Implemeting _stream_ primitives, at elast the ones available in lazy sodium

multiplatform-crypto-libsodium-bindings/src/commonMain/kotlin/com.ionspin.kotlin.crypto/stream/Stream.kt

@@ -0,0 +1,21 @@
+package com.ionspin.kotlin.crypto.stream
+
+/**
+ * Created by Ugljesa Jovanovic
+ * ugljesa.jovanovic@ionspin.com
+ * on 11-Oct-2020
+ */
+const val crypto_stream_chacha20_KEYBYTES = 32
+const val crypto_stream_chacha20_NONCEBYTES = 8
+const val crypto_stream_chacha20_ietf_KEYBYTES = 32
+const val crypto_stream_chacha20_ietf_NONCEBYTES = 12
+
+
+expect object Stream {
+    fun chacha20(clen: Int, nonce: UByteArray, key: UByteArray) : UByteArray
+    fun chacha20IetfXor(message : UByteArray, nonce: UByteArray, key: UByteArray) : UByteArray
+    fun chacha20IetfXorIc(message : UByteArray, nonce: UByteArray, initialCounter: ULong, key: UByteArray) : UByteArray
+    fun chacha20Keygen() : UByteArray
+    fun chacha20Xor(message : UByteArray, nonce: UByteArray, key: UByteArray) : UByteArray
+    fun chacha20XorIc(message : UByteArray, nonce: UByteArray, initialCounter: ULong, key: UByteArray) : UByteArray
+}