[ICD] Add Check-In payload generation

src/crypto/CHIPCryptoPAL.h

@@ -93,6 +93,8 @@ constexpr size_t kAES_CCM128_Block_Length = kAES_CCM128_Key_Length;
 constexpr size_t kAES_CCM128_Nonce_Length = 13;
 constexpr size_t kAES_CCM128_Tag_Length   = 16;
 
+constexpr size_t CHIP_CRYPTO_AEAD_NONCE_LENGTH_BYTES = kAES_CCM128_Nonce_Length;
+
 /* These sizes are hardcoded here to remove header dependency on underlying crypto library
  * in a public interface file. The validity of these sizes is verified by static_assert in
  * the implementation files.

src/protocols/secure_channel/BUILD.gn

@@ -29,6 +29,8 @@ static_library("secure_channel") {
     "CASEServer.h",
     "CASESession.cpp",
     "CASESession.h",
+    "CheckinMessage.cpp",
+    "CheckinMessage.h",
     "DefaultSessionResumptionStorage.cpp",
     "DefaultSessionResumptionStorage.h",
     "PASESession.cpp",
@@ -50,6 +52,7 @@ static_library("secure_channel") {
 
   public_deps = [
     ":type_definitions",
+    "${chip_root}/src/crypto",
     "${chip_root}/src/lib/core",
     "${chip_root}/src/lib/support",
     "${chip_root}/src/messaging",

src/protocols/secure_channel/CheckinMessage.cpp

@@ -0,0 +1,102 @@
+/*
+ *    Copyright (c) 2020 Project CHIP Authors
+ *    All rights reserved.
+ *
+ *    Licensed 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.
+ */
+
+/**
+ *    @file
+ *      This file implements the Matter Checkin protocol.
+ */
+
+#include "CheckinMessage.h"
+#include <lib/core/CHIPCore.h>
+
+#include <lib/core/CHIPEncoding.h>
+#include <protocols/secure_channel/Constants.h>
+
+namespace chip {
+namespace Protocols {
+namespace SecureChannel {
+
+CHIP_ERROR CheckinMessage::GenerateCheckinMessagePayload(Crypto::Aes128KeyHandle & key, CounterType counter,
+                                                         const ByteSpan & appData, MutableByteSpan & output)
+{
+    VerifyOrReturnError(appData.size() <= sMaxAppDataSize, CHIP_ERROR_INVALID_ARGUMENT);
+    VerifyOrReturnError(output.size() >= (appData.size() + sMinPayloadSize), CHIP_ERROR_INVALID_ARGUMENT);
+
+    CHIP_ERROR err            = CHIP_NO_ERROR;
+    uint8_t * appDataStartPtr = output.data() + CHIP_CRYPTO_AEAD_NONCE_LENGTH_BYTES;
+    Encoding::LittleEndian::Put32(appDataStartPtr, counter);
+
+    chip::Crypto::HMAC_sha shaHandler;
+    uint8_t nonceWorkBuffer[CHIP_CRYPTO_HASH_LEN_BYTES] = { 0 };
+
+    ReturnErrorOnFailure(shaHandler.HMAC_SHA256(key.As<Aes128KeyByteArray>(), sizeof(Aes128KeyByteArray), appDataStartPtr,
+                                                sizeof(CounterType), nonceWorkBuffer, CHIP_CRYPTO_HASH_LEN_BYTES));
+
+    static_assert(sizeof(nonceWorkBuffer) >= CHIP_CRYPTO_AEAD_NONCE_LENGTH_BYTES, "We're reading off the end of our buffer.");
+    memcpy(output.data(), nonceWorkBuffer, CHIP_CRYPTO_AEAD_NONCE_LENGTH_BYTES);
+
+    // In place encryption to save some RAM
+    memcpy(appDataStartPtr + sizeof(CounterType), appData.data(), appData.size());
+
+    uint8_t * micPtr = appDataStartPtr + sizeof(CounterType) + appData.size();
+    ReturnErrorOnFailure(Crypto::AES_CCM_encrypt(appDataStartPtr, sizeof(CounterType) + appData.size(), nullptr, 0, key,
+                                                 output.data(), CHIP_CRYPTO_AEAD_NONCE_LENGTH_BYTES, appDataStartPtr, micPtr,
+                                                 CHIP_CRYPTO_AEAD_MIC_LENGTH_BYTES));
+
+    output.reduce_size(appData.size() + sMinPayloadSize);
+
+    return err;
+}
+
+CHIP_ERROR CheckinMessage::ParseCheckinMessagePayload(Crypto::Aes128KeyHandle & key, ByteSpan & payload, CounterType & counter,
+                                                      MutableByteSpan & appData)
+{
+    VerifyOrReturnError(payload.size() >= sMinPayloadSize, CHIP_ERROR_INVALID_ARGUMENT);
+    VerifyOrReturnError(payload.size() <= (sMinPayloadSize + sMaxAppDataSize), CHIP_ERROR_INVALID_ARGUMENT);
+
+    CHIP_ERROR err     = CHIP_NO_ERROR;
+    size_t appDataSize = GetAppDataSize(payload);
+
+    // To prevent workbuffer usage, appData size needs to be large enough to hold both the appData and the counter
+    VerifyOrReturnError(appData.size() >= sizeof(CounterType) + appDataSize, CHIP_ERROR_INVALID_ARGUMENT);
+
+    ByteSpan nonce         = payload.SubSpan(0, CHIP_CRYPTO_AEAD_NONCE_LENGTH_BYTES);
+    ByteSpan encryptedData = payload.SubSpan(CHIP_CRYPTO_AEAD_NONCE_LENGTH_BYTES, sizeof(CounterType) + appDataSize);
+    ByteSpan mic =
+        payload.SubSpan(CHIP_CRYPTO_AEAD_NONCE_LENGTH_BYTES + sizeof(CounterType) + appDataSize, CHIP_CRYPTO_AEAD_MIC_LENGTH_BYTES);
+
+    err = Crypto::AES_CCM_decrypt(encryptedData.data(), encryptedData.size(), nullptr, 0, mic.data(), mic.size(), key, nonce.data(),
+                                  nonce.size(), appData.data());
+
+    ReturnErrorOnFailure(err);
+
+    counter = Encoding::LittleEndian::Get32(appData.data());
+    // Shift to remove the counter from the appData
+    memmove(appData.data(), sizeof(CounterType) + appData.data(), appDataSize);
+
+    appData.reduce_size(appDataSize);
+    return err;
+}
+
+size_t CheckinMessage::GetAppDataSize(ByteSpan & payload)
+{
+    return (payload.size() <= sMinPayloadSize) ? 0 : payload.size() - sMinPayloadSize;
+}
+
+} // namespace SecureChannel
+} // namespace Protocols
+} // namespace chip

