypto_auth_hmacsha512_KEYBYTES);
+    memcpy(key, inkey, PRESIG_MSG_LEN);
+    memset(key + PRESIG_MSG_LEN, 0, sizeof(key) - PRESIG_MSG_LEN);
+    DEBUG_PRINT("ds \"%s\"", domain_string);
+    debug_hexdump("ref", refkey, PRESIG_MSG_LEN);
+
+    for (int i=0; i<presig_height; i++) {
+        DEBUG_PRINT("Verifying height rel %d abs %d", i, presig_height-i);
+        debug_hexdump("key", key, sizeof(key));
+        (void)crypto_auth_hmacsha512(key_out, (uint8_t *)domain_string, strlen(domain_string), key);
+        debug_hexdump("out", key_out, sizeof(key_out));
+        memcpy(key, key_out, PRESIG_MSG_LEN);
+        memset(key + PRESIG_MSG_LEN, 0, sizeof(key) - PRESIG_MSG_LEN);
+        
+        if (!memcmp(key, refkey, PRESIG_MSG_LEN))
+            return presig_height-i;
+    }
+
+    return 0;
+}
+
+int verify_trigger(const uint8_t inkey[PRESIG_MSG_LEN], int *height_out, int *domain_out) {
+    int res;
+    for (int i=0; i<_TRIGGER_DOMAIN_COUNT; i++) {
+        DEBUG_PRINT("Verifying domain %d", i);
+        if ((res = verify_trigger_dom(inkey, presig_domain_strings[i], presig_keys[i]))) {
+            DEBUG_PRINT("Match!");
+            if (height_out)
+                *height_out = res - 1;
+            if (domain_out)
+                *domain_out = i;
+            return 1;
         }
     }
+    return 0;
+}
+
+int oob_message_received(uint8_t msg[static OOB_TRIGGER_LEN]) {
+    int height, domain;
+    if (verify_trigger(msg, &height, &domain)) {
+        oob_trigger_activated(domain, height);
+        return 1;
+    }
 
     return 0;
 }
diff --git a/controller/fw/src/crypto.h b/controller/fw/src/crypto.h
index 61a0da8..05a3c0d 100644
--- a/controller/fw/src/crypto.h
+++ b/controller/fw/src/crypto.h
@@ -3,12 +3,8 @@
 
 #include <stdint.h>
 
-#include <sodium.h>
-
-
-#define OOB_TRIGGER_LEN 16
 #define PRESIG_MSG_LEN 16
-
+#define OOB_TRIGGER_LEN PRESIG_MSG_LEN
 
 enum trigger_domain {
     TRIGGER_DOMAIN_ALL,
@@ -19,15 +15,15 @@ enum trigger_domain {
     _TRIGGER_DOMAIN_COUNT
 };
 
-extern uint8_t presig_store[_TRIGGER_DOMAIN_COUNT][PRESIG_STORE_SIZE][crypto_sign_BYTES];
-extern uint8_t oob_trigger_pubkey[crypto_sign_PUBLICKEYBYTES];
-extern uint8_t presig_messages[_TRIGGER_DOMAIN_COUNT][PRESIG_STORE_SIZE][PRESIG_MSG_LEN];
-extern uint8_t oob_presig_iv[16];
-extern int presig_first_serial;
-
+extern const char *presig_domain_strings[_TRIGGER_DOMAIN_COUNT];
+extern uint8_t presig_keys[_TRIGGER_DOMAIN_COUNT][PRESIG_MSG_LEN];
+extern int presig_height;
+extern uint8_t presig_bundle_id[16];
+extern uint64_t bundle_timestamp;
 
-extern void oob_trigger_activated(enum trigger_domain domain, int serial);
+extern void oob_trigger_activated(enum trigger_domain domain, int height);
 
 int oob_message_received(uint8_t msg[static OOB_TRIGGER_LEN]);
+int verify_trigger(const uint8_t inkey[PRESIG_MSG_LEN], int *height_out, int *domain_out);
 
 #endif /* __CRYPTO_H__ */
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()
-- 
cgit