README.md

@@ -15,7 +15,7 @@ repositories {
 }
 
 dependencies {
-    implementation("com.infendro:mac:1.4.0")
+    implementation("com.infendro:mac:1.5.0")
 }
 ```
 
@@ -24,7 +24,7 @@ dependencies {
 ```kotlin
 fun main() {
     // create an HMAC instance using SHA1
-    val hmac = HMAC(SHA1)
+    val hmac = HMAC(SHA1())
 
     // generate MAC
     val key = "secret".encodeToByteArray()

build.gradle.kts

@@ -5,7 +5,7 @@ import com.infendro.plugin.token
 import org.jetbrains.kotlin.gradle.ExperimentalWasmDsl
 
 group = "com.infendro"
-version = "1.4.0"
+version = "1.5.0"
 
 plugins {
     alias(libs.plugins.infendro)

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" }

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)
+    override fun reset() {
+        function.reset()
+        initialized = false
+        innerPadding.fill(0x00)
+        outerPadding.fill(0x00)
     }
-        val outer = ByteArray(function.block + function.bytes).also {
-            paddedKey.xorInto(0x5C, it)
-            function.hashInto(inner, it, function.block)
+
+    override fun init(key: ByteArray) {
+        val padded = pad(key)
+        padded.xorInto(0x36, innerPadding)
+        padded.xorInto(0x5C, outerPadding)
+
+        function.reset()
+        function.update(innerPadding)
+
+        initialized = true
     }
-        function.hashInto(outer, destination, destinationOffset)
+
+    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 {
+        val padded = ByteArray(function.block)
         when {
-                key.size > function.block -> function.hashInto(key, it)
-                else -> key.copyInto(it)
-            }
+            key.size > function.block -> function.hashInto(key, padded)
+            else -> key.copyInto(padded)
         }
+        return padded
     }
 }

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
     }
 }

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() {