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fix: use CSPRNG for heartbeat intervals #685

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Merged
callebtc merged 1 commit into from
Mar 25, 2026
Merged

fix: use CSPRNG for heartbeat intervals #685

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11 changes: 8 additions & 3 deletions app/src/main/java/com/bitchat/android/ui/GeohashViewModel.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,8 @@ import java.util.Date
import kotlinx.coroutines.flow.collectLatest
import kotlinx.coroutines.isActive
import kotlinx.coroutines.Dispatchers
import java.security.SecureRandom
import kotlin.random.asKotlinRandom

class GeohashViewModel(
application: Application,
Expand All @@ -37,7 +39,10 @@ class GeohashViewModel(
private val notificationManager: NotificationManager
) : AndroidViewModel(application), DefaultLifecycleObserver {

companion object { private const val TAG = "GeohashViewModel" }
companion object {
private const val TAG = "GeohashViewModel"
private val secureRandom = SecureRandom().asKotlinRandom()
}

private val repo = GeohashRepository(application, state, dataManager)
private val subscriptionManager = NostrSubscriptionManager(application, viewModelScope)
Expand Down Expand Up @@ -123,14 +128,14 @@ class GeohashViewModel(
// If channels change (e.g. user moves), collectLatest cancels this loop and starts a new one immediately
while (true) {
// Randomize loop interval (40-80s, average 60s)
val loopInterval = kotlin.random.Random.nextLong(40000L, 80000L)
val loopInterval = secureRandom.nextLong(40000L, 80000L)
var timeSpent = 0L

try {
Log.v(TAG, "💓 Broadcasting global presence to ${targetGeohashes.size} channels")
targetGeohashes.forEach { geohash ->
// Decorrelate individual broadcasts with random delay (1s-5s)
val stepDelay = kotlin.random.Random.nextLong(1000L, 10000L)
val stepDelay = secureRandom.nextLong(1000L, 10000L)
delay(stepDelay)
timeSpent += stepDelay

Expand Down
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