Added decryption

README.md

@@ -17,7 +17,16 @@ After that tenative plan is to add 25519 curve based signing and key exchange ne
 
 ## Should I use this in production?
 
-No, it's untested and unproven. 
+No.
+
+## Should I use this in code that is critical in any way, shape or form?
+
+No.
+
+## Why?
+
+This is an experimental implementation, mostly for expanding personal understanding of cryptography. 
+It's not peer reviewed, not guaranteed to be bug free, and not guaranteed to be secure.
 
 ## Supported
 
@@ -26,6 +35,9 @@ No, it's untested and unproven.
 * SHA512
 * SHA256
 
+## Symmetric cipher 
+* AES
+
 More to come.
 
 ## Integration

multiplatform-crypto/src/commonMain/kotlin/com/ionspin/kotlin/crypto/symmetric/Aes.kt

@@ -4,9 +4,9 @@ package com.ionspin.kotlin.crypto.symmetric
  * Created by Ugljesa Jovanovic (jovanovic.ugljesa@gmail.com) on 07/Sep/2019
  */
 @ExperimentalUnsignedTypes
-class Aes(val aesKey: AesKey, val input: Array<UByte>) {
+internal class Aes internal constructor(val aesKey: AesKey, val input: Array<UByte>) {
     companion object {
-        val sBox: UByteArray =
+        private val sBox: UByteArray =
             ubyteArrayOf(
                 // @formatter:off
                 0x63U, 0x7cU, 0x77U, 0x7bU, 0xf2U, 0x6bU, 0x6fU, 0xc5U, 0x30U, 0x01U, 0x67U, 0x2bU, 0xfeU, 0xd7U, 0xabU, 0x76U,
@@ -28,7 +28,7 @@ class Aes(val aesKey: AesKey, val input: Array<UByte>) {
                     // @formatter:on
             )
 
-        val inverseSBox: UByteArray =
+        private val inverseSBox: UByteArray =
             ubyteArrayOf(
                 // @formatter:off
                 0x52U, 0x09U, 0x6aU, 0xd5U, 0x30U, 0x36U, 0xa5U, 0x38U, 0xbfU, 0x40U, 0xa3U, 0x9eU, 0x81U, 0xf3U, 0xd7U, 0xfbU,
@@ -52,6 +52,14 @@ class Aes(val aesKey: AesKey, val input: Array<UByte>) {
 
         val rcon: UByteArray = ubyteArrayOf(0x8DU, 0x01U, 0x02U, 0x04U, 0x08U, 0x10U, 0x20U, 0x40U, 0x80U, 0x1BU, 0x36U)
 
+        fun encrypt(aesKey: AesKey, input: Array<UByte>): Array<UByte> {
+            return Aes(aesKey, input).encrypt()
+        }
+
+        fun decrypt(aesKey: AesKey, input: Array<UByte>): Array<UByte> {
+            return Aes(aesKey, input).decrypt()
+        }
+
     }
 
     init {
@@ -60,11 +68,11 @@ class Aes(val aesKey: AesKey, val input: Array<UByte>) {
         }
     }
 
-    val state: Array<Array<UByte>> = (0 until 4).map{ outerCounter ->
+    val state: Array<Array<UByte>> = (0 until 4).map { outerCounter ->
         Array<UByte>(4) { innerCounter -> input[innerCounter * 4 + outerCounter] }
     }.toTypedArray()
 
-    val numberOfRounds = when(aesKey) {
+    val numberOfRounds = when (aesKey) {
         is AesKey.Aes128Key -> 10
         is AesKey.Aes192Key -> 12
         is AesKey.Aes256Key -> 14
@@ -73,7 +81,6 @@ class Aes(val aesKey: AesKey, val input: Array<UByte>) {
     val expandedKey: Array<Array<UByte>> = expandKey()
 
 
-
     var round = 0
 
 
@@ -91,6 +98,20 @@ class Aes(val aesKey: AesKey, val input: Array<UByte>) {
         return sBox[firstDigit * 16 + secondDigit]
     }
 
+    fun inverseSubBytes() {
+        state.forEachIndexed { indexRow, row ->
+            row.forEachIndexed { indexColumn, element ->
+                state[indexRow][indexColumn] = getInverseSBoxValue(element)
+            }
+        }
+    }
+
+    fun getInverseSBoxValue(element: UByte): UByte {
+        val firstDigit = (element / 16U).toInt()
+        val secondDigit = (element % 16U).toInt()
+        return inverseSBox[firstDigit * 16 + secondDigit]
+    }
+
     fun shiftRows() {
         state[0] = arrayOf(state[0][0], state[0][1], state[0][2], state[0][3])
         state[1] = arrayOf(state[1][1], state[1][2], state[1][3], state[1][0])
@@ -98,22 +119,40 @@ class Aes(val aesKey: AesKey, val input: Array<UByte>) {
         state[3] = arrayOf(state[3][3], state[3][0], state[3][1], state[3][2])
     }
 
