From dad7d904818ddefee302efafd87df94e43d627a8 Mon Sep 17 00:00:00 2001
From: Conor Patrick <conorpp@vt.edu>
Date: Sun, 15 Jul 2018 01:23:38 -0400
Subject: [PATCH] bootloader verifies signature

---
 .gitignore             |  1 +
 efm32boot/.cproject    |  2 +-
 efm32boot/inc/app.h    |  2 ++
 efm32boot/src/boot.c   |  4 ++--
 efm32boot/src/main.c   |  8 ++++++--
 tools/gen_keys.py      | 20 ++++++++++++++++++++
 tools/http2udb.py      | 32 +++++++++++++++++++++++++++++---
 tools/requirements.txt |  2 ++
 web/js/wallet.js       | 14 ++++++++++----
 9 files changed, 73 insertions(+), 12 deletions(-)
 create mode 100644 tools/gen_keys.py
 create mode 100644 tools/requirements.txt

diff --git a/.gitignore b/.gitignore
index 5578a4c..14d4f3d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -70,3 +70,4 @@ efm32/hw
 mbedtls/
 sl_crypto/
 tools/python-fido2/*
+*.pem
diff --git a/efm32boot/.cproject b/efm32boot/.cproject
index a6eb75c..f54cab7 100644
--- a/efm32boot/.cproject
+++ b/efm32boot/.cproject
@@ -37,7 +37,7 @@
 							<targetPlatform binaryParser="org.eclipse.cdt.core.ELF;org.eclipse.cdt.core.GNU_ELF;com.silabs.ss.framework.debugger.core.BIN;com.silabs.ss.framework.debugger.core.HEX;com.silabs.ss.framework.debugger.core.S37;com.silabs.ss.framework.debugger.core.EBL;com.silabs.ss.framework.debugger.core.GBL" id="com.silabs.ide.si32.gcc.cdt.managedbuild.target.gnu.platform.base.613101530" isAbstract="false" name="Debug Platform" osList="win32,linux,macosx" superClass="com.silabs.ide.si32.gcc.cdt.managedbuild.target.gnu.platform.base"/>
 							<builder buildPath="${workspace_loc:/efm32boot}/GNU ARM v7.2.1 - Debug" id="com.silabs.ide.si32.gcc.cdt.managedbuild.target.gnu.builder.base.2113865201" keepEnvironmentInBuildfile="false" managedBuildOn="true" name="Si32 GNU ARM Builder" parallelBuildOn="true" parallelizationNumber="optimal" superClass="com.silabs.ide.si32.gcc.cdt.managedbuild.target.gnu.builder.base"/>
 							<tool id="com.silabs.ide.si32.gcc.cdt.managedbuild.tool.gnu.c.compiler.base.981192541" name="GNU ARM C Compiler" superClass="com.silabs.ide.si32.gcc.cdt.managedbuild.tool.gnu.c.compiler.base">
-								<option id="gnu.c.compiler.option.optimization.level.1400029735" name="Optimization Level" superClass="gnu.c.compiler.option.optimization.level" value="gnu.c.optimization.level.none" valueType="enumerated"/>
+								<option id="gnu.c.compiler.option.optimization.level.1400029735" name="Optimization Level" superClass="gnu.c.compiler.option.optimization.level" value="gnu.c.optimization.level.size" valueType="enumerated"/>
 								<option id="com.silabs.ide.si32.gcc.cdt.managedbuild.tool.gnu.c.compiler.def.symbols.115820704" name="Defined symbols (-D)" superClass="com.silabs.ide.si32.gcc.cdt.managedbuild.tool.gnu.c.compiler.def.symbols" valueType="definedSymbols">
 									<listOptionValue builtIn="false" value="DEBUG=1"/>
 									<listOptionValue builtIn="false" value="EFM32PG1B200F256GM48=1"/>
diff --git a/efm32boot/inc/app.h b/efm32boot/inc/app.h
index 8fe4a8b..2fcbcaf 100644
--- a/efm32boot/inc/app.h
+++ b/efm32boot/inc/app.h
@@ -30,4 +30,6 @@ int bootloader_bridge(uint8_t klen, uint8_t * keyh);
 
 int is_authorized_to_boot();
 
+extern uint8_t REBOOT_FLAG;
+
 #endif /* SRC_APP_H_ */
diff --git a/efm32boot/src/boot.c b/efm32boot/src/boot.c
index 605d1d0..79aab6e 100644
--- a/efm32boot/src/boot.c
+++ b/efm32boot/src/boot.c
@@ -51,7 +51,7 @@ __asm void BOOT_jump(uint32_t sp, uint32_t pc)
   bx r1
 }
 #else
-void BOOT_jump(uint32_t sp, uint32_t pc)
+void __attribute__((optimize("O0"))) BOOT_jump(uint32_t sp, uint32_t pc)
 {
   (void) sp;
   (void) pc;
@@ -78,7 +78,7 @@ static void resetPeripherals(void)
  * Boots the firmware. This function will activate the vector table
  * of the firmware application and set the PC and SP from this table.
  *****************************************************************************/
-void BOOT_boot(void)
+void __attribute__((optimize("O0"))) BOOT_boot(void)
 {
   uint32_t pc, sp;
 
diff --git a/efm32boot/src/main.c b/efm32boot/src/main.c
index 4238eb4..30cd67b 100644
--- a/efm32boot/src/main.c
+++ b/efm32boot/src/main.c
@@ -8,7 +8,7 @@
 #include "InitDevice.h"
 
 void bootloader_init(void);
-
+uint8_t REBOOT_FLAG;
 
 int main(void)
 {
@@ -81,7 +81,7 @@ bootmode:
                     //		            printf("accum: %d\n", (uint32_t)accum);
                     //		            printf("dt: %d\n", t2 - dt);
                     //		            dt = t2;
-                    memset(hidmsg, 0, sizeof(hidmsg));
+//                    memset(hidmsg, 0, sizeof(hidmsg));
                 }
                 else
                 {
@@ -89,7 +89,11 @@ bootmode:
                 }
                 ctaphid_check_timeouts();
 
+                if (REBOOT_FLAG) break;
             }
+
+//            delay(100);
+
         }
     }
 
diff --git a/tools/gen_keys.py b/tools/gen_keys.py
new file mode 100644
index 0000000..197ef72
--- /dev/null
+++ b/tools/gen_keys.py
@@ -0,0 +1,20 @@
+from ecdsa import SigningKey, NIST256p
+
+sk = SigningKey.generate(curve = NIST256p)
+
+sk_name = 'signing_key.pem'
+print('Signing key for signing device firmware: '+sk_name)
+open(sk_name,'wb+').write(sk.to_pem())
+
+vk = sk.get_verifying_key()
+
+print('Public key in various formats:')
+print()
+print([c for c in vk.to_string()])
+print()
+print(''.join(['%02x'%c for c in vk.to_string()]))
+print()
+print('"\\x' + '\\x'.join(['%02x'%c for c in vk.to_string()]) + '"')
+print()
+
+
diff --git a/tools/http2udb.py b/tools/http2udb.py
index d4c3514..036e1f4 100644
--- a/tools/http2udb.py
+++ b/tools/http2udb.py
@@ -8,9 +8,13 @@ from fido2.ctap import CtapError
 from fido2.ctap1 import CTAP1
 from fido2.ctap2 import *
 from fido2.cose import *
-from fido2.utils import Timeout
+from fido2.utils import Timeout, sha256
 
-import socket,json,base64,ssl
+from intelhex import IntelHex
+
+from ecdsa import SigningKey, NIST256p
+
+import socket,json,base64,ssl,array,binascii
 
 httpport = 8080
 udpport = 8111
@@ -111,10 +115,32 @@ class UDPBridge(BaseHTTPRequestHandler):
         self.send_response(200)
         self.send_header('Content-type','text/json')
 
+        sk = SigningKey.from_pem(open("signing_key.pem").read())
         h = open(HEX_FILE,'r').read()
         h = base64.b64encode(h.encode())
         h = to_websafe(h.decode())
-        sig = [1,2,3,4]
+
+        START = 0x8000
+        END = 2048 * 125 - 4
+
+        ih = IntelHex(HEX_FILE)
+        segs = ih.segments()
+        arr = ih.tobinarray(start = START, size = END-START)
+
+        im_size = END-START
+
+        print('im_size: ', im_size)
+        print('firmware_size: ', len(arr))
+
+        sig = sha256((arr).tobytes())
+        print('hash', binascii.hexlify(sig))
+        sig = sk.sign_digest(sig)
+
+        print('sig', binascii.hexlify(sig))
+
+        sig = base64.b64encode(sig)
+        sig = to_websafe(sig.decode())
+
         #msg = {'data': read()}
         msg = {'firmware': h, 'signature':sig}
 
diff --git a/tools/requirements.txt b/tools/requirements.txt
new file mode 100644
index 0000000..ae093c8
--- /dev/null
+++ b/tools/requirements.txt
@@ -0,0 +1,2 @@
+ecdsa
+intelhex
diff --git a/web/js/wallet.js b/web/js/wallet.js
index e041d27..73510fa 100644
--- a/web/js/wallet.js
+++ b/web/js/wallet.js
@@ -881,9 +881,9 @@ var is_bootloader_ = function(func){
     });
 };
 
-var bootloader_finish_ = function(func){
+var bootloader_finish_ = function(sig,func){
 
-    var req = formatBootRequest(CMD.boot_done);
+    var req = formatBootRequest(CMD.boot_done, 0x8000, sig);
 
     send_msg(req, function(resp){
         if (func)func(resp);
@@ -1338,6 +1338,9 @@ async function run_tests() {
 
 
         p = await get_firmware_http();
+        var sig = websafe2array(p.signature);
+        var badsig = websafe2array(p.signature);
+        badsig[40] = badsig[40] ^ 1;
 
         var blocks = MemoryMap.fromHex(p.firmware);
         var addresses = blocks.keys();
@@ -1358,8 +1361,11 @@ async function run_tests() {
             addr = addresses.next();
         }
 
-        p = await dev.bootloader_finish();
-        console.log(p);
+        p = await dev.bootloader_finish(badsig);
+        TEST(p.status == 'CTAP2_ERR_OPERATION_DENIED', 'Device rejected new image with bad signature');
+
+        p = await dev.bootloader_finish(sig);
+        TEST(p.status == 'CTAP1_SUCCESS', 'Device booted new image with correct signature');
 
     }