Merge pull request #9 from h5p9sl/master

Added file metadata, and randomized initialization vectors.

Crypto Notepad/AES.cs

@@ -5,17 +5,95 @@
 
 namespace Crypto_Notepad
 {
+    /// <summary>
+    /// This class extracts information needed for decryption from a .cnp file
+    /// </summary>
+    class AESMetadata
+    {
+        /// <summary>
+        /// Offset to actual AES data; size of metadata
+        /// </summary>
+        private int _offsetToData;
+        public int offsetToData
+        {
+            get
+            {
+                return this._offsetToData;
+            }
+        }
+        private byte[] _initialVector;
+        public byte[] initialVector
+        {
+            get
+            {
+                return this._initialVector;
+            }
+        }
+        private byte[] _salt;
+        public byte[] salt
+        {
+            get
+            {
+                return this._salt;
+            }
+        }
+
+        public AESMetadata()
+        {
+            this._initialVector = new byte[16];
+            this._salt = null;
+        }
+
+        public void DeleteMetadataFromBuffer(ref byte[] rawData)
+        {
+            // Possibly unsafe
+            byte[] buffer = new byte[rawData.Length - this.offsetToData];
+            System.Buffer.BlockCopy(rawData, this.offsetToData, buffer, 0, rawData.Length - this.offsetToData);
+            rawData = buffer;
+        }
+
+        public void GetMetadata(byte[] rawData)
+        {
+            int index = 0;
+            // Read initialVector
+            for (int i = 0; index < rawData.Length; index++, i++)
+            {
+                if (rawData[index] == '\0') // Null terminator
+                {
+                    index++;
+                    break;
+                }
+                this.initialVector[i] = rawData[index];
+            }
+            // This is kind of a dirty fix, but it gets the job done
+            // Get length of salt
+            int length = 0;
+            for (int i = index; i < rawData.Length; i++)
+            {
+                if (rawData[i] == '\0') // Null terminator
+                {
+                    index++;
+                    break;
+                }
+                length++;
+            }
+            // Copy bytes into this.salt
+            this._salt = new byte[length];
+            System.Buffer.BlockCopy(rawData, index - 1, this.salt, 0, length);
+
+            this._offsetToData = this.salt.Length + 1 + this.initialVector.Length + 1;
+        }
+    }
+
     class AES
     {
-        public static string Encrypt(string plainText, string password,
+        public static string Encrypt(string plainText, string password, byte[] initialVectorBytes,
         string salt = "Kosher", string hashAlgorithm = "SHA1",
-        int passwordIterations = 2, string initialVector = "OFRna73m*aze01xY",
+        int passwordIterations = 2, int keySize = 256)
-        int keySize = 256)
         {
             if (string.IsNullOrEmpty(plainText))
                 return "";
 
-            byte[] initialVectorBytes = Encoding.ASCII.GetBytes(initialVector);
             byte[] saltValueBytes = Encoding.ASCII.GetBytes(salt);
             byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);
 
@@ -28,10 +106,16 @@ public static string Encrypt(string plainText, string password,
 
             byte[] cipherTextBytes = null;
 
-            using (ICryptoTransform encryptor = symmetricKey.CreateEncryptor
+            using (MemoryStream memStream = new MemoryStream())
-            (keyBytes, initialVectorBytes))
             {
-                using (MemoryStream memStream = new MemoryStream())
+                byte[] nullByte = { 0 };
+                memStream.Write(initialVectorBytes, 0, initialVectorBytes.Length);
+                memStream.Write(nullByte, 0, 1);
+                memStream.Write(saltValueBytes, 0, saltValueBytes.Length);
+                memStream.Write(nullByte, 0, 1);
+
+                using (ICryptoTransform encryptor = symmetricKey.CreateEncryptor
+                (keyBytes, initialVectorBytes))
                 {
                     using (CryptoStream cryptoStream = new CryptoStream
                              (memStream, encryptor, CryptoStreamMode.Write))
@@ -45,24 +129,31 @@ public static string Encrypt(string plainText, string password,
                 }
             }
 
-            symmetricKey.Clear();
+            symmetricKey.Dispose();
             return Convert.ToBase64String(cipherTextBytes);
         }
 
         public static string Decrypt(string cipherText, string password,
-        string salt = "Kosher", string hashAlgorithm = "SHA1",
+        string hashAlgorithm = "SHA1",
-        int passwordIterations = 2, string initialVector = "OFRna73m*aze01xY",
+        int passwordIterations = 2,
         int keySize = 256)
         {
             if (string.IsNullOrEmpty(cipherText))
                 return "";
 
-            byte[] initialVectorBytes = Encoding.ASCII.GetBytes(initialVector);
+            byte[] initialVectorBytes;
-            byte[] saltValueBytes = Encoding.ASCII.GetBytes(salt);
+            byte[] saltValueBytes;
             byte[] cipherTextBytes = Convert.FromBase64String(cipherText);
 
