0.5.3 incompatible but better asymmetric keys id (both encryption and signing)

README.md

@@ -6,6 +6,12 @@ Cryptographic API works exactly the same and compiles to any platform supported
 
 All primitives meant to send over the network or store are `kotlinx.serialization` compatible, serializers included.
 
+# Important notes on upgrade
+
+Since version __0.5.*__ key identity calculation for asymmetric keys is updated
+to make it more safe for theoretic future attack on blake2b hashing. Key.id values
+are incompatible with older. Sorry for inconvenience.
+
 # Usage
 
 ```kotlin

build.gradle.kts

@@ -5,7 +5,7 @@ plugins {
 }
 
 group = "net.sergeych"
-version = "0.4.3"
+version = "0.5.3"
 
 repositories {
     mavenCentral()

src/commonMain/kotlin/net/sergeych/crypto2/KeyId.kt

@@ -23,7 +23,7 @@ import kotlinx.serialization.Serializable
  *            password, see above.
  */
 @Serializable
-data class KeyId(val id: BinaryId, val kdp: PBKD.Params?=null ) {
+data class KeyId(val id: BinaryId, val kdp: PBKD.Params? = null) {
 
     /**
      * Binary array representation of the [id], not including the [kdp]. Used in [SafeKeyExchange]
@@ -31,7 +31,7 @@ data class KeyId(val id: BinaryId, val kdp: PBKD.Params?=null ) {
      */
     val binaryTag: UByteArray by lazy { id.id }
 
-    val keymagic: KeysmagicNumber by lazy { KeysmagicNumber.entries[id.magic]}
+    val keymagic: KeysmagicNumber by lazy { KeysmagicNumber.entries[id.magic] }
 
     override fun equals(other: Any?): Boolean {
         if (this === other) return true
@@ -45,6 +45,17 @@ data class KeyId(val id: BinaryId, val kdp: PBKD.Params?=null ) {
 
     override fun toString() = id.toString()
 
-    constructor(magicNumber: KeysmagicNumber, keyData: UByteArray, kdp: PBKD.Params?=null)
-    : this(BinaryId.createFromUBytes(magicNumber.ordinal, blake2b3l(keyData)), kdp)
+    constructor(
+        magicNumber: KeysmagicNumber,
+        keyData: UByteArray,
+        kdp: PBKD.Params? = null,
+        donNotHash: Boolean = false,
+    )
+            : this(
+        BinaryId.createFromUBytes(
+            magicNumber.ordinal,
+            if (donNotHash) keyData else blake2b3l(keyData)
+        ),
+        kdp
+    )
 }

src/commonMain/kotlin/net/sergeych/crypto2/PublicKey.kt

@@ -69,4 +69,6 @@ class PublicKey(override val keyBytes: UByteArray) : UniversalKey(), EncryptingK
         randomFill: IntRange? = null,
     ): Asymmetric.Message =
         Asymmetric.createMessage(senderKey, this, WithFill.encode(plainData, randomFill))
+
+    override val id by lazy { KeyId(magic, keyBytes, null, true) }
 }

src/commonMain/kotlin/net/sergeych/crypto2/UniversalKey.kt

@@ -13,7 +13,7 @@ sealed class UniversalKey: KeyInstance {
     open val magic: KeysmagicNumber = KeysmagicNumber.Unknown
 
 
-    override val id by lazy { KeyId(magic, keyBytes) }
+    override val id by lazy { KeyId(magic, keyBytes, null) }
 
     // Important: id can be overridden, so we use it, not magic:
     open val label by lazy { id.keymagic.label }

src/commonMain/kotlin/net/sergeych/crypto2/VerifyingPublicKey.kt

@@ -24,4 +24,6 @@ class VerifyingPublicKey(override val keyBytes: UByteArray) : UniversalKey(), Ve
 
     @Transient
     override val magic: KeysmagicNumber = KeysmagicNumber.defaultVerifying
+
+    override val id by lazy { KeyId(magic, keyBytes, null, true) }
 }

src/commonTest/kotlin/KeysTest.kt

@@ -159,6 +159,11 @@ class KeysTest {
         val x2 = pk1.encryptMessage(plain, sk1).encoded
 
         assertFalse { x1 contentEquals x2 }
+
+        // public key ID should use key bytes instead
+        assertContentEquals(pk1.keyBytes, pk1.id.binaryTag.take(32).toUByteArray())
+        assertContentEquals(pk1.keyBytes, sk1.id.binaryTag.take(32).toUByteArray())
+
     }
     @Test
     fun asymmetricKeySerializationTest() = runTest {
@@ -261,5 +266,11 @@ class KeysTest {
         val dk2 = unpack<VerifyingPublicKey>(s2)
         assertEquals(k, dk1)
         assertEquals(k.verifyingKey, dk2)
+
+        // id for public/shared keys should be of the key itself to increase safety.
+        // not hashed!
+        assertContentEquals(k.verifyingKey.keyBytes, dk2.id.binaryTag.take(32).toUByteArray())
+        assertContentEquals(k.verifyingKey.keyBytes, dk1.id.binaryTag.take(32).toUByteArray())
+
     }
 }