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	15d ago
Date Last Modified	15d ago

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using System; using System.IO; 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; /// <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(aes.BlockSize / 8); key = aes.Key = generator.GetBytes(aes.KeySize / 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(secretMessage); } cipherText = cipherStream.ToArray(); } } var z = new byte[key.Length + iv.Length]; iv.CopyTo(z, 0); key.CopyTo(z, iv.Length); //Assemble encrypted message and add authentication using (var hmac = new HMACSHA256(z)) 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(z, 0, z.Length); 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); var compare = 0; for (var i = 0; i < sig.Length; i++) compare |= Sig[i] ^ sig[i]; if (compare != 0) return null; //get the salt var 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 var z = new byte[key.Length + iv.Length]; iv.CopyTo(z, 0); key.CopyTo(z, iv.Length); using (var hmac = new HMACSHA256(z)) { var sentTag = new byte[hmac.HashSize / 8]; //Calculate Tag var calcTag = hmac.ComputeHash(encryptedMessage, 0, encryptedMessage.Length - sentTag.Length); //Grab Sent Tag Array.Copy(encryptedMessage, encryptedMessage.Length - sentTag.Length, sentTag, 0, sentTag.Length); //Compare Tag with constant time comparison compare = 0; for (var i = 0; i < sentTag.Length; i++) compare |= sentTag[i] ^ calcTag[i]; //if message doesn't authenticate return null if (compare != 0) 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(z, 0, z.Length); Array.Clear(key, 0, key.Length); Array.Clear(iv, 0, iv.Length); //Return Plain Text return 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 or the password is invalid!"); } } } } BFS.Clipboard.Clear(); BFS.ClipboardFusion.ResumeClipboardListener(); return null; } }