From bbeaa837a995176ee845f990b19e0c8bd25da917 Mon Sep 17 00:00:00 2001
From: Kevin Froman <beardog@mailbox.org>
Date: Sat, 9 May 2020 05:26:38 -0500
Subject: [PATCH] finished standard authenticated pubkey encryption, but no
 decryption yet

---
 tests/Curve25519Test.cs                   | 52 +++++++++++++++++++++++
 tests/KeyGenTest.cs                       |  1 +
 treasurechest/chestcrypto/bytecombiner.cs | 13 ++++++
 treasurechest/chestcrypto/curve25519.cs   | 19 +++++++++
 treasurechest/chestcrypto/keygen.cs       |  9 +---
 5 files changed, 86 insertions(+), 8 deletions(-)
 create mode 100644 tests/Curve25519Test.cs
 create mode 100644 treasurechest/chestcrypto/bytecombiner.cs
 create mode 100644 treasurechest/chestcrypto/curve25519.cs

diff --git a/tests/Curve25519Test.cs b/tests/Curve25519Test.cs
new file mode 100644
index 0000000..8c1cc09
--- /dev/null
+++ b/tests/Curve25519Test.cs
@@ -0,0 +1,52 @@
+using NUnit.Framework;
+using chestcrypto;
+using System;
+using System.Text;
+using Sodium;
+
+namespace Curve25519Tests
+{
+    public class Tests
+    {
+        [SetUp]
+        public void Setup()
+        {
+        }
+
+        [Test]
+        public void TestCurve25519Encrypt()
+        {
+            var alice = PublicKeyBox.GenerateKeyPair();
+            var bob = PublicKeyBox.GenerateKeyPair();
+            string message = "Hello World";
+            byte[] message_bytes = UTF8Encoding.UTF8.GetBytes(message);
+            byte[] encrypted_with_nonce = chestcrypto.Curve25519.encrypt(alice.PrivateKey, bob.PublicKey, message_bytes);
+            byte[] used_nonce = new byte[24];
+
+            byte[] encrypted_without_nonce = new byte[encrypted_with_nonce.Length - 24];
+
+            int counter = 0;
+            Console.WriteLine(encrypted_without_nonce.Length);
+            for (int i = 24; i < encrypted_with_nonce.Length; i++){
+                //Console.WriteLine(counter);
+                encrypted_without_nonce[counter] = encrypted_with_nonce[i];
+                counter += 1;
+            }
+
+            for (int i = 0; i < chestcrypto.Curve25519.NONCE_BYTE_AMOUNT; i++){
+                //Console.WriteLine(i);
+                used_nonce[i] = encrypted_with_nonce[i];
+            }
+            for (int i = 0; i < chestcrypto.Curve25519.NONCE_BYTE_AMOUNT; i++){
+                if (used_nonce[i] != encrypted_with_nonce[i]){
+                    Assert.Fail();
+                }
+            }
+            byte[] decrypted = PublicKeyBox.Open(encrypted_without_nonce, used_nonce, bob.PrivateKey, alice.PublicKey);
+            if (!Encoding.UTF8.GetString(decrypted, 0, decrypted.Length).Equals(message)){
+                Console.WriteLine(Encoding.UTF8.GetString(decrypted, 0, decrypted.Length));
+                Assert.Fail();
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/tests/KeyGenTest.cs b/tests/KeyGenTest.cs
index f3ededf..1be3b17 100644
--- a/tests/KeyGenTest.cs
+++ b/tests/KeyGenTest.cs
@@ -23,5 +23,6 @@ namespace tests
             }
             Assert.Pass();
         }
+
     }
 }
\ No newline at end of file
diff --git a/treasurechest/chestcrypto/bytecombiner.cs b/treasurechest/chestcrypto/bytecombiner.cs
new file mode 100644
index 0000000..94f23cc
--- /dev/null
+++ b/treasurechest/chestcrypto/bytecombiner.cs
@@ -0,0 +1,13 @@
+using System;
+
+namespace chestcrypto{
+    internal class ByteCombiner{
+        internal static byte[] Combine(byte[] first, byte[] second)
+        {
+            byte[] bytes = new byte[first.Length + second.Length];
+            Buffer.BlockCopy(first, 0, bytes, 0, first.Length);
+            Buffer.BlockCopy(second, 0, bytes, first.Length, second.Length);
+            return bytes;
+        }
+    }
+}
\ No newline at end of file
diff --git a/treasurechest/chestcrypto/curve25519.cs b/treasurechest/chestcrypto/curve25519.cs
new file mode 100644
index 0000000..83637a9
--- /dev/null
+++ b/treasurechest/chestcrypto/curve25519.cs
@@ -0,0 +1,19 @@
+using Sodium;
+
+namespace chestcrypto {
+    public class Curve25519{
+
+        public static int NONCE_BYTE_AMOUNT = 24;
+        public static byte[] encrypt(byte[] privkey, byte[] pubkey, byte[] message){
+            byte[] nonce = Sodium.PublicKeyBox.GenerateNonce();
+            return ByteCombiner.Combine
+                    (nonce,
+                    Sodium.PublicKeyBox.Create(
+                        message,
+                        nonce,
+                        privkey,
+                        pubkey
+                    ));
+        }
+    }
+}
\ No newline at end of file
diff --git a/treasurechest/chestcrypto/keygen.cs b/treasurechest/chestcrypto/keygen.cs
index ff853b0..5c644dc 100644
--- a/treasurechest/chestcrypto/keygen.cs
+++ b/treasurechest/chestcrypto/keygen.cs
@@ -21,18 +21,11 @@ internal class Curve25519KeyGenerator{
 
 namespace chestcrypto{
     public class PrivateKeyGenerator{
-        private static byte[] Combine(byte[] first, byte[] second)
-        {
-            byte[] bytes = new byte[first.Length + second.Length];
-            Buffer.BlockCopy(first, 0, bytes, 0, first.Length);
-            Buffer.BlockCopy(second, 0, bytes, first.Length, second.Length);
-            return bytes;
-        }
         public static byte[] generate()
         {
             byte[] ed25519 = Ed25519KeyGenerator.generator();
             byte[] curve25519 = Curve25519KeyGenerator.generator();
-            byte[] key = Combine(ed25519, curve25519);
+            byte[] key = chestcrypto.ByteCombiner.Combine(ed25519, curve25519);
             Array.Clear(ed25519, 0, ed25519.Length);
             Array.Clear(curve25519, 0, curve25519.Length);
             return key;