+            // Extract metadata from file
+            AESMetadata metadata = new AESMetadata();
+            metadata.GetMetadata(cipherTextBytes);
+            saltValueBytes = metadata.salt;
+            initialVectorBytes = metadata.initialVector;
+            metadata.DeleteMetadataFromBuffer(ref cipherTextBytes);
+
             PasswordDeriveBytes derivedPassword = new PasswordDeriveBytes
-            (password, saltValueBytes, hashAlgorithm, passwordIterations);
+                (password, saltValueBytes, hashAlgorithm, passwordIterations);
             byte[] keyBytes = derivedPassword.GetBytes(keySize / 8);
 
             RijndaelManaged symmetricKey = new RijndaelManaged();
@@ -71,10 +162,10 @@ public static string Decrypt(string cipherText, string password,
             byte[] plainTextBytes = new byte[cipherTextBytes.Length];
             int byteCount = 0;
 
-            using (ICryptoTransform decryptor = symmetricKey.CreateDecryptor
+            using (MemoryStream memStream = new MemoryStream(cipherTextBytes))
-                     (keyBytes, initialVectorBytes))
             {
-                using (MemoryStream memStream = new MemoryStream(cipherTextBytes))
+                using (ICryptoTransform decryptor = symmetricKey.CreateDecryptor
+                         (keyBytes, initialVectorBytes))
                 {
                     using (CryptoStream cryptoStream
                     = new CryptoStream(memStream, decryptor, CryptoStreamMode.Read))
@@ -84,9 +175,10 @@ public static string Decrypt(string cipherText, string password,
                         cryptoStream.Close();
                     }
                 }
-            }
 
-            symmetricKey.Clear();
+                symmetricKey.Dispose();
+            }
+            
             return Encoding.UTF8.GetString(plainTextBytes, 0, byteCount);
         }
     }

Crypto Notepad/Form1.cs

@@ -51,7 +51,7 @@ void SaltMAC()
                 DialogResult res = new DialogResult();
                 using (new CenterWinDialog(this))
                 {
-                    res = MessageBox.Show("Get The Salt from mac address? (You can edit it by himself in Settings)", "Crypto Notepad",
+                    res = MessageBox.Show("Get The Salt from mac address? (You can change it yourself in Settings)", "Crypto Notepad",
                 MessageBoxButtons.YesNo, MessageBoxIcon.Question);
                 }
 
@@ -88,7 +88,7 @@ void DecryptAES()
             {
                 string opnfile = File.ReadAllText(OpenFile.FileName);
                 string NameWithotPath = Path.GetFileName(OpenFile.FileName);
-                string de = AES.Decrypt(opnfile, publicVar.encryptionKey, ps.TheSalt, ps.HashAlgorithm, ps.PasswordIterations, "16CHARSLONG12345", ps.KeySize);
+                string de = AES.Decrypt(opnfile, publicVar.encryptionKey, ps.HashAlgorithm, ps.PasswordIterations, ps.KeySize);
                 customRTB.Text = de;
 
                 this.Text = appName + NameWithotPath;
@@ -165,7 +165,7 @@ private void openAsotiations()
                 }
                 publicVar.okPressed = false;
 
-                string de = AES.Decrypt(opnfile, publicVar.encryptionKey, ps.TheSalt, ps.HashAlgorithm, ps.PasswordIterations, "16CHARSLONG12345", ps.KeySize);
+                string de = AES.Decrypt(opnfile, publicVar.encryptionKey, ps.HashAlgorithm, ps.PasswordIterations, ps.KeySize);
                 customRTB.Text = de;
 
                 this.Text = appName + NameWithotPath;
@@ -234,8 +234,15 @@ private void saveAsToolStripMenuItem_Click(object sender, EventArgs e)
 
             filename = SaveFile.FileName;
 
+            // Generate random initialization vector
+            RandomNumberGenerator RandNumGen = RNGCryptoServiceProvider.Create();
+            byte[] RandInitVector = new byte[16];
+            RandNumGen.GetNonZeroBytes(RandInitVector);
+
             string noenc = customRTB.Text;
-            string en = AES.Encrypt(customRTB.Text, publicVar.encryptionKey, ps.TheSalt, ps.HashAlgorithm, ps.PasswordIterations, "16CHARSLONG12345", ps.KeySize);
+            string en = AES.Encrypt(customRTB.Text, publicVar.encryptionKey, RandInitVector, ps.TheSalt, ps.HashAlgorithm, ps.PasswordIterations, ps.KeySize);
+            RandNumGen.Dispose();
+
             customRTB.Text = en;
             StreamWriter sw = new StreamWriter(filename);
             int i = customRTB.Lines.Count();
@@ -374,8 +381,15 @@ private void saveToolStripMenuItