[msg] Fix counter init. (#12948)

src/transport/MessageCounter.cpp

@@ -29,7 +29,7 @@ namespace chip {
 
 void GlobalUnencryptedMessageCounter::Init()
 {
- value = Crypto::GetRandU32();
+ mValue = Crypto::GetRandU32();
 }
 
 CHIP_ERROR GlobalEncryptedMessageCounter::Init()

src/transport/MessageCounter.h

@@ -56,20 +56,20 @@ class MessageCounter
 class GlobalUnencryptedMessageCounter : public MessageCounter
 {
 public:
- GlobalUnencryptedMessageCounter() : value(0) {}
+ GlobalUnencryptedMessageCounter() : mValue(0) {}
 
  void Init();
 
  Type GetType() override { return GlobalUnencrypted; }
- uint32_t Value() override { return value; }
+ uint32_t Value() override { return mValue; }
  CHIP_ERROR Advance() override
  {
- ++value;
+ ++mValue;
  return CHIP_NO_ERROR;
  }
 
 private:
- uint32_t value;
+ uint32_t mValue;
 };
 
 class GlobalEncryptedMessageCounter : public MessageCounter
@@ -88,44 +88,45 @@ class GlobalEncryptedMessageCounter : public MessageCounter
 #else
  struct FakePersistedCounter
  {
- FakePersistedCounter() : value(0) {}
+ FakePersistedCounter() : mValue(0) {}
  CHIP_ERROR Init(chip::Platform::PersistedStorage::Key aId, uint32_t aEpoch) { return CHIP_NO_ERROR; }
 
- uint32_t GetValue() { return value; }
+ uint32_t GetValue() { return mValue; }
  CHIP_ERROR Advance()
  {
- ++value;
+ ++mValue;
  return CHIP_NO_ERROR;
  }
 
  private:
- uint32_t value;
+ uint32_t mValue;
  } persisted;
 #endif
 };
 
 class LocalSessionMessageCounter : public MessageCounter
 {
 public:
- static constexpr uint32_t kInitialValue  = 1; ///< Used for initializing peer counter
+ static constexpr uint32_t kInitialSyncValue = 0; ///< Used for initializing peer counter
  static constexpr uint32_t kMessageCounterRandomInitMask = 0x0FFFFFF; ///< 28-bit mask
 
  /**
- * Initialize a local message counter with random value between [0, 2^28-1]. This increases the difficulty of traffic analysis
- * attacks by making it harder to determine how long a particular session has been open.
+ * Initialize a local message counter with random value between [1, 2^28]. This increases the difficulty of traffic analysis
+ * attacks by making it harder to determine how long a particular session has been open. The initial counter is always 1 or
+ * higher to guarantee first message is always greater than initial peer counter set to 0.
  */
- LocalSessionMessageCounter() { value = Crypto::GetRandU32() & kMessageCounterRandomInitMask; }
+ LocalSessionMessageCounter() { mValue = (Crypto::GetRandU32() & kMessageCounterRandomInitMask) + 1; }
 
  Type GetType() override { return Session; }
- uint32_t Value() override { return value; }
+ uint32_t Value() override { return mValue; }
  CHIP_ERROR Advance() override
  {
- ++value;
+ ++mValue;
  return CHIP_NO_ERROR;
  }
 
 private:
- uint32_t value;
+ uint32_t mValue;
 };
 
 } // namespace chip

src/transport/PairingSession.h

@@ -86,7 +86,7 @@ class DLL_EXPORT PairingSession
  virtual uint32_t GetPeerCounter()
  {
  // TODO(#6652): This is a stub implementation, should be replaced by the real one when CASE and PASE is completed
- return LocalSessionMessageCounter::kInitialValue;
+ return LocalSessionMessageCounter::kInitialSyncValue;
  }
 
  /**