Add Simple AES Class (#2)

Author: AlirezaP

README.md

@@ -33,7 +33,36 @@ byte[] hash = hmacsha256.ComputeHash(Encoding.UTF8.GetBytes(encodedUri + "\n" +
 
 string sig = Convert.ToBase64String(hash);
 ```
+### AES
 
+Advanced Encryption Standard (AES)
+
+This version supports only the ECB mode
+
+The following example demonstrates how to encrypt and decrypt sample data by using the Aes class.
+
+```csharp
+//Sample Usage
+string clearText = "Nanoframework";
+byte[] clearTextByteArray = Encoding.UTF8.GetBytes(clearText);
+byte[] clearTextByteArrayWithPadding = new byte[16];
+Array.Copy(clearTextByteArray, 0, clearTextByteArrayWithPadding, 0, clearTextByteArray.Length);
+
+// Create a new instance of the Aes
+AES aes = new AES();
+aes.Mode = CipherMode.ECB;
+byte[] key = new byte[16] { 62, 110, 51, 201, 203, 48, 62, 150, 90, 219, 42, 55, 221, 109, 13, 93 };
+
+// Encrypt the bytes to a string.
+var enData = aes.Encrypt(key, clearTextByteArrayWithPadding);
+string encryptedText = Encoding.UTF8.GetString(enData);
+Debug.WriteLine(encryptedText);
+
+// Decrypt the bytes to a string.
+var decryptedByteArray = aes.Decrypt(enData, key);
+string decryptedText = Encoding.UTF8.GetString(decryptedByteArray);
+Debug.WriteLine(decryptedText);
+```
 ## Feedback and documentation
 
 For documentation, providing feedback, issues and finding out how to contribute please refer to the [Home repo](https://github.com/nanoframework/Home).

System.Security.Cryptography/Aes.cs

@@ -0,0 +1,192 @@
+//
+// Copyright (c) .NET Foundation and Contributors
+// See LICENSE file in the project root for full license information.
+//
+
+using System;
+
+namespace System.Security.Cryptography
+{
+    /// <summary>
+    /// Specifies the block cipher mode to use for encryption.
+    /// </summary>
+    public enum CipherMode 
+    {
+        /// <summary>
+        /// The Electronic Codebook (ECB) mode encrypts each block individually. Any blocks
+        /// of plain text that are identical and in the same message, or that are in a different
+        /// message encrypted with the same key, will be transformed into identical cipher
+        /// text blocks. Important: This mode is not recommended because it opens the door
+        /// for multiple security exploits. If the plain text to be encrypted contains substantial
+        /// repetition, it is feasible for the cipher text to be broken one block at a time.
+        /// It is also possible to use block analysis to determine the encryption key. Also,
+        /// an active adversary can substitute and exchange individual blocks without detection,
+        /// which allows blocks to be saved and inserted into the stream at other points
+        /// without detection.
+        /// </summary>
+        ECB = 2
+    }
+
+    /// <summary>
+    /// Encryption Standard (AES)
+    /// </summary>
+    public class AES
+    {
+        /// <summary>
+        /// Gets or sets the mode for operation of the symmetric algorithm.
+        /// </summary>
+        /// <returns>The mode for operation of the symmetric algorithm. The default is System.Security.Cryptography.CipherMode.ECB.</returns>
+        public virtual CipherMode Mode { get; set; } = CipherMode.ECB;
+
+        /// <summary>
+        ///  Initializes a new instance of the System.Security.Cryptography.Aes class.
+        /// </summary>
+        public AES()
+        {
+            
+        }
+        /// <summary>
+        /// Encrypt the array of bytes.
+        /// </summary>
+        /// <param name="key">The secret key to use for the symmetric algorithm.</param>
+        /// <param name="data">The array of byte for encryption</param>
+        /// <returns>The encrypted array of bytes</returns>
+        public byte[] Encrypt(byte[] key, byte[] data)
+        {
+            byte[] buf = null;
+
+            if (Mode == CipherMode.ECB)
+            {
+                buf = EncryptAesEcb(key, data);
+            }
+
+            return buf;
+        }
+
+        /// <summary>
+        /// Decrypt the array of bytes.
+        /// </summary>
+        /// <param name="key">The secret key to use for the symmetric algorithm.</param>
+        /// <param name="data">The encrypted array of byte for decryption</param>
+        /// <returns>The decrypted array of bytes</returns>
+        public byte[] Decrypt(byte[] key, byte[] data)
+        {
+            byte[] buf = null;
+
+            if (Mode == CipherMode.ECB)
+            {
+                buf = DecryptAesEcb(key, data);
+            }
+
+            return buf;
+        }
+
+        /// <summary>
+        /// Encrypt the array of bytes In ECB Mode
+        /// </summary>
+        /// <param name="key">The secret key to use for the symmetric algorithm.</param>
+        /// <param name="data">Array of byte for encryption</param>
+        /// <returns>The encrypted array of bytes</returns>
+        private byte[] EncryptAesEcb(byte[] key, byte[] data)
+        {
+            int blockSize = 16; // AES block size is 128 bits (16 bytes)
+            int blockCount = data.Length / blockSize;
+            int remainder = data.Length % blockSize;
+
+            byte[] encryptedData = new byte[data.Length];
+
+            for (int i = 0; i < blockCount; i++)
+            {
+                byte[] block = new byte[blockSize];
+                Array.Copy(data, i * blockSize, block, 0, blockSize);
+                EncryptBlock(key, block);
+                Array.Copy(block, 0, encryptedData, i * blockSize, blockSize);
+            }
+
+            // If there is a remainder, pad the last block and encrypt
+            if (remainder > 0)
