diff --git a/library/xof/api/xof.api b/library/xof/api/xof.api
index 56fd791..d8ece80 100644
--- a/library/xof/api/xof.api
+++ b/library/xof/api/xof.api
@@ -1,14 +1,26 @@
+public abstract interface class org/kotlincrypto/core/xof/ReKeyableXofAlgorithm : org/kotlincrypto/core/xof/XofAlgorithm {
+	public abstract fun reset ([B)V
+}
+
 public abstract class org/kotlincrypto/core/xof/Xof : org/kotlincrypto/core/Algorithm, org/kotlincrypto/core/Copyable, org/kotlincrypto/core/Resettable, org/kotlincrypto/core/Updatable {
+	public static final field Companion Lorg/kotlincrypto/core/xof/Xof$Companion;
+	protected final field delegate Lorg/kotlincrypto/core/xof/XofAlgorithm;
+	public synthetic fun <init> (Lorg/kotlincrypto/core/xof/XofAlgorithm;Lkotlin/jvm/internal/DefaultConstructorMarker;)V
 	protected abstract fun newReader ()Lorg/kotlincrypto/core/xof/Xof$Reader;
 	public final fun reader ()Lorg/kotlincrypto/core/xof/Xof$Reader;
 	public final fun reader (Z)Lorg/kotlincrypto/core/xof/Xof$Reader;
 	public static synthetic fun reader$default (Lorg/kotlincrypto/core/xof/Xof;ZILjava/lang/Object;)Lorg/kotlincrypto/core/xof/Xof$Reader;
+	public static final fun reset (Lorg/kotlincrypto/core/xof/Xof;[B)V
 	public final fun toString ()Ljava/lang/String;
 	public final fun use (Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public final fun use (ZLkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public static synthetic fun use$default (Lorg/kotlincrypto/core/xof/Xof;ZLkotlin/jvm/functions/Function1;ILjava/lang/Object;)Ljava/lang/Object;
 }
 
+public final class org/kotlincrypto/core/xof/Xof$Companion {
+	public final fun reset (Lorg/kotlincrypto/core/xof/Xof;[B)V
+}
+
 public abstract class org/kotlincrypto/core/xof/Xof$Reader {
 	public fun <init> (Lorg/kotlincrypto/core/xof/Xof;)V
 	public final fun bytesRead ()J
@@ -43,7 +55,6 @@ protected abstract class org/kotlincrypto/core/xof/XofFactory$XofDelegate : org/
 	protected fun <init> (Lorg/kotlincrypto/core/xof/XofFactory;Lorg/kotlincrypto/core/xof/XofAlgorithm;)V
 	public fun algorithm ()Ljava/lang/String;
 	public final fun equals (Ljava/lang/Object;)Z
-	protected final fun getDelegate ()Lorg/kotlincrypto/core/xof/XofAlgorithm;
 	public final fun hashCode ()I
 	protected final fun newReader ()Lorg/kotlincrypto/core/xof/Xof$Reader;
 	protected abstract fun newReader (Lorg/kotlincrypto/core/xof/XofAlgorithm;)Lorg/kotlincrypto/core/xof/Xof$Reader;
diff --git a/library/xof/api/xof.klib.api b/library/xof/api/xof.klib.api
index 76cca6b..3ae2fbb 100644
--- a/library/xof/api/xof.klib.api
+++ b/library/xof/api/xof.klib.api
@@ -6,6 +6,10 @@
 // - Show declarations: true
 
 // Library unique name: <org.kotlincrypto.core:xof>
+abstract interface org.kotlincrypto.core.xof/ReKeyableXofAlgorithm : org.kotlincrypto.core.xof/XofAlgorithm { // org.kotlincrypto.core.xof/ReKeyableXofAlgorithm|null[0]
+    abstract fun reset(kotlin/ByteArray) // org.kotlincrypto.core.xof/ReKeyableXofAlgorithm.reset|reset(kotlin.ByteArray){}[0]
+}
+
 abstract interface org.kotlincrypto.core.xof/XofAlgorithm : org.kotlincrypto.core/Algorithm // org.kotlincrypto.core.xof/XofAlgorithm|null[0]
 
 abstract class <#A: org.kotlincrypto.core.xof/XofAlgorithm> org.kotlincrypto.core.xof/XofFactory { // org.kotlincrypto.core.xof/XofFactory|null[0]
@@ -14,9 +18,6 @@ abstract class <#A: org.kotlincrypto.core.xof/XofAlgorithm> org.kotlincrypto.cor
     abstract inner class XofDelegate : org.kotlincrypto.core.xof/Xof<#A>, org.kotlincrypto.core/Algorithm, org.kotlincrypto.core/Resettable, org.kotlincrypto.core/Updatable { // org.kotlincrypto.core.xof/XofFactory.XofDelegate|null[0]
         constructor <init>(#A) // org.kotlincrypto.core.xof/XofFactory.XofDelegate.<init>|<init>(2:0){}[0]
 
