implement common class, refactor HMAC

src/commonMain/kotlin/com/infendro/mac/HMAC.kt

@@ -1,45 +1,33 @@
 package com.infendro.mac
 
-import com.infendro.hash.*
-import kotlin.experimental.xor
+import com.infendro.bytearray.padEnd
+import com.infendro.hash.HashFunction
 
 class HMAC(
     val function: HashFunction,
-) {
-    val block: Int
-        get() = when (function) {
-            MD5, SHA1, SHA224, SHA256 -> 64
-            SHA384, SHA512 -> 128
-        }
+) : MAC() {
+    override val bytes: Int
+        get() = function.bytes
 
-    fun hash(
-        key: ByteArray,
-        value: ByteArray,
-    ): ByteArray {
+    override fun hash(
+        key: UByteArray,
+        value: UByteArray,
+    ): UByteArray {
         val paddedKey = pad(key)
 
-        val innerKey = paddedKey.map { it xor 0x36 }.toByteArray()
-        val outerKey = paddedKey.map { it xor 0x5C }.toByteArray()
+        val innerKey = paddedKey.map { it xor 0x36U }.toUByteArray()
+        val outerKey = paddedKey.map { it xor 0x5CU }.toUByteArray()
 
         return function.hash(outerKey + function.hash(innerKey + value))
     }
 
     private fun pad(
-        key: ByteArray,
-    ): ByteArray {
-        if (key.size > block) {
-            return function.hash(key)
+        key: UByteArray,
+    ): UByteArray {
+        return when {
+            key.size > function.block -> function.hash(key)
+            key.size < function.block -> key.padEnd(function.block, 0x00U)
+            else -> key
         }
-
-        if (key.size < block) {
-            return buildList {
-                addAll(key.toList())
-                repeat(block - size) {
-                    add(0x00)
-                }
-            }.toByteArray()
-        }
-
-        return key
     }
 }