diff --git a/buildSrc/src/main/kotlin/Deps.kt b/buildSrc/src/main/kotlin/Deps.kt
index 42e6ed7..1104855 100644
--- a/buildSrc/src/main/kotlin/Deps.kt
+++ b/buildSrc/src/main/kotlin/Deps.kt
@@ -16,16 +16,16 @@
 
 object Versions {
     val klock = "1.1.1"
-    val kotlinCoroutines = "1.3.0-M2"
+    val kotlinCoroutines = "1.3.0"
     val timber = "5.0.0-SNAPSHOT"
     val oshi = "3.12.0"
-    val kotlin = "1.3.40"
+    val kotlin = "1.3.50"
     val ktor = "1.1.1"
     val kotlinSerialization = "0.11.1"
     val nodePlugin = "1.3.0"
     val dokkaPlugin = "0.9.18"
 
-    val kotlinBigNumVersion = "0.1.0-SNAPSHOT"
+    val kotlinBigNumVersion = "0.1.1-SNAPSHOT"
 
 
 }
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index d83a619..4e8cbd5 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -16,6 +16,6 @@
 
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-5.1.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.1-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/multiplatform-crypto/src/commonMain/kotlin/com/ionspin/kotlin/crypto/symmetric/Aes.kt b/multiplatform-crypto/src/commonMain/kotlin/com/ionspin/kotlin/crypto/symmetric/Aes.kt
new file mode 100644
index 0000000..c11ff7a
--- /dev/null
+++ b/multiplatform-crypto/src/commonMain/kotlin/com/ionspin/kotlin/crypto/symmetric/Aes.kt
@@ -0,0 +1,66 @@
+package com.ionspin.kotlin.crypto.symmetric
+
+/**
+ * Created by Ugljesa Jovanovic (jovanovic.ugljesa@gmail.com) on 07/Sep/2019
+ */
+@ExperimentalUnsignedTypes
+class Aes {
+    companion object {
+        val sBox : UByteArray =
+                ubyteArrayOf(
+                        0x63U, 0x7cU, 0x77U, 0x7bU, 0xf2U, 0x6bU, 0x6fU, 0xc5U, 0x30U, 0x01U, 0x67U, 0x2bU, 0xfeU, 0xd7U, 0xabU, 0x76U,
+                        0xcaU, 0x82U, 0xc9U, 0x7dU, 0xfaU, 0x59U, 0x47U, 0xf0U, 0xadU, 0xd4U, 0xa2U, 0xafU, 0x9cU, 0xa4U, 0x72U, 0xc0U,
+                        0xb7U, 0xfdU, 0x93U, 0x26U, 0x36U, 0x3fU, 0xf7U, 0xccU, 0x34U, 0xa5U, 0xe5U, 0xf1U, 0x71U, 0xd8U, 0x31U, 0x15U,
+                        0x04U, 0xc7U, 0x23U, 0xc3U, 0x18U, 0x96U, 0x05U, 0x9aU, 0x07U, 0x12U, 0x80U, 0xe2U, 0xebU, 0x27U, 0xb2U, 0x75U,
+                        0x09U, 0x83U, 0x2cU, 0x1aU, 0x1bU, 0x6eU, 0x5aU, 0xa0U, 0x52U, 0x3bU, 0xd6U, 0xb3U, 0x29U, 0xe3U, 0x2fU, 0x84U,
+                        0x53U, 0xd1U, 0x00U, 0xedU, 0x20U, 0xfcU, 0xb1U, 0x5bU, 0x6aU, 0xcbU, 0xbeU, 0x39U, 0x4aU, 0x4cU, 0x58U, 0xcfU,
+                        0xd0U, 0xefU, 0xaaU, 0xfbU, 0x43U, 0x4dU, 0x33U, 0x85U, 0x45U, 0xf9U, 0x02U, 0x7fU, 0x50U, 0x3cU, 0x9fU, 0xa8U,
+                        0x51U, 0xa3U, 0x40U, 0x8fU, 0x92U, 0x9dU, 0x38U, 0xf5U, 0xbcU, 0xb6U, 0xdaU, 0x21U, 0x10U, 0xffU, 0xf3U, 0xd2U,
+                        0xcdU, 0x0cU, 0x13U, 0xecU, 0x5fU, 0x97U, 0x44U, 0x17U, 0xc4U, 0xa7U, 0x7eU, 0x3dU, 0x64U, 0x5dU, 0x19U, 0x73U,
+                        0x60U, 0x81U, 0x4fU, 0xdcU, 0x22U, 0x2aU, 0x90U, 0x88U, 0x46U, 0xeeU, 0xb8U, 0x14U, 0xdeU, 0x5eU, 0x0bU, 0xdbU,
+                        0xe0U, 0x32U, 0x3aU, 0x0aU, 0x49U, 0x06U, 0x24U, 0x5cU, 0xc2U, 0xd3U, 0xacU, 0x62U, 0x91U, 0x95U, 0xe4U, 0x79U,