src/protocols/secure_channel/CheckinMessage.h

@@ -0,0 +1,90 @@
+/*
+ *    Copyright (c) 2020 Project CHIP Authors
+ *    All rights reserved.
+ *
+ *    Licensed 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.
+ */
+
+/**
+ *    @file
+ *      This file implements the Matter Checkin protocol.
+ */
+
+#pragma once
+
+#include <crypto/CHIPCryptoPAL.h>
+#include <lib/support/Span.h>
+#include <stdint.h>
+
+namespace chip {
+namespace Protocols {
+namespace SecureChannel {
+using namespace Crypto;
+
+using CounterType = uint32_t;
+
+/**
+ * @brief   Implement section 4.18.2 of the spec regarding
+ *          Check-in message payload
+ *
+ */
+class DLL_EXPORT CheckinMessage
+{
+public:
+    ~CheckinMessage();
+    /**
+     * @brief Generate Check-in Message payload
+     *
+     * @param key       Key with which to encrypt the check-in payload
+     * @param counter   Check-in counter
+     * @param appData   Application Data to incorporate within the Check-in message. Allowed to be empty.
+     * @param output    Buffer in Which to store the generated payload. SUFFICIENT SPACE MUST BE ALLOCATED by the caller
+     *                  Required Buffer Size is : GetCheckinPayloadSize(appData.size())
+     * @return CHIP_ERROR
+     */
+    static CHIP_ERROR GenerateCheckinMessagePayload(Crypto::Aes128KeyHandle & key, CounterType counter, const ByteSpan & appData,
+                                                    MutableByteSpan & output);
+
+    /**
+     * @brief Parse Check-in Message payload
+     *
+     * @param key       Key with which to decrypt the check-in payload
+     * @param payload   The received payload to decrypt and parse
+     * @param counter   The counter value retrieved from the payload
+     * @param appData   The optional application data decrypted. The size of appData must be at least the size of
+     *                  GetAppDataSize(payload) + sizeof(CounterType)
+     * @return CHIP_ERROR
+     */
+    static CHIP_ERROR ParseCheckinMessagePayload(Crypto::Aes128KeyHandle & key, ByteSpan & payload, CounterType & counter,
+                                                 MutableByteSpan & appData);
+
+    static inline size_t GetCheckinPayloadSize(size_t appDataSize) { return appDataSize + sMinPayloadSize; }
+
+    /**
+     * @brief Get the App Data Size
+     *
+     * @param payload   The undecrypted payload
+     * @return size_t size in byte of the application data from the payload
+     */
+    static size_t GetAppDataSize(ByteSpan & payload);
+
+    static constexpr uint16_t sMinPayloadSize =
+        CHIP_CRYPTO_AEAD_NONCE_LENGTH_BYTES + sizeof(CounterType) + CHIP_CRYPTO_AEAD_MIC_LENGTH_BYTES;
+
+    // Issue #28603
+    static constexpr uint16_t sMaxAppDataSize = 1024;
+};
+
+} // namespace SecureChannel
+} // namespace Protocols
+} // namespace chip

src/protocols/secure_channel/tests/BUILD.gn

@@ -13,6 +13,7 @@ chip_test_suite("tests") {
 
     # TODO - Fix Message Counter Sync to use group key
     #    "TestMessageCounterManager.cpp",
+    "TestCheckinMsg.cpp",
     "TestDefaultSessionResumptionStorage.cpp",
     "TestPASESession.cpp",
     "TestPairingSession.cpp",
@@ -22,6 +23,7 @@ chip_test_suite("tests") {
 
   public_deps = [
     "${chip_root}/src/credentials/tests:cert_test_vectors",
+    "${chip_root}/src/crypto/tests:tests_lib",
     "${chip_root}/src/lib/core",
     "${chip_root}/src/lib/support",
     "${chip_root}/src/lib/support:testing",