diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/marmotGroup/CreateGroupScreen.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/marmotGroup/CreateGroupScreen.kt
index a44befce5a..87df49bde0 100644
--- a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/marmotGroup/CreateGroupScreen.kt
+++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/marmotGroup/CreateGroupScreen.kt
@@ -41,6 +41,7 @@ import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.navigation.routes.Route
 import com.vitorpamplona.amethyst.ui.navigation.topbars.CreatingTopBar
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
+import com.vitorpamplona.quartz.nip01Core.core.toHexKey
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import kotlin.random.Random
@@ -61,7 +62,7 @@ fun CreateGroupScreen(
                 onPost = {
                     isCreating = true
                     scope.launch(Dispatchers.IO) {
-                        val nostrGroupId = Random.nextBytes(32).joinToString("") { "%02x".format(it) }
+                        val nostrGroupId = Random.nextBytes(32).toHexKey()
                         accountViewModel.createMarmotGroup(nostrGroupId)
                         if (groupName.isNotBlank()) {
                             accountViewModel.account.marmotGroupList
diff --git a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/marmot/mip00KeyPackages/KeyPackageRotationManager.kt b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/marmot/mip00KeyPackages/KeyPackageRotationManager.kt
index 196c8eeb31..33e3c81ea5 100644
--- a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/marmot/mip00KeyPackages/KeyPackageRotationManager.kt
+++ b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/marmot/mip00KeyPackages/KeyPackageRotationManager.kt
@@ -30,6 +30,7 @@ import com.vitorpamplona.quartz.marmot.mls.tree.Credential
 import com.vitorpamplona.quartz.marmot.mls.tree.LeafNode
 import com.vitorpamplona.quartz.marmot.mls.tree.LeafNodeSource
 import com.vitorpamplona.quartz.marmot.mls.tree.Lifetime
+import com.vitorpamplona.quartz.utils.TimeUtils
 
 /**
  * Manages KeyPackage creation and rotation lifecycle (MIP-00).
@@ -190,7 +191,7 @@ class KeyPackageRotationManager {
         identity: ByteArray,
         signingKey: ByteArray,
     ): LeafNode {
-        val now = System.currentTimeMillis() / 1000
+        val now = TimeUtils.now()
         val unsigned =
             LeafNode(
                 encryptionKey = encryptionKey,
diff --git a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/marmot/mls/group/MlsGroup.kt b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/marmot/mls/group/MlsGroup.kt
index def17d256d..d44b4a993e 100644
--- a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/marmot/mls/group/MlsGroup.kt
+++ b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/marmot/mls/group/MlsGroup.kt
@@ -55,6 +55,8 @@ import com.vitorpamplona.quartz.marmot.mls.tree.LeafNodeSource
 import com.vitorpamplona.quartz.marmot.mls.tree.Lifetime
 import com.vitorpamplona.quartz.marmot.mls.tree.RatchetTree
 import com.vitorpamplona.quartz.marmot.mls.tree.UpdatePathNode
+import com.vitorpamplona.quartz.nip01Core.core.toHexKey
+import com.vitorpamplona.quartz.utils.TimeUtils
 import com.vitorpamplona.quartz.utils.mac.MacInstance
 
 /**
@@ -170,11 +172,9 @@ class MlsGroup private constructor(
         pskId: ByteArray,
         psk: ByteArray,
     ) {
-        pskStore[pskId.toHexId()] = psk
+        pskStore[pskId.toHexKey()] = psk
     }
 
-    private fun ByteArray.toHexId(): String = joinToString("") { "%02x".format(it) }
-
     /**
      * Get the list of members (leaf index -> LeafNode).
      */
@@ -845,7 +845,7 @@ class MlsGroup private constructor(
         var pskSecret = ByteArray(MlsCryptoProvider.HASH_OUTPUT_LENGTH)
         for (pskProposal in pskProposals) {
             val pskValue =
-                pskStore[pskProposal.pskId.toHexId()]
+                pskStore[pskProposal.pskId.toHexKey()]
                     ?: ByteArray(MlsCryptoProvider.HASH_OUTPUT_LENGTH) // Unknown PSK = zeros
             pskSecret = MlsCryptoProvider.hkdfExtract(pskSecret, pskValue)
         }
@@ -990,7 +990,7 @@ class MlsGroup private constructor(
                 // Validate KeyPackage lifetime (RFC 9420 Section 10.1)
                 val lifetime = proposal.keyPackage.leafNode.lifetime
                 if (lifetime != null) {
-                    val now = System.currentTimeMillis() / 1000
+                    val now = TimeUtils.now()
                     require(now >= lifetime.notBefore && now <= lifetime.notAfter) {
                         "KeyPackage lifetime expired or not yet valid"
                     }