Adding crypto_auth

multiplatform-crypto-libsodium-bindings/src/commonMain/kotlin/com.ionspin.kotlin.crypto/auth/Auth.kt

@@ -0,0 +1,32 @@
+package com.ionspin.kotlin.crypto.auth
+
+/**
+ * Created by Ugljesa Jovanovic
+ * ugljesa.jovanovic@ionspin.com
+ * on 30-Aug-2020
+ */
+
+val crypto_auth_BYTES = 32
+val crypto_auth_KEYBYTES = 32
+
+val crypto_auth_hmacsha256_KEYBYTES = 32
+val crypto_auth_hmacsha256_BYTES =32
+
+val crypto_auth_hmacsha512_KEYBYTES = 32
+val crypto_auth_hmacsha512_BYTES = 64
+
+expect object Auth {
+
+    fun authKeygen() : UByteArray
+    fun auth(message: UByteArray, key: UByteArray) : UByteArray
+    fun authVerify(mac: UByteArray, message: UByteArray, key: UByteArray) : Boolean
+
+    fun authHmacSha256Keygen() : UByteArray
+    fun authHmacSha256(message: UByteArray, key: UByteArray) : UByteArray
+    fun authHmacSha256Verify(mac: UByteArray, message: UByteArray, key: UByteArray) : Boolean
+
+    fun authHmacSha512Keygen() : UByteArray
+    fun authHmacSha512(message: UByteArray, key: UByteArray) : UByteArray
+    fun authHmacSha512Verify(mac: UByteArray, message: UByteArray, key: UByteArray) : Boolean
+
+}