Enabled selection of cipher mode (defaults to CBC), added method to conveniently create AES SymmetricCryptoStream.

These classes allow for convenient encryption with AES.

Proculite.Common.Test/Security/Cryptography/SymmetricCryptoStreamTest.cs

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+namespace Proculite.Common.Test.Security.Cryptography
+{
+    using System.Security.Cryptography;
+    using Proculite.Common.Security.Cryptography;
+
+    public class SymmetricCryptoStreamTest
+    {
+        [Fact]
+        public void InputEncryptedDecrypted_EqualOutput()
+        {
+            Aes aes = SimpleAes.Create(
+                [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+                [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
+            );
+
+            byte[] original = [1];
+            SymmetricCryptoStream symmetricCryptoStream = new SymmetricCryptoStream(aes);
+
+            byte[] result = symmetricCryptoStream.DecryptBytes(
+                symmetricCryptoStream.EncryptBytes(original)
+            );
+            Assert.Equal(result[0], original[0]);
+            Assert.Single(result);
+        }
+    }
+}

Proculite.Common/Security/Cryptography/SimpleAes.cs

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+using System.Security.Cryptography;
+
+namespace Proculite.Common.Security.Cryptography
+{
+    public static class SimpleAes
+    {
+        public static Aes Create(byte[] key, byte[] iv, CipherMode cipherMode = CipherMode.CBC)
+        {
+            Aes aes = Aes.Create();
+            aes.IV = iv;
+            aes.Key = key;
+            aes.Mode = cipherMode;
+
+            return aes;
+        }
+
+        public static SymmetricCryptoStream CreateCryptoStream(
+            byte[] key,
+            byte[] iv,
+            CipherMode cipherMode = CipherMode.CBC
+        )
+        {
+            Aes aes = Create(key, iv, cipherMode);
+            return new SymmetricCryptoStream(aes);
+        }
+    }
+}

Proculite.Common/Security/Cryptography/SymmetricCryptoStream.cs

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+using System.IO;
+using System.Security.Cryptography;
+
+namespace Proculite.Common.Security.Cryptography
+{
+    public class SymmetricCryptoStream
+    {
+        private readonly SymmetricAlgorithm _symmetricAlgorithm;
+
+        public SymmetricCryptoStream(SymmetricAlgorithm symmetricAlgorithm)
+        {
+            _symmetricAlgorithm = symmetricAlgorithm;
+        }
+
+        public void EncryptStream(Stream readFromStream, Stream writeToStream)
+        {
+            ICryptoTransform encryptor = _symmetricAlgorithm.CreateEncryptor();
+            using (
+                CryptoStream cryptoStream = new CryptoStream(
+                    readFromStream,
+                    encryptor,
+                    CryptoStreamMode.Read
+                )
+            )
+            {
+                cryptoStream.CopyTo(writeToStream);
+            }
+        }
+
+        public void DecryptStream(Stream readFromStream, Stream writeToStream)
+        {
+            ICryptoTransform decryptor = _symmetricAlgorithm.CreateDecryptor();
+            using (
+                CryptoStream cryptoStream = new CryptoStream(
+                    readFromStream,
+                    decryptor,
+                    CryptoStreamMode.Read
+                )
+            )
+            {
+                cryptoStream.CopyTo(writeToStream);
+            }
+        }
+
+        public byte[] EncryptBytes(byte[] source)
+        {
+            MemoryStream sourceBytes = new MemoryStream(source);
+            MemoryStream encryptedBytes = new MemoryStream();
+            EncryptStream(sourceBytes, encryptedBytes);
+
+            return encryptedBytes.ToArray();
+        }
+
+        public byte[] DecryptBytes(byte[] source)
+        {
+            MemoryStream sourceBytes = new MemoryStream(source);
+            MemoryStream decryptedBytes = new MemoryStream();
+            DecryptStream(sourceBytes, decryptedBytes);
+
+            return decryptedBytes.ToArray();
+        }
+    }
+}