fix(mobile): encode platform did keys as raw public keys

Author: szijpeter

waltid-libraries/crypto/waltid-crypto/src/androidDeviceTest/kotlin/id/walt/crypto/AndroidKeyTest.kt

@@ -45,6 +45,17 @@ class AndroidKeyTest {
             assertFailsWith<IllegalStateException>("public platform key should not sign for $type") {
                 publicKey.signRaw("nope".encodeToByteArray())
             }
+
+            val publicKeyRepresentation = publicKey.getPublicKeyRepresentation()
+            when (type) {
+                KeyType.secp256r1 -> assertEquals(65, publicKeyRepresentation.size)
+                KeyType.secp384r1 -> assertEquals(97, publicKeyRepresentation.size)
+                KeyType.secp521r1 -> assertEquals(133, publicKeyRepresentation.size)
+                else -> Unit
+            }
+            if (type != KeyType.RSA) {
+                assertEquals(0x04, publicKeyRepresentation.first().toInt())
+            }
         }
     }
 

waltid-libraries/crypto/waltid-crypto/src/androidMain/kotlin/id/walt/crypto/AndroidKey.kt

@@ -100,7 +100,7 @@ sealed class AndroidKey : Key() {
         }
 
         override suspend fun getPublicKey(): Key = Platform(options, hasPrivateKey = false)
-        override suspend fun getPublicKeyRepresentation(): ByteArray = signer().publicKey.encodeToTlv().derEncoded
+        override suspend fun getPublicKeyRepresentation(): ByteArray = signer().publicKey.iosEncoded
         override suspend fun getMeta(): KeyMeta = JwkKeyMeta(getKeyId())
         override suspend fun deleteKey(): Boolean = runCatching {
             AndroidKeyStoreProvider.deleteSigningKey(options.kid).getOrThrow()

waltid-libraries/crypto/waltid-crypto/src/iosMain/kotlin/id/walt/crypto/IosKey.kt

@@ -110,7 +110,7 @@ sealed class IosKey : Key() {
         }
 
         override suspend fun getPublicKey(): Key = Platform(options, hasPrivateKey = false)
-        override suspend fun getPublicKeyRepresentation(): ByteArray = signer().publicKey.encodeToTlv().derEncoded
+        override suspend fun getPublicKeyRepresentation(): ByteArray = signer().publicKey.iosEncoded
         override suspend fun getMeta(): KeyMeta = JwkKeyMeta(getKeyId())
         override suspend fun deleteKey(): Boolean = runCatching {
             IosKeychainProvider.deleteSigningKey(options.kid).getOrThrow()