upgrade

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

@@ -5,8 +5,20 @@ interface KDF {
     val bits: Int
         get() = bytes * 8
 
-    fun hash(
-        value: UByteArray,
-        salt: UByteArray,
-    ): UByteArray
+    fun hashInto(value: ByteArray, salt: ByteArray, destination: ByteArray, destinationOffset: Int = 0)
+
+    fun hashInto(value: ByteArray, salt: ByteArray, destination: UByteArray, destinationOffset: Int = 0) =
+        hashInto(value, salt, destination.asByteArray(), destinationOffset)
+
+    fun hashInto(value: UByteArray, salt: UByteArray, destination: ByteArray, destinationOffset: Int = 0) =
+        hashInto(value.asByteArray(), salt.asByteArray(), destination, destinationOffset)
+
+    fun hashInto(value: UByteArray, salt: UByteArray, destination: UByteArray, destinationOffset: Int = 0) =
+        hashInto(value.asByteArray(), salt.asByteArray(), destination.asByteArray(), destinationOffset)
+
+    fun hash(value: ByteArray, salt: ByteArray): ByteArray =
+        ByteArray(bytes).also { hashInto(value, salt, it) }
+
+    fun hash(value: UByteArray, salt: UByteArray): UByteArray =
+        UByteArray(bytes).also { hashInto(value, salt, it) }
 }

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

@@ -1,10 +1,10 @@
 package com.infendro.kdf
 
-import com.infendro.bytearray.toUByteArray
-import com.infendro.bytearray.xor
+import com.infendro.bytes.bytearray.xorInto
+import com.infendro.bytes.int.copyInto
 import com.infendro.hash.HashFunction
+import com.infendro.kdf.util.ceilDiv
 import com.infendro.mac.HMAC
-import kotlin.math.min
 
 class PBKDF2(
     override val bytes: Int,
@@ -16,34 +16,25 @@ class PBKDF2(
         require(iterations > 0)
     }
 
-    private val mac = HMAC(function)
+    private val hmac = HMAC(function)
 
-    override fun hash(
-        value: UByteArray,
-        salt: UByteArray,
-    ): UByteArray {
-        return buildList {
-            var i = 1
-            while (size < bytes) {
-                addAll(
-                    f(value, salt, i)
-                        .sliceArray(0..<min(bytes - size, mac.bytes))
-                )
-                i++
-            }
-        }.toUByteArray()
-    }
+    override fun hashInto(value: ByteArray, salt: ByteArray, destination: ByteArray, destinationOffset: Int) {
+        val buffer = ByteArray(hmac.bytes)
 
-    private fun f(
-        value: UByteArray,
-        salt: UByteArray,
-        iteration: Int,
-    ): UByteArray {
-        return buildList {
-            add(mac.hash(value, salt + iteration.toUByteArray()))
+        for (iteration in 1..bytes.ceilDiv(hmac.bytes)) {
+            val offset = (iteration - 1) * hmac.bytes
+            val block = minOf(bytes - offset, hmac.bytes)
+
+            val s = ByteArray(salt.size + 4)
+            salt.copyInto(s)
+            iteration.copyInto(s, salt.size)
+
+            hmac.hashInto(value, s, buffer)
+            buffer.copyInto(destination, destinationOffset + offset, endIndex = block)
             repeat(iterations - 1) {
-                add(mac.hash(value, last()))
+                hmac.hashInto(value, buffer, buffer)
+                buffer.xorInto(destination, destinationOffset + offset, endIndex = block)
             }
-        }.reduce { acc, bytes -> acc xor bytes }
+        }
     }
 }

src/commonMain/kotlin/com/infendro/kdf/util/Math.kt

@@ -0,0 +1,4 @@
+package com.infendro.kdf.util
+
+internal fun Int.ceilDiv(n: Int): Int =
+    (this + n - 1) / n