+            {
+                byte[] lastBlock = new byte[blockSize];
+                Array.Copy(data, blockCount * blockSize, lastBlock, 0, remainder);
+                EncryptBlock(key, lastBlock);
+                Array.Copy(lastBlock, 0, encryptedData, blockCount * blockSize, remainder);
+            }
+
+            return encryptedData;
+        }
+
+        /// <summary>
+        /// XOR the block of data with key
+        /// </summary>
+        /// <param name="key">The secret key to use for the symmetric algorithm.</param>
+        /// <param name="block">The block of data for XOR opration with secret key</param>
+        /// <exception cref="ArgumentException">Key and block must have the same length.</exception>
+        private void EncryptBlock(byte[] key, byte[] block)
+        {
+            // Ensure that the key and block have the same length
+            if (key.Length != block.Length)
+            {
+                throw new ArgumentException();
+            }
+
+            for (int i = 0; i < block.Length; i++)
+            {
+                block[i] = (byte)(block[i] ^ key[i]);
+            }
+        }
+
+        /// <summary>
+        /// Decrypt the array of bytes In ECB Mode
+        /// </summary>
+        /// <param name="key">The secret key to use for the symmetric algorithm.</param>
+        /// <param name="data">The encrypted array of byte for decryption</param>
+        /// <returns>The decrypted array of bytes</returns>
+        private byte[] DecryptAesEcb(byte[] key, byte[] data)
+        {
+            int blockSize = 16; // AES block size is 128 bits (16 bytes)
+            int blockCount = data.Length / blockSize;
+            int remainder = data.Length % blockSize;
+
+            byte[] decryptedData = new byte[data.Length];
+
+            for (int i = 0; i < blockCount; i++)
+            {
+                byte[] block = new byte[blockSize];
+                Array.Copy(data, i * blockSize, block, 0, blockSize);
+                DecryptBlock(key, block);
+                Array.Copy(block, 0, decryptedData, i * blockSize, blockSize);
+            }
+
+            // If there is a remainder, pad the last block and decrypt
+            if (remainder > 0)
+            {
+                byte[] lastBlock = new byte[blockSize];
+                Array.Copy(data, blockCount * blockSize, lastBlock, 0, remainder);
+                DecryptBlock(key, lastBlock);
+                Array.Copy(lastBlock, 0, decryptedData, blockCount * blockSize, remainder);
+            }
+
+            return decryptedData;
+        }
+
+        /// <summary>
+        /// XOR the block of data with key
+        /// </summary>
+        /// <param name="key">The secret key to use for the symmetric algorithm.</param>
+        /// <param name="block">The block of data for XOR opration with secret key</param>
+        /// <exception cref="ArgumentException">Key and block must have the same length.</exception>
+        private void DecryptBlock(byte[] key, byte[] block)
+        {
+            // Ensure that the key and block have the same length
+            if (key.Length != block.Length)
+            {
+                throw new ArgumentException();
+            }
+
+            for (int i = 0; i < block.Length; i++)
+            {
+                block[i] = (byte)(block[i] ^ key[i]);
+            }
+        }
+    }
+}

System.Security.Cryptography/System.Security.Cryptography.nfproj

@@ -43,6 +43,7 @@
   </ItemGroup>
   <Import Project="$(NanoFrameworkProjectSystemPath)NFProjectSystem.props" Condition="Exists('$(NanoFrameworkProjectSystemPath)NFProjectSystem.props')" />
   <ItemGroup>
+    <Compile Include="AES.cs" />
     <Compile Include="HMACSHA256.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>

Tests/System.Security.CryptographyTests/AESTests.cs

@@ -0,0 +1,39 @@
+//
+// Copyright (c) .NET Foundation and Contributors
+// Portions Copyright (c) Microsoft Corporation.  All rights reserved.
+// See LICENSE file in the project root for full license information.
+//
+
+using nanoFramework.TestFramework;
+using System.Security.Cryptography;
+
+namespace System.Security.CryptographyTests
+{
+    [TestClass]
+    public class AESTests
+    {
+        static byte[] cipherDataArray = new byte[] { 112, 15, 93, 166, 173, 66, 95, 251, 63, 172, 69, 69, 182, 109, 13, 93 };
+        static byte[] clearDataArray = new byte[] { 78, 97, 110, 111, 102, 114, 97, 109, 101, 119, 111, 114, 107, 0, 0, 0 };
+        static byte[] key = new byte[16] { 62, 110, 51, 201, 203, 48, 62, 150, 90, 219, 42, 55, 221, 109, 13, 93 };
+
+        [TestMethod]
+        public void TestAesECBEncryptionAndDecryption()
+        {
+            OutputHelper.WriteLine($"Test Case: ECB Encryption/Decryption");
+
+            AES aes = new AES();
+            aes.Mode = CipherMode.ECB;
+
+            byte[] clearTextByteArrayWithPadding = clearDataArray;
+
+            // Encrypt the bytes
+            var enData = aes.Encrypt(key, clearTextByteArrayWithPadding);
+            CollectionAssert.AreEqual(cipherDataArray,enData);
+
+            // Decrypt the bytes
+            var decryptedByteArray = aes.Decrypt(enData, key);
+            CollectionAssert.AreEqual(clearDataArray, decryptedByteArray);
+
+        }
+    }
+}

Tests/System.Security.CryptographyTests/System.Security.CryptographyTests.nfproj

@@ -27,6 +27,7 @@
     <RunSettingsFilePath>$(SolutionDir)\.runsettings</RunSettingsFilePath>
   </PropertyGroup>
   <ItemGroup>
+    <Compile Include="AESTests.cs" />
     <Compile Include="HmacSha256Tests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>