Sample code for AES encryption from Microsoft website

Author: hckr

.gitignore

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+*.swp
+*.*~
+project.lock.json
+.DS_Store
+*.pyc
+nupkg/
+
+# Visual Studio Code
+#.vscode
+
+# Rider
+.idea
+
+# User-specific files
+*.suo
+*.user
+*.userosscache
+*.sln.docstates
+
+# Build results
+[Dd]ebug/
+[Dd]ebugPublic/
+[Rr]elease/
+[Rr]eleases/
+x64/
+x86/
+build/
+bld/
+[Bb]in/
+[Oo]bj/
+[Oo]ut/
+msbuild.log
+msbuild.err
+msbuild.wrn
+
+# Visual Studio 2015
+.vs/

.vscode/launch.json

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+{
+   // Use IntelliSense to find out which attributes exist for C# debugging
+   // Use hover for the description of the existing attributes
+   // For further information visit https://github.com/OmniSharp/omnisharp-vscode/blob/master/debugger-launchjson.md
+   "version": "0.2.0",
+   "configurations": [
+        {
+            "name": ".NET Core Launch (console)",
+            "type": "coreclr",
+            "request": "launch",
+            "preLaunchTask": "build",
+            // If you have changed target frameworks, make sure to update the program path.
+            "program": "${workspaceFolder}/bin/Debug/netcoreapp2.0/padding-oracle-attack.dll",
+            "args": [],
+            "cwd": "${workspaceFolder}",
+            // For more information about the 'console' field, see https://aka.ms/VSCode-CS-LaunchJson-Console
+            "console": "internalConsole",
+            "stopAtEntry": false
+        },
+        {
+            "name": ".NET Core Attach",
+            "type": "coreclr",
+            "request": "attach",
+            "processId": "${command:pickProcess}"
+        }
+    ]
+}

.vscode/tasks.json

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+{
+    "version": "2.0.0",
+    "tasks": [
+        {
+            "label": "build",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "build",
+                "${workspaceFolder}/padding-oracle-attack.csproj",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        },
+        {
+            "label": "publish",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "publish",
+                "${workspaceFolder}/padding-oracle-attack.csproj",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        },
+        {
+            "label": "watch",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "watch",
+                "run",
+                "${workspaceFolder}/padding-oracle-attack.csproj",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        }
+    ]
+}

Program.cs

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+using System;
+using System.IO;
+using System.Security.Cryptography;
+
+namespace Padding_Oracle_Attack
+{
+    class PaddingOracleAttack
+    {
+        public static void Main()
+        {
+            string original = "Here is some data to encrypt!";
+
+            // Create a new instance of the Aes
+            // class.  This generates a new key and initialization
+            // vector (IV).
+            using (Aes myAes = Aes.Create())
+            {
+
+                // Encrypt the string to an array of bytes.
+                byte[] encrypted = EncryptStringToBytes_Aes(original, myAes.Key, myAes.IV);
+
+                // Decrypt the bytes to a string.
+                string roundtrip = DecryptStringFromBytes_Aes(encrypted, myAes.Key, myAes.IV);
+
+                //Display the original data and the decrypted data.
+                Console.WriteLine("Original:   {0}", original);
+                Console.WriteLine("Round Trip: {0}", roundtrip);
+            }
+        }
+        static byte[] EncryptStringToBytes_Aes(string plainText, byte[] Key, byte[] IV)
+        {
+            // Check arguments.
+            if (plainText == null || plainText.Length <= 0)
+                throw new ArgumentNullException("plainText");
+            if (Key == null || Key.Length <= 0)
+                throw new ArgumentNullException("Key");
+            if (IV == null || IV.Length <= 0)
+                throw new ArgumentNullException("IV");
+            byte[] encrypted;
+
+            // Create an Aes object
+            // with the specified key and IV.
+            using (Aes aesAlg = Aes.Create())
+            {
+                aesAlg.Key = Key;
+                aesAlg.IV = IV;
+
+                // Create an encryptor to perform the stream transform.
+                ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
+
+                // Create the streams used for encryption.
+                using (MemoryStream msEncrypt = new MemoryStream())
+                {
+                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
+                    {
+                        using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
+                        {
+                            //Write all data to the stream.
+                            swEncrypt.Write(plainText);
+                        }
+                        encrypted = msEncrypt.ToArray();
+                    }
+                }
+            }
+
+
+            // Return the encrypted bytes from the memory stream.
+            return encrypted;
+
+        }
+
+        static string DecryptStringFromBytes_Aes(byte[] cipherText, byte[] Key, byte[] IV)
+        {
+            // Check arguments.
+            if (cipherText == null || cipherText.Length <= 0)
+                throw new ArgumentNullException("cipherText");
+            if (Key == null || Key.Length <= 0)
+                throw new ArgumentNullException("Key");
+            if (IV == null || IV.Length <= 0)
+                throw new ArgumentNullException("IV");
+
+            // Declare the string used to hold
+            // the decrypted text.
+            string plaintext = null;
+
+            // Create an Aes object
+            // with the specified key and IV.
+            using (Aes aesAlg = Aes.Create())
+            {
+                aesAlg.Key = Key;
+                aesAlg.IV = IV;
+
+                // Create a decryptor to perform the stream transform.
+                ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);
+
+                // Create the streams used for decryption.
+                using (MemoryStream msDecrypt = new MemoryStream(cipherText))
+                {
+                    using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
+                    {
+                        using (StreamReader srDecrypt = new StreamReader(csDecrypt))
+                        {
+
+                            // Read the decrypted bytes from the decrypting stream
+                            // and place them in a string.
+                            plaintext = srDecrypt.ReadToEnd();
+                        }
+                    }
+                }
+
+            }
+
+            return plaintext;
+        }
+    }
+}

padding-oracle-attack.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp2.0</TargetFramework>
+  </PropertyGroup>
+
+</Project>