+    fun inversShiftRows() {
+        state[0] = arrayOf(state[0][0], state[0][1], state[0][2], state[0][3])
+        state[1] = arrayOf(state[1][3], state[1][0], state[1][1], state[1][2])
+        state[2] = arrayOf(state[2][2], state[2][3], state[2][0], state[2][1])
+        state[3] = arrayOf(state[3][1], state[3][2], state[3][3], state[3][0])
+    }
+
     fun mixColumns() {
         val stateMixed: Array<Array<UByte>> = (0 until 4).map {
             Array<UByte>(4) { 0U }
         }.toTypedArray()
         for (c in 0..3) {
 
-            stateMixed[0][c] = (2U gfm state[0][c]) xor galoisFieldMultiply(
+            stateMixed[0][c] = (2U gfm state[0][c]) xor (3U gfm state[1][c]) xor state[2][c] xor state[3][c]
-                3U,
+            stateMixed[1][c] = state[0][c] xor (2U gfm state[1][c]) xor (3U gfm state[2][c]) xor state[3][c]
-                state[1][c]
+            stateMixed[2][c] = state[0][c] xor state[1][c] xor (2U gfm state[2][c]) xor (3U gfm state[3][c])
-            ) xor state[2][c] xor state[3][c]
+            stateMixed[3][c] = 3U gfm state[0][c] xor state[1][c] xor state[2][c] xor (2U gfm state[3][c])
+        }
+        stateMixed.copyInto(state)
+    }
+
+    fun inverseMixColumns() {
+        val stateMixed: Array<Array<UByte>> = (0 until 4).map {
+            Array<UByte>(4) { 0U }
+        }.toTypedArray()
+        for (c in 0..3) {
+            stateMixed[0][c] =
+                (0x0eU gfm state[0][c]) xor (0x0bU gfm state[1][c]) xor (0x0dU gfm state[2][c]) xor (0x09U gfm state[3][c])
             stateMixed[1][c] =
-                state[0][c] xor (2U gfm state[1][c]) xor (3U gfm state[2][c]) xor state[3][c]
+                (0x09U gfm state[0][c]) xor (0x0eU gfm state[1][c]) xor (0x0bU gfm state[2][c]) xor (0x0dU gfm state[3][c])
             stateMixed[2][c] =
-                state[0][c] xor state[1][c] xor (2U gfm state[2][c]) xor (3U gfm state[3][c])
+                (0x0dU gfm state[0][c]) xor (0x09U gfm state[1][c]) xor (0x0eU gfm state[2][c]) xor (0x0bU gfm state[3][c])
             stateMixed[3][c] =
-                3U gfm state[0][c] xor state[1][c] xor state[2][c] xor (2U gfm state[3][c])
+                (0x0bU gfm state[0][c]) xor (0x0dU gfm state[1][c]) xor (0x09U gfm state[2][c]) xor (0x0eU gfm state[3][c])
         }
         stateMixed.copyInto(state)
     }
@@ -153,6 +192,16 @@ class Aes(val aesKey: AesKey, val input: Array<UByte>) {
         round++
     }
 
+    fun inverseAddRoundKey() {
+        for (i in 0 until 4) {
+            state[0][i] = state[0][i] xor expandedKey[round * 4 + i][0]
+            state[1][i] = state[1][i] xor expandedKey[round * 4 + i][1]
+            state[2][i] = state[2][i] xor expandedKey[round * 4 + i][2]
+            state[3][i] = state[3][i] xor expandedKey[round * 4 + i][3]
+        }
+        round--
+    }
+
     infix fun UInt.gfm(second: UByte): UByte {
         return galoisFieldMultiply(this.toUByte(), second)
     }
@@ -200,24 +249,72 @@ class Aes(val aesKey: AesKey, val input: Array<UByte>) {
         return expandedKey
     }
 
-    fun encrypt() : Array<UByte> {
+    fun encrypt(): Array<UByte> {
+        printState()
         addRoundKey()
-
+        printState()
         for (i in 0 until numberOfRounds - 1) {
             subBytes()
+            printState()
             shiftRows()
+            printState()
             mixColumns()
+            printState()
             addRoundKey()
+            printState()
         }
 
         subBytes()
+        printState()
         shiftRows()
+        printState()
         addRoundKey()
-        return state.flatten().toTypedArray()
+        printState()
+        val transposedMatrix = (0 until 4).map { outerCounter ->
+            Array<UByte>(4) { 0U }
+        }.toTypedArray()
+        for (i in 0 until 4) {
+            for (j in 0 until 4) {
+                transposedMatrix[i][j] = state[j][i]
+            }
+        }
+//        printState(transposedMatrix)
+        return transposedMatrix.flatten().toTypedArray()
     }
 
