AES Encryption\Decryption

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Description	This script encrypts and decrypts text using the AES256 algorithm. For security, it doesn't use the clipboard at all.
Language	C#
Minimum Version	5.6+
Created By	jackz98
Contributors	-
Date Created	Oct 8, 2019
Date Last Modified	Nov 7, 2019

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using System; using System.IO; using System.IO.Compression; using System.Security.Cryptography; using System.Text; /// <summary> /// C# AES256 by jackz98 /// </summary> public static class SimpleAES256 { private static byte[] Sig = new byte[4] { 0x6a, 0x39, 0x1b, 0xf3 }; private static readonly int SaltByteSize = 8; private static readonly int Iterations = 10025; private static bool CompareBytes(byte[] a, byte[] b) { var compare = 0; if (a.Length == b.Length) { for (var i = 0; i < a.Length; i++) compare |= a[i] ^ b[i]; return compare == 0 ? true : false; } return false; } private static byte[] CompressBytes(byte[] bytes) { using (MemoryStream compressStream = new MemoryStream()) { using (var zipStream = new GZipStream(compressStream, CompressionMode.Compress)) zipStream.Write(bytes, 0, bytes.Length); return compressStream.ToArray(); } } private static byte[] DecompressBytes(byte[] bytes) { using (var compressStream = new MemoryStream(bytes)) { using (var zipStream = new GZipStream(compressStream, CompressionMode.Decompress)) { using (var resultStream = new MemoryStream()) { zipStream.CopyTo(resultStream); return resultStream.ToArray(); } } } } /// <summary> /// Encrypted Format: /// +------+---------+-----------------------------------+---------+ /// |SIG(4)| Salt(8) | Ciphertext... | MAC(32) | /// +------+---------+-----------------------------------+---------+ /// </summary> /// <param name="secretMessage">The message to be encrypted.</param> /// <param name="passwords">The password.</param> /// <returns></returns> public static byte[] Encrypt(byte[] secretMessage, string password) { byte[] sigSalt = new byte[Sig.Length + SaltByteSize]; Array.Copy(Sig, sigSalt, Sig.Length); byte[] cipherText; byte[] key; byte[] iv; using (var aes = new AesManaged { KeySize = 256, BlockSize = 128, Mode = CipherMode.CBC, Padding = PaddingMode.PKCS7 }) { using (var generator = new Rfc2898DeriveBytes(password, SaltByteSize, Iterations)) { var salt = generator.Salt; iv = aes.IV = generator.GetBytes(128 / 8); key = aes.Key = generator.GetBytes(256 / 8); //add salt to sigSalt Array.Copy(salt, 0, sigSalt, Sig.Length, salt.Length); } using (var encrypter = aes.CreateEncryptor()) using (var cipherStream = new MemoryStream()) { using (var cryptoStream = new CryptoStream(cipherStream, encrypter, CryptoStreamMode.Write)) using (var binaryWriter = new BinaryWriter(cryptoStream)) { binaryWriter.Write(CompressBytes(secretMessage)); } cipherText = cipherStream.ToArray(); } } //Assemble encrypted message and add authentication using (var hmac = new HMACSHA256(key)) using (var encryptedStream = new MemoryStream()) { using (var binaryWriter = new BinaryWriter(encryptedStream)) { //Prepend sigSalt binaryWriter.Write(sigSalt); //Write Ciphertext binaryWriter.Write(cipherText); binaryWriter.Flush(); //Authenticate all data var tag = hmac.ComputeHash(encryptedStream.ToArray()); //Postpend tag binaryWriter.Write(tag); } Array.Clear(key, 0, key.Length); Array.Clear(iv, 0, iv.Length); return encryptedStream.ToArray(); } } public static byte[] Decrypt(byte[] encryptedMessage, string password) { //if message length is to small just return null if (encryptedMessage.Length < 32 + Sig.Length + SaltByteSize) return null; //check the sig byte[] sig = new byte[4]; Array.Copy(encryptedMessage, sig, 4); if (!CompareBytes(sig, Sig)) { return null; } //get the salt byte[] salt = new byte[SaltByteSize]; Array.Copy(encryptedMessage, Sig.Length, salt, 0, salt.Length); //compute the key and iv byte[] key; byte[] iv; using (var generator = new Rfc2898DeriveBytes(password, salt, Iterations)) { iv = generator.GetBytes(128 / 8); key = generator.GetBytes(256 / 8); } //vertify the mac using (var hmac = new HMACSHA256(key)) { //Calculate Tag byte[] calcTag = hmac.ComputeHash(encryptedMessage, 0, encryptedMessage.Length - 32); //Grab Sent Tag byte[] sentTag = new byte[32]; Array.Copy(encryptedMessage, encryptedMessage.Length - sentTag.Length, sentTag, 0, 32); if (!CompareBytes(sentTag, calcTag)) return null; } //decrypt the cipher text using (var aes = new AesManaged { KeySize = 256, BlockSize = 128, Mode = CipherMode.CBC, Padding = PaddingMode.PKCS7, IV = iv, Key = key }) { using (var decrypter = aes.CreateDecryptor()) using (var plainTextStream = new MemoryStream()) { using (var decrypterStream = new CryptoStream(plainTextStream, decrypter, CryptoStreamMode.Write)) using (var binaryWriter = new BinaryWriter(decrypterStream)) { //Decrypt Cipher Text from Message binaryWriter.Write( encryptedMessage, Sig.Length + salt.Length, encryptedMessage.Length - Sig.Length - salt.Length - 32 ); } Array.Clear(key, 0, key.Length); Array.Clear(iv, 0, iv.Length); //Return Plain Text return DecompressBytes(plainTextStream.ToArray()); } } } } // The 'text' parameter will contain the text from the: // - Current Clipboard when run by HotKey // - History Item when run from the History Menu // The returned string will be: // - Placed directly on the Clipboard // - Ignored by ClipboardFusion if it is 'null' public static class ClipboardFusionHelper { private static string AddNewLine(string s) { StringBuilder sb = new StringBuilder(s); for (int i = (s.Length / 64) * 64; i >= 64; i -= 64) sb.Insert(i, Environment.NewLine); return sb.ToString(); } public static string ProcessText(string text) { // your code goes here BFS.ClipboardFusion.PauseClipboardListener(); text = BFS.Clipboard.CopyText(); if (BFS.Clipboard.HasText()) { string a = BFS.Dialog.GetUserInputListViewWithFilter("AES Encryption/Decryption", new string[2] { "Encryption", "Decryption" }); if (a == "Encryption") { string pass = BFS.Dialog.GetUserInput("Encryption: Input your password here!", ""); if (pass != "") { string res = AddNewLine(System.Convert.ToBase64String(SimpleAES256.Encrypt(System.Text.Encoding.Default.GetBytes(text), pass))); BFS.Clipboard.PasteText(res); } } else if (a != "") { string pass = BFS.Dialog.GetUserInput("Decryption: Input your password here!", ""); if (pass != "") { try { string res = Encoding.Default.GetString(SimpleAES256.Decrypt(System.Convert.FromBase64String(text), pass)); BFS.Clipboard.PasteText(res); } catch (Exception) { BFS.Dialog.ShowMessageError("Decryption Failed: malformated text, corrupted message or wrong password!"); } } } } BFS.Clipboard.Clear(); BFS.ClipboardFusion.ResumeClipboardListener(); return null; } }