Add delegated xchacha20poly1305 decrypt

multiplatform-crypto-delegated/src/commonTest/kotlin/com/ionspin/kotlin/crypto/authenticated/XChaCha20Poly1305Test.kt

@@ -7,6 +7,7 @@ import com.ionspin.kotlin.crypto.util.hexColumsPrint
 import com.ionspin.kotlin.crypto.util.testBlocking
 import kotlin.test.Ignore
 import kotlin.test.Test
+import kotlin.test.assertFails
 import kotlin.test.assertTrue
 
 /**
@@ -210,12 +211,28 @@ class XChaCha20Poly1305Test {
             0xDEU, 0xFBU, 0x5CU, 0x7FU, 0x1CU, 0x26U, 0x32U, 0x2CU, 0x51U, 0xF6U, 0xEFU, 0xC6U, 0x34U, 0xC4U, 0xACU, 0x6CU,
             0xE8U, 0xF9U, 0x4BU, 0xABU, 0xA3U,
         )
-        val xcha = XChaCha20Poly1305Delegated(key, state, header)
+        val encryptor = XChaCha20Poly1305Delegated(key, state, header)
+        val decryptor = XChaCha20Poly1305Delegated(key, state, header)
         val data = UByteArray(100) { 0U }
-        val result = xcha.encrypt(data)
+        val result = encryptor.encrypt(data)
-
+        val decrypted = decryptor.decrypt(result)
+        println("Encrypted -----------")
+        result.hexColumsPrint()
+        println("Encrypted end -----------")
+        println("Decrypted -----------")
+        decrypted.hexColumsPrint()
+        println("Decrypted end -----------")
         assertTrue {
-            expected.contentEquals(result)
+            expected.contentEquals(result) && decrypted.contentEquals(data)
+        }
+        val messedUpTag = result.copyOf()
+        messedUpTag[messedUpTag.size - 2] = 0U
+        assertFails {
+            val decryptorForWrongTag = XChaCha20Poly1305Delegated(key, state, header)
+            val plaintext = decryptorForWrongTag.decrypt(messedUpTag)
+            println("Decrypted with wrong tag -----------")
+            plaintext.hexColumsPrint()
+            println("Decrypted with wrong tag end -----------")
         }
     }
 }

multiplatform-crypto-delegated/src/jsMain/kotlin/com/ionspin/kotlin/crypto/JsSodiumInterface.kt

@@ -50,6 +50,7 @@ interface JsSodiumInterface {
 
     //decrypt
     fun crypto_secretstream_xchacha20poly1305_init_pull(header: Uint8Array, key: Uint8Array) : dynamic
+    fun crypto_secretstream_xchacha20poly1305_pull(state: dynamic, ciphertext: Uint8Array, additionalData: Uint8Array) : dynamic
 
 
 }

multiplatform-crypto-delegated/src/jsMain/kotlin/com/ionspin/kotlin/crypto/authenticated/XChaCha20Poly1305Delegated.kt

@@ -1,6 +1,8 @@
 package com.ionspin.kotlin.crypto.authenticated
 
+import com.ionspin.kotlin.crypto.InvalidTagException
 import com.ionspin.kotlin.crypto.getSodium
+import com.ionspin.kotlin.crypto.util.hexColumsPrint
 import ext.libsodium.com.ionspin.kotlin.crypto.toUByteArray
 import ext.libsodium.com.ionspin.kotlin.crypto.toUInt8Array
 import org.khronos.webgl.Uint8Array
@@ -84,7 +86,15 @@ actual class XChaCha20Poly1305Delegated internal actual constructor() {
     }
 
     actual fun decrypt(data: UByteArray, additionalData: UByteArray): UByteArray {
-        TODO("not implemented yet")
+        val decryptedWithTag = getSodium().crypto_secretstream_xchacha20poly1305_pull(state, data.toUInt8Array(), additionalData.toUInt8Array())
+        val decrypted = decryptedWithTag.message as Uint8Array
+        val validTag = decryptedWithTag.tag as UInt
+
+        if (validTag != 0U) {
+            println("Tag validation failed")
+            throw InvalidTagException()
+        }
+        return decrypted.toUByteArray()
     }
 
 

multiplatform-crypto-delegated/src/jvmMain/kotlin/com/ionspin/kotlin/crypto/authenticated/XChaCha20Poly1305Delegated.kt

@@ -2,6 +2,7 @@ package com.ionspin.kotlin.crypto.authenticated
 
 import com.goterl.lazycode.lazysodium.SodiumJava
 import com.goterl.lazycode.lazysodium.interfaces.SecretStream
+import com.ionspin.kotlin.crypto.InvalidTagException
 import com.ionspin.kotlin.crypto.util.hexColumsPrint
 
 /**
@@ -89,14 +90,18 @@ actual class XChaCha20Poly1305Delegated internal actual constructor() {
     actual fun decrypt(data: UByteArray, additionalData: UByteArray): UByteArray {
         val plaintext = ByteArray(data.size - 17)
 
-        sodium.crypto_secretstream_xchacha20poly1305_pull(
+        val validTag = sodium.crypto_secretstream_xchacha20poly1305_pull(
             state, plaintext, null,
-            data.sliceArray(0 until 1).asByteArray(),
+            null,
-            data.sliceArray(1 until data.size).asByteArray(),
+            data.asByteArray(),
-            (data.size - 17).toLong(),
+            (data.size).toLong(),
             additionalData.asByteArray(),
             additionalData.size.toLong()
         )
+        if (validTag != 0) {
+            println("Tag validation failed")
+            throw InvalidTagException()
+        }
         return plaintext.asUByteArray()
 
     }

multiplatform-crypto-delegated/src/nativeMain/kotlin/com/ionspin/kotlin/crypto/authenticated/XChaCha20Poly1305Delegated.kt

@@ -1,6 +1,7 @@
 package com.ionspin.kotlin.crypto.authenticated
 
 import com.ionspin.kotlin.bignum.integer.util.hexColumsPrint
+import com.ionspin.kotlin.crypto.InvalidTagException
 import kotlinx.cinterop.*
 import libsodium.*
 import platform.posix.malloc
@@ -127,7 +128,24 @@ actual class XChaCha20Poly1305Delegated internal actual constructor() {
     }
 
     actual fun decrypt(data: UByteArray, additionalData: UByteArray): UByteArray {
-        TODO("not implemented yet")
+        val plaintext = UByteArray(data.size - crypto_secretstream_xchacha20poly1305_ABYTES.toInt())
+        val plaintextPinned = plaintext.pin()
+        val validTag = crypto_secretstream_xchacha20poly1305_pull(
+            state.ptr,
+            plaintextPinned.addressOf(0),
+            null,
+            null,
+            data.toCValues(),
+            data.size.convert(),
+            additionalData.toCValues(),
+            additionalData.size.convert()
+        )
+        plaintextPinned.unpin()
+        if (validTag != 0) {
+            println("Tag validation failed")
+            throw InvalidTagException()
+        }
+        return plaintext
     }