small refactor

src/commonMain/kotlin/com/infendro/kdf/PBKDF2.kt

@@ -9,7 +9,6 @@ import com.infendro.mac.HMAC
 class PBKDF2(
     function: HashFunction,
 ) {
-    private val size = function.bytes
     private val hmac = HMAC(function)
 
     fun hash(
@@ -18,23 +17,18 @@ class PBKDF2(
         iterations: Int,
         length: Int,
     ): ByteArray {
-        val key = mutableListOf<Byte>()
+        val key = buildList {
+            for (i in 1..(length + size - 1) / size) {
+                val input = salt + i.toUInt().toByteArray()
 
-        for (i in 1..(length + size - 1) / size) {
-            val input = salt + i.toUInt().toByteArray()
+                var u = hmac.hash(value, input)
+                var result = u
+                repeat(iterations - 1) {
+                    u = hmac.hash(value, u)
+                    result = result xor u
+                }
 
-            var u = hmac.hash(value, input)
-            var result = u
-            repeat(iterations - 1) {
-                u = hmac.hash(value, u)
-                result = result xor u
-            }
-
-            key.addAll(result)
-
-            if (key.size >= length) {
-                println(key.size)
-                break
+                addAll(result)
             }
         }