diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index bbbe93a..786e675 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -1,8 +1,8 @@
 [versions]
 infendro = "1.1.0"
 kotlin = "2.3.0"
-bytes = "1.4.0"
-hash = "1.6.0"
+bytes = "1.4.1"
+hash = "1.7.0"
 
 [plugins]
 infendro = { id = "com.infendro.plugin", version.ref = "infendro" }
diff --git a/src/commonMain/kotlin/com/infendro/mac/HMAC.kt b/src/commonMain/kotlin/com/infendro/mac/HMAC.kt
index 3e42e7d..dd9b10b 100644
--- a/src/commonMain/kotlin/com/infendro/mac/HMAC.kt
+++ b/src/commonMain/kotlin/com/infendro/mac/HMAC.kt
@@ -5,29 +5,59 @@ import com.infendro.hash.HashFunction
 
 class HMAC(
     val function: HashFunction,
-) : MAC {
-    override val bytes: Int
-        get() = function.bytes
+) : MAC(function.bytes) {
+    private var initialized = false
+    private val innerPadding: ByteArray = ByteArray(function.block)
+    private val outerPadding: ByteArray = ByteArray(function.block)
+    private val inner: ByteArray = ByteArray(function.bytes)
 
-    override fun hashInto(key: ByteArray, value: ByteArray, destination: ByteArray, destinationOffset: Int) {
-        val paddedKey = pad(key)
-        val inner = ByteArray(function.block + value.size).also {
-            paddedKey.xorInto(0x36, it)
-            value.copyInto(it, function.block)
-        }
-        val outer = ByteArray(function.block + function.bytes).also {
-            paddedKey.xorInto(0x5C, it)
-            function.hashInto(inner, it, function.block)
-        }
-        function.hashInto(outer, destination, destinationOffset)
+    override fun reset() {
+        function.reset()
+        initialized = false
+        innerPadding.fill(0x00)
+        outerPadding.fill(0x00)
+    }
+
+    override fun init(key: ByteArray) {
+        val padded = pad(key)
+        padded.xorInto(0x36, innerPadding)
+        padded.xorInto(0x5C, outerPadding)
+
+        function.reset()
+        function.update(innerPadding)
+
+        initialized = true
+    }
+
+    override fun update(byte: Byte) {
+        require(initialized)
+
+        function.update(byte)
+    }
+
+    override fun update(bytes: ByteArray) {
+        require(initialized)
+
+        function.update(bytes)
+    }
+
+    override fun digestInto(destination: ByteArray, destinationOffset: Int) {
+        require(initialized)
+
+        function.digestInto(inner)
+        function.update(outerPadding)
+        function.update(inner)
+        function.digestInto(destination, destinationOffset)
+
+        function.update(innerPadding)
     }
 
     private fun pad(key: ByteArray): ByteArray {
-        return ByteArray(function.block).also {
-            when {
-                key.size > function.block -> function.hashInto(key, it)
-                else -> key.copyInto(it)
-            }
+        val padded = ByteArray(function.block)
+        when {
+            key.size > function.block -> function.hashInto(key, padded)
+            else -> key.copyInto(padded)
         }
+        return padded
     }
 }
diff --git a/src/commonMain/kotlin/com/infendro/mac/MAC.kt b/src/commonMain/kotlin/com/infendro/mac/MAC.kt
index 7d90d41..289799a 100644
--- a/src/commonMain/kotlin/com/infendro/mac/MAC.kt
+++ b/src/commonMain/kotlin/com/infendro/mac/MAC.kt
@@ -1,15 +1,38 @@
 package com.infendro.mac
 
-interface MAC {
-    val bytes: Int
+abstract class MAC(
+    val bytes: Int,
+) {
     val bits: Int
         get() = bytes * 8
 
-    fun hashInto(key: ByteArray, value: ByteArray, destination: ByteArray, destinationOffset: Int = 0)
+    abstract fun reset()
+
+    abstract fun init(key: ByteArray)
+
+    abstract fun update(byte: Byte)
+    abstract fun update(bytes: ByteArray)
+
+    abstract fun digestInto(destination: ByteArray, destinationOffset: Int = 0)
+
+    fun digest(): ByteArray {
+        val result = ByteArray(bytes)
+        digestInto(result)
+        return result
+    }
+
+    fun hashInto(key: ByteArray, value: ByteArray, destination: ByteArray, destinationOffset: Int = 0) {
+        init(key)
+        update(value)
+        digestInto(destination, destinationOffset)
+        reset()
+    }
 
     fun hash(key: ByteArray, value: ByteArray): ByteArray {
-        val result = ByteArray(bytes)
-        hashInto(key, value, result)
+        init(key)
+        update(value)
+        val result = digest()
+        reset()
         return result
     }
 }
diff --git a/src/commonTest/kotlin/com/infendro/mac/HMAC.kt b/src/commonTest/kotlin/com/infendro/mac/HMAC.kt
index dec7dda..0c7edb7 100644
--- a/src/commonTest/kotlin/com/infendro/mac/HMAC.kt
+++ b/src/commonTest/kotlin/com/infendro/mac/HMAC.kt
@@ -6,7 +6,7 @@ import kotlin.test.assertContentEquals
 import kotlin.test.assertEquals
 
 class `HMAC Test` {
-    val hmac = HMAC(`SHA-256`)
+    val hmac = HMAC(`SHA-256`())
 
     @Test
     fun bytes() {