From 6c124515b502b0956c0225fb6c7a1ab48d49111a Mon Sep 17 00:00:00 2001
From: Andrzej Kaczmarek <andrzej.kaczmarek@codecoup.pl>
Date: Thu, 26 Jan 2023 23:42:33 +0100
Subject: [PATCH] nimble/ll: Add some crypto functions

This adds h6, h7 and h8 crypto functions that are used to derive GSK
from broadcast code. For now we use TinyCrypt, later we may use hw
accelerators as an option.
---
 .../include/controller/ble_ll_crypto.h        | 50 +++++++++++++++
 nimble/controller/pkg.yml                     |  1 +
 nimble/controller/src/ble_ll_crypto.c         | 62 +++++++++++++++++++
 3 files changed, 113 insertions(+)
 create mode 100644 nimble/controller/include/controller/ble_ll_crypto.h
 create mode 100644 nimble/controller/src/ble_ll_crypto.c

diff --git a/nimble/controller/include/controller/ble_ll_crypto.h b/nimble/controller/include/controller/ble_ll_crypto.h
new file mode 100644
index 000000000..4514b0b10
--- /dev/null
+++ b/nimble/controller/include/controller/ble_ll_crypto.h
@@ -0,0 +1,50 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef H_BLE_LL_CRYPTO_
+#define H_BLE_LL_CRYPTO_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int
+ble_ll_crypto_cmac(const uint8_t *key, const uint8_t *in, int len,
+                   uint8_t *out);
+
+static inline int
+ble_ll_crypto_h6(const uint8_t *w, const uint8_t *key_id, uint8_t *out)
+{
+    return ble_ll_crypto_cmac(w, key_id, 4, out);
+}
+
+static inline int
+ble_ll_crypto_h7(const uint8_t *salt, const uint8_t *w, uint8_t *out)
+{
+    return ble_ll_crypto_cmac(salt, w, 16, out);
+}
+
+int ble_ll_crypto_h8(const uint8_t *k, const uint8_t *s, const uint8_t *key_id,
+                     uint8_t *out);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* H_BLE_LL_CRYPTO_ */
diff --git a/nimble/controller/pkg.yml b/nimble/controller/pkg.yml
index 678fea17b..5e43ba39d 100644
--- a/nimble/controller/pkg.yml
+++ b/nimble/controller/pkg.yml
@@ -38,5 +38,6 @@ pkg.req_apis.BLE_FEM_ANTENNA:
 
 pkg.deps:
     - "@apache-mynewt-core/kernel/os"
+    - "@apache-mynewt-core/crypto/tinycrypt"
     - nimble
     - nimble/transport
diff --git a/nimble/controller/src/ble_ll_crypto.c b/nimble/controller/src/ble_ll_crypto.c
new file mode 100644
index 000000000..be3e1be3b
--- /dev/null
+++ b/nimble/controller/src/ble_ll_crypto.c
@@ -0,0 +1,62 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include <stdint.h>
+#include <nimble/ble.h>
+#include <controller/ble_ll_crypto.h>
+#include <controller/ble_hw.h>
+#include <tinycrypt/constants.h>
+#include <tinycrypt/cmac_mode.h>
+
+int
+ble_ll_crypto_cmac(const uint8_t *key, const uint8_t *in, int len,
+                   uint8_t *out)
+{
+    struct tc_aes_key_sched_struct sched;
+    struct tc_cmac_struct state;
+
+    if (tc_cmac_setup(&state, key, &sched) == TC_CRYPTO_FAIL) {
+        return -1;
+    }
+
+    if (tc_cmac_update(&state, in, len) == TC_CRYPTO_FAIL) {
+        return -1;
+    }
+
+    if (tc_cmac_final(out, &state) == TC_CRYPTO_FAIL) {
+        return -1;
+    }
+
+    return 0;
+}
+
+int
+ble_ll_crypto_h8(const uint8_t *k, const uint8_t *s, const uint8_t *key_id,
+                 uint8_t *out)
+{
+    uint8_t ik[16];
+    int rc;
+
+    rc = ble_ll_crypto_cmac(s, k, 16, ik);
+    if (rc) {
+        return rc;
+    }
+
+    return ble_ll_crypto_cmac(ik, key_id, 4, out);
+}