+                        0xe7U, 0xc8U, 0x37U, 0x6dU, 0x8dU, 0xd5U, 0x4eU, 0xa9U, 0x6cU, 0x56U, 0xf4U, 0xeaU, 0x65U, 0x7aU, 0xaeU, 0x08U,
+                        0xbaU, 0x78U, 0x25U, 0x2eU, 0x1cU, 0xa6U, 0xb4U, 0xc6U, 0xe8U, 0xddU, 0x74U, 0x1fU, 0x4bU, 0xbdU, 0x8bU, 0x8aU,
+                        0x70U, 0x3eU, 0xb5U, 0x66U, 0x48U, 0x03U, 0xf6U, 0x0eU, 0x61U, 0x35U, 0x57U, 0xb9U, 0x86U, 0xc1U, 0x1dU, 0x9eU,
+                        0xe1U, 0xf8U, 0x98U, 0x11U, 0x69U, 0xd9U, 0x8eU, 0x94U, 0x9bU, 0x1eU, 0x87U, 0xe9U, 0xceU, 0x55U, 0x28U, 0xdfU,
+                        0x8cU, 0xa1U, 0x89U, 0x0dU, 0xbfU, 0xe6U, 0x42U, 0x68U, 0x41U, 0x99U, 0x2dU, 0x0fU, 0xb0U, 0x54U, 0xbbU, 0x16U
+                )
+    }
+
+    sealed class AesKey(val key: String, val keyLength: Int) {
+        class Aes128Key(key: String) : AesKey(key, 128)
+        class Aes192Key(key: String) : AesKey(key, 192)
+        class Aes256Key(key: String) : AesKey(key, 256)
+
+        init {
+            checkKeyLength(key, keyLength)
+        }
+
+        fun checkKeyLength(key: String, expectedLength: Int) {
+            if ((key.length / 2) != expectedLength) {
+                throw RuntimeException("Invalid key length")
+            }
+        }
+    }
+
+    val state : UByteArray = UByteArray(16) { 0U }
+
+    val stateMatrix : Array<Array<UByte>> = (0 until 4).map {
+        Array<UByte>(4) { 0U }
+    }.toTypedArray()
+
+    fun subBytes() {
+        stateMatrix.forEachIndexed { indexRow, row ->
+            row.forEachIndexed { indexColumn, element ->
+                val firstDigit = (element / 16U).toInt()
+                val secondDigit = (element % 16U).toInt()
+                val substitutionValue = sBox[firstDigit * 16 + secondDigit]
+                stateMatrix[indexRow][indexColumn] = substitutionValue
+            }
+        }
+    }
+
+    fun expandKey(key: AesKey) {
+
+    }
+}
diff --git a/multiplatform-crypto/src/commonTest/kotlin/com/ionspin/kotlin/crypto/symmetric/AesTest.kt b/multiplatform-crypto/src/commonTest/kotlin/com/ionspin/kotlin/crypto/symmetric/AesTest.kt
new file mode 100644
index 0000000..8e6a06c
--- /dev/null
+++ b/multiplatform-crypto/src/commonTest/kotlin/com/ionspin/kotlin/crypto/symmetric/AesTest.kt
@@ -0,0 +1,30 @@
+package com.ionspin.kotlin.crypto.symmetric
+
+import kotlin.test.Test
+import kotlin.test.assertTrue
+
+/**
+ * Created by Ugljesa Jovanovic (jovanovic.ugljesa@gmail.com) on 10/Sep/2019
+ */
+@ExperimentalUnsignedTypes
+class AesTest {
+
+    @Test
+    fun testSubBytes() {
+        val fakeState = arrayOf(
+                ubyteArrayOf(0x53U, 0U, 0U, 0U).toTypedArray(),
+                ubyteArrayOf(0U, 0U, 0U, 0U).toTypedArray(),
+                ubyteArrayOf(0U, 0U, 0U, 0U).toTypedArray(),
+                ubyteArrayOf(0U, 0U, 0U, 0U).toTypedArray()
+                )
+        val aes = Aes()
+        fakeState.copyInto(aes.stateMatrix)
+        aes.subBytes()
+        aes.stateMatrix.forEach{
+            println(it.joinToString { it.toString(16) })
+        }
+        assertTrue {
+            aes.stateMatrix[0][0] == 0xEDU.toUByte()
+        }
+    }
+}
\ No newline at end of file