-        final val delegate // org.kotlincrypto.core.xof/XofFactory.XofDelegate.delegate|{}delegate[0]
-            final fun <get-delegate>(): #A // org.kotlincrypto.core.xof/XofFactory.XofDelegate.delegate.<get-delegate>|<get-delegate>(){}[0]
-
         abstract fun newReader(#A): org.kotlincrypto.core.xof/Xof.Reader<#A> // org.kotlincrypto.core.xof/XofFactory.XofDelegate.newReader|newReader(2:0){}[0]
         final fun equals(kotlin/Any?): kotlin/Boolean // org.kotlincrypto.core.xof/XofFactory.XofDelegate.equals|equals(kotlin.Any?){}[0]
         final fun hashCode(): kotlin/Int // org.kotlincrypto.core.xof/XofFactory.XofDelegate.hashCode|hashCode(){}[0]
@@ -30,7 +31,10 @@ abstract class <#A: org.kotlincrypto.core.xof/XofAlgorithm> org.kotlincrypto.cor
 }
 
 sealed class <#A: org.kotlincrypto.core.xof/XofAlgorithm> org.kotlincrypto.core.xof/Xof : org.kotlincrypto.core/Algorithm, org.kotlincrypto.core/Copyable<org.kotlincrypto.core.xof/Xof<#A>>, org.kotlincrypto.core/Resettable, org.kotlincrypto.core/Updatable { // org.kotlincrypto.core.xof/Xof|null[0]
-    constructor <init>() // org.kotlincrypto.core.xof/Xof.<init>|<init>(){}[0]
+    constructor <init>(#A) // org.kotlincrypto.core.xof/Xof.<init>|<init>(1:0){}[0]
+
+    final val delegate // org.kotlincrypto.core.xof/Xof.delegate|{}delegate[0]
+        final fun <get-delegate>(): #A // org.kotlincrypto.core.xof/Xof.delegate.<get-delegate>|<get-delegate>(){}[0]
 
     abstract fun newReader(): org.kotlincrypto.core.xof/Xof.Reader<#A> // org.kotlincrypto.core.xof/Xof.newReader|newReader(){}[0]
     final fun <#A1: kotlin/Any?> use(kotlin/Boolean =..., kotlin/Function1<org.kotlincrypto.core.xof/Xof.Reader<#A>, #A1>): #A1 // org.kotlincrypto.core.xof/Xof.use|use(kotlin.Boolean;kotlin.Function1<org.kotlincrypto.core.xof.Xof.Reader<1:0>,0:0>){0§<kotlin.Any?>}[0]
@@ -55,6 +59,10 @@ sealed class <#A: org.kotlincrypto.core.xof/XofAlgorithm> org.kotlincrypto.core.
         final fun toString(): kotlin/String // org.kotlincrypto.core.xof/Xof.Reader.toString|toString(){}[0]
     }
 
+    final object Companion { // org.kotlincrypto.core.xof/Xof.Companion|null[0]
+        final fun <#A2: org.kotlincrypto.core.xof/ReKeyableXofAlgorithm> (org.kotlincrypto.core.xof/Xof<#A2>).reset(kotlin/ByteArray) // org.kotlincrypto.core.xof/Xof.Companion.reset|reset@org.kotlincrypto.core.xof.Xof<0:0>(kotlin.ByteArray){0§<org.kotlincrypto.core.xof.ReKeyableXofAlgorithm>}[0]
+    }
+
     final object Utils { // org.kotlincrypto.core.xof/Xof.Utils|null[0]
         final fun leftEncode(kotlin/Int): kotlin/ByteArray // org.kotlincrypto.core.xof/Xof.Utils.leftEncode|leftEncode(kotlin.Int){}[0]
         final fun leftEncode(kotlin/Int, kotlin/Int): kotlin/ByteArray // org.kotlincrypto.core.xof/Xof.Utils.leftEncode|leftEncode(kotlin.Int;kotlin.Int){}[0]
diff --git a/library/xof/src/commonMain/kotlin/org/kotlincrypto/core/xof/Xof.kt b/library/xof/src/commonMain/kotlin/org/kotlincrypto/core/xof/Xof.kt
index 0c47215..f060fa9 100644
--- a/library/xof/src/commonMain/kotlin/org/kotlincrypto/core/xof/Xof.kt
+++ b/library/xof/src/commonMain/kotlin/org/kotlincrypto/core/xof/Xof.kt
@@ -18,6 +18,7 @@
 package org.kotlincrypto.core.xof
 
