diff --git a/README.md b/README.md
index ab5e936..b68b61c 100644
--- a/README.md
+++ b/README.md
@@ -8,6 +8,8 @@ All primitives meant to send over the network or store are `kotlinx.serializatio
 
 # Important notes on upgrade
 
+___Please upgrade to 0.7.1+___ as it has much more compact but not backward-compatible serialization format!
+
 Since version __0.5.*__ key identity calculation for asymmetric keys is updated
 to make it safer for theoretic future attack on blake2b hashing. Key.id values
 are incompatible with older. Sorry for inconvenience.
@@ -19,7 +21,7 @@ repositories {
   maven("https://gitea.sergeych.net/api/packages/SergeychWorks/maven")
 }
 dependencies {
-  import("net.sergeych:crypto2:0.5.8")  
+  import("net.sergeych:crypto2:0.7.1-SNAPSHOT")  
 }
 ```
 
diff --git a/build.gradle.kts b/build.gradle.kts
index b6532d4..6700b04 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -9,7 +9,7 @@ plugins {
 }
 
 group = "net.sergeych"
-version = "0.6.3-SNAPSHOT"
+version = "0.7.1-SNAPSHOT"
 
 repositories {
     mavenCentral()
diff --git a/src/commonMain/kotlin/net/sergeych/crypto2/SigningSecretKey.kt b/src/commonMain/kotlin/net/sergeych/crypto2/SigningSecretKey.kt
index f2a341e..8ba1241 100644
--- a/src/commonMain/kotlin/net/sergeych/crypto2/SigningSecretKey.kt
+++ b/src/commonMain/kotlin/net/sergeych/crypto2/SigningSecretKey.kt
@@ -30,6 +30,7 @@ class SigningSecretKey(
     override fun seal(message: UByteArray, expiresAt: Instant?): Seal =
         Seal.create(this, message, now(), expiresAt)
 
+    @Transient
     override val id: KeyId = verifyingKey.id
 
     override val label: String
diff --git a/src/commonTest/kotlin/KeysTest.kt b/src/commonTest/kotlin/KeysTest.kt
index 109f1c1..9ec6030 100644
--- a/src/commonTest/kotlin/KeysTest.kt
+++ b/src/commonTest/kotlin/KeysTest.kt
@@ -3,6 +3,8 @@ import com.ionspin.kotlin.crypto.util.encodeToUByteArray
 import kotlinx.coroutines.test.runTest
 import kotlinx.serialization.encodeToString
 import kotlinx.serialization.json.Json
+import net.sergeych.bipack.BipackDecoder
+import net.sergeych.bipack.BipackEncoder
 import net.sergeych.crypto2.*
 import net.sergeych.tools.bipack
 import net.sergeych.tools.biunpack
@@ -390,4 +392,28 @@ class KeysTest {
         assertNull(Container.decrypt<String>(bytes, kr1))
         assertEquals(data, Container.decrypt<String>(bytes, kr2))
     }
+
+    @Test
+    fun testEncodedSizes() = runTest {
+        initCrypto()
+        val x = SigningSecretKey.new()
+//        println("key bytes: ${x.keyBytes.size}:\n${x.keyBytes.toDump()}")
+        val y = BipackEncoder.encode(x)
+//        println("packed: ${y.size}: ${y.toDump()}")
+        assertTrue { x.keyBytes.size + 5 > y.size }
+        assertEquals(x, BipackDecoder.decode<SigningSecretKey>(y))
+        assertContentEquals(x.keyBytes, BipackDecoder.decode<SigningSecretKey>(y).keyBytes)
+    }
+
+    @Test
+    fun testEncodedSizes2() = runTest {
+        initCrypto()
+        val x = SecretKey.new()
+//        println("key bytes: ${x.keyBytes.size}:\n${x.keyBytes.toDump()}")
+        val y = BipackEncoder.encode(x)
+//        println("packed: ${y.size}: ${y.toDump()}")
+        assertTrue { x.keyBytes.size + 5 > y.size }
+        assertEquals(x, BipackDecoder.decode<SecretKey>(y))
+        assertContentEquals(x.keyBytes, BipackDecoder.decode<SecretKey>(y).keyBytes)
+    }
 }