-    fun decrypt() : Array<UByte> {
+    fun decrypt(): Array<UByte> {
-        return ubyteArrayOf().toTypedArray()
+        round = numberOfRounds
+        printState()
+        inverseAddRoundKey()
+        printState()
+        for (i in 0 until numberOfRounds - 1) {
+            inversShiftRows()
+            printState()
+            inverseSubBytes()
+            printState()
+            inverseAddRoundKey()
+            printState()
+            inverseMixColumns()
+            printState()
+        }
+
+        inversShiftRows()
+        printState()
+        inverseSubBytes()
+        printState()
+        inverseAddRoundKey()
+        printState()
+
+        val transposedMatrix =  (0 until 4).map { outerCounter ->
+            Array<UByte>(4) { 0U }
+        }.toTypedArray()
+        for (i in 0 until 4) {
+            for (j in 0 until 4) {
+                transposedMatrix[i][j] = state[j][i]
+            }
+        }
+        printState(transposedMatrix)
+        return transposedMatrix.flatten().toTypedArray()
     }
 
     fun printState() {
@@ -227,6 +324,13 @@ class Aes(val aesKey: AesKey, val input: Array<UByte>) {
         }
     }
 
+    fun printState(specific : Array<Array<UByte>>) {
+        println()
+        specific.forEach {
+            println(it.joinToString(separator = " ") { it.toString(16) })
+        }
+    }
+
 
 }
 

multiplatform-crypto/src/commonTest/kotlin/com/ionspin/kotlin/crypto/symmetric/AesTest.kt

@@ -23,9 +23,6 @@ class AesTest {
         val aes = Aes(AesKey.Aes128Key(irrelevantKey), irrelevantInput)
         fakeState.copyInto(aes.state)
         aes.subBytes()
-        aes.state.forEach {
-            println(it.joinToString { it.toString(16) })
-        }
         assertTrue {
             aes.state[0][0] == 0xEDU.toUByte()
         }
@@ -48,9 +45,6 @@ class AesTest {
         val aes = Aes(AesKey.Aes128Key(irrelevantKey), irrelevantInput)
         fakeState.copyInto(aes.state)
         aes.shiftRows()
-        aes.state.forEach {
-            println(it.joinToString { it.toString(16) })
-        }
         assertTrue {
             aes.state.contentDeepEquals(expectedState)
         }
@@ -98,9 +92,6 @@ class AesTest {
         val aes = Aes(AesKey.Aes128Key(irrelevantKey), irrelevantInput)
         fakeState.copyInto(aes.state)
         aes.mixColumns()
-        aes.state.forEach {
-            println(it.joinToString { it.toString(16) })
-        }
         assertTrue {
             aes.state.contentDeepEquals(expectedState)
         }
@@ -190,7 +181,7 @@ class AesTest {
     fun testEncryption() {
         val input = "3243f6a8885a308d313198a2e0370734"
         val key = "2b7e151628aed2a6abf7158809cf4f3c"
-        val expectedResult = "3902dc1925dc116a8409850b1dfb9732"
+        val expectedResult = "3925841d02dc09fbdc118597196a0b32"
 
         val aes = Aes(AesKey.Aes128Key(key), input.chunked(2).map { it.toInt(16).toUByte() }.toTypedArray())
         val result = aes.encrypt()
@@ -198,4 +189,44 @@ class AesTest {
             result.contentEquals(expectedResult.chunked(2).map { it.toInt(16).toUByte() }.toTypedArray())
         }
     }
+
+    @Test
+    fun testDecryption() {
+        val input = "3243f6a8885a308d313198a2e0370734"
+        val key = "2b7e151628aed2a6abf7158809cf4f3c"
+        val expectedResult = "3925841d02dc09fbdc118597196a0b32"
+        val original = input.chunked(2).map { it.toInt(16).toUByte() }.toTypedArray()
+        val aes = Aes(AesKey.Aes128Key(key), original)
+        val encrypted = aes.encrypt()
+        assertTrue {
+            encrypted.contentEquals(expectedResult.chunked(2).map { it.toInt(16).toUByte() }.toTypedArray())
+        }
+        val decrypted = Aes.decrypt(AesKey.Aes128Key(key), encrypted)
+        assertTrue {
+            decrypted.contentEquals(original)
+        }
+    }
+
+    @Test
+    fun testDecryption2() {
+        val input = "00112233445566778899aabbccddeeff"
+        val key = "000102030405060708090a0b0c0d0e0f"
+        val expectedResult = "69c4e0d86a7b0430d8cdb78070b4c55a"
+        val original = input.chunked(2).map { it.toInt(16).toUByte() }.toTypedArray()
+        val aes = Aes(AesKey.Aes128Key(key), original)
+        val encrypted = aes.encrypt()
+        assertTrue {
+            encrypted.contentEquals(expectedResult.chunked(2).map { it.toInt(16).toUByte() }.toTypedArray())
+        }
+        val aesDec = Aes(AesKey.Aes128Key(key), encrypted)
+        val decrypted = aesDec.decrypt()
+        assertTrue {
+            aesDec.expandedKey.contentDeepEquals(aes.expandedKey)
+        }
+        assertTrue {
+            decrypted.contentDeepEquals(original)
+        }
+    }
+
+
 }