 import org.kotlincrypto.core.*
+import kotlin.jvm.JvmField
 import kotlin.jvm.JvmName
 import kotlin.jvm.JvmOverloads
 import kotlin.jvm.JvmStatic
@@ -52,7 +53,22 @@ import kotlin.jvm.JvmStatic
  * @see [reader]
  * @see [Reader]
  * */
-public sealed class Xof<A: XofAlgorithm>: Algorithm, Copyable<Xof<A>>, Resettable, Updatable {
+public sealed class Xof<A: XofAlgorithm>(
+    @JvmField
+    protected val delegate: A,
+): Algorithm, Copyable<Xof<A>>, Resettable, Updatable {
+
+    public companion object {
+
+        /**
+         * Helper to provide access to the instance backing [Xof], if said instance
+         * can be re-keyed (such as a [org.kotlincrypto.core.mac.Mac]).
+         *
+         * @throws [IllegalArgumentException] if [newKey] is unacceptable.
+         * */
+        @JvmStatic
+        public fun <A: ReKeyableXofAlgorithm> Xof<A>.reset(newKey: ByteArray) { delegate.reset(newKey) }
+    }
 
     /**
      * Takes a snapshot of the current [Xof]'s state and produces
@@ -298,5 +314,4 @@ public sealed class Xof<A: XofAlgorithm>: Algorithm, Copyable<Xof<A>>, Resettabl
 
     /** @suppress */
     public final override fun toString(): String = "Xof[${algorithm()}]@${hashCode()}"
-
 }
diff --git a/library/xof/src/commonMain/kotlin/org/kotlincrypto/core/xof/XofAlgorithm.kt b/library/xof/src/commonMain/kotlin/org/kotlincrypto/core/xof/XofAlgorithm.kt
index b44845d..ed3da83 100644
--- a/library/xof/src/commonMain/kotlin/org/kotlincrypto/core/xof/XofAlgorithm.kt
+++ b/library/xof/src/commonMain/kotlin/org/kotlincrypto/core/xof/XofAlgorithm.kt
@@ -22,3 +22,22 @@ import org.kotlincrypto.core.Algorithm
  * which supports Extendable-Output Functions (XOFs).
  * */
 public interface XofAlgorithm: Algorithm
+
+/**
+ * Extended functionality, specifically for a [Xof] who's backing instance
+ * is a [org.kotlincrypto.core.mac.Mac].
+ *
+ *
+ * @see [Xof.Companion.reset]
+ * */
+public interface ReKeyableXofAlgorithm: XofAlgorithm {
+
+    /**
+     * Resets and re-initializes the instance with the provided [newKey]
+     *
+     * This is useful if wanting to clear the key before de-referencing.
+     *
+     * @throws [IllegalArgumentException] if [newKey] is unacceptable.
+     * */
+    public fun reset(newKey: ByteArray)
+}
diff --git a/library/xof/src/commonMain/kotlin/org/kotlincrypto/core/xof/XofFactory.kt b/library/xof/src/commonMain/kotlin/org/kotlincrypto/core/xof/XofFactory.kt
index 96f968e..da89372 100644
--- a/library/xof/src/commonMain/kotlin/org/kotlincrypto/core/xof/XofFactory.kt
+++ b/library/xof/src/commonMain/kotlin/org/kotlincrypto/core/xof/XofFactory.kt
@@ -54,9 +54,7 @@ public abstract class XofFactory<A: XofAlgorithm> public constructor() {
      * */
     protected abstract inner class XofDelegate
     @Throws(ClassCastException::class, IllegalArgumentException::class)
-    protected constructor(
-        protected val delegate: A,
-    ) : Xof<A>(),
+    protected constructor(delegate: A) : Xof<A>(delegate),
         Algorithm by delegate,
         Resettable by delegate as Resettable,
         Updatable by delegate as Updatable