From 6f139c910884a94dd755a5d58482cb3652b1480c Mon Sep 17 00:00:00 2001
From: Andrew Kozlik <andrew.kozlik@gmail.com>
Date: Wed, 23 Aug 2023 16:21:29 +0200
Subject: [PATCH] feat(core): Implement AuthenticateDevice message.

---
 core/.changelog.d/3255.added                  |  1 +
 core/src/all_modules.py                       |  2 +
 .../apps/management/authenticate_device.py    | 50 +++++++++++++++++++
 core/src/apps/workflow_handlers.py            |  3 ++
 4 files changed, 56 insertions(+)
 create mode 100644 core/.changelog.d/3255.added
 create mode 100644 core/src/apps/management/authenticate_device.py

diff --git a/core/.changelog.d/3255.added b/core/.changelog.d/3255.added
new file mode 100644
index 0000000000..77f420f8f6
--- /dev/null
+++ b/core/.changelog.d/3255.added
@@ -0,0 +1 @@
+Implement device authentication for Model R.
diff --git a/core/src/all_modules.py b/core/src/all_modules.py
index 60ac66b011..e66de0e36a 100644
--- a/core/src/all_modules.py
+++ b/core/src/all_modules.py
@@ -313,6 +313,8 @@ apps.management.apply_flags
 import apps.management.apply_flags
 apps.management.apply_settings
 import apps.management.apply_settings
+apps.management.authenticate_device
+import apps.management.authenticate_device
 apps.management.backup_device
 import apps.management.backup_device
 apps.management.backup_types
diff --git a/core/src/apps/management/authenticate_device.py b/core/src/apps/management/authenticate_device.py
new file mode 100644
index 0000000000..b98428dfd4
--- /dev/null
+++ b/core/src/apps/management/authenticate_device.py
@@ -0,0 +1,50 @@
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from trezor.messages import AuthenticateDevice, AuthenticityProof
+
+
+async def authenticate_device(msg: AuthenticateDevice) -> AuthenticityProof:
+    from trezor import utils, wire
+    from trezor.crypto import optiga
+    from trezor.crypto.der import read_length
+    from trezor.crypto.hashlib import sha256
+    from trezor.messages import AuthenticityProof
+    from trezor.ui.layouts import confirm_action
+    from trezor.utils import BufferReader
+
+    from apps.common.writers import write_compact_size
+
+    await confirm_action(
+        "authenticate_device",
+        "Authenticate device",
+        description="Do you wish to verify the authenticity of your device?",
+    )
+
+    header = b"AuthenticateDevice:"
+    h = utils.HashWriter(sha256())
+    write_compact_size(h, len(header))
+    h.extend(header)
+    write_compact_size(h, len(msg.challenge))
+    h.extend(msg.challenge)
+
+    try:
+        signature = optiga.sign(optiga.DEVICE_ECC_KEY_INDEX, h.get_digest())
+    except optiga.SigningInaccessible:
+        raise wire.ProcessError("Signing inaccessible.")
+
+    certificates = []
+    r = BufferReader(optiga.get_certificate(optiga.DEVICE_CERT_INDEX))
+    while r.remaining_count() > 0:
+        cert_begin = r.offset
+        if r.get() != 0x30:
+            wire.FirmwareError("Device certificate is corrupted.")
+        n = read_length(r)
+        cert_len = r.offset - cert_begin + n
+        r.seek(cert_begin)
+        certificates.append(r.read_memoryview(cert_len))
+
+    return AuthenticityProof(
+        certificates=certificates,
+        signature=signature,
+    )
diff --git a/core/src/apps/workflow_handlers.py b/core/src/apps/workflow_handlers.py
index a4951409f4..fd184be6e3 100644
--- a/core/src/apps/workflow_handlers.py
+++ b/core/src/apps/workflow_handlers.py
@@ -59,6 +59,9 @@ def _find_message_handler_module(msg_type: int) -> str:
     if utils.USE_SD_CARD and msg_type == MessageType.SdProtect:
         return "apps.management.sd_protect"
 
+    if utils.USE_OPTIGA and msg_type == MessageType.AuthenticateDevice:
+        return "apps.management.authenticate_device"
+
     # bitcoin
     if msg_type == MessageType.AuthorizeCoinJoin:
         return "apps.bitcoin.authorize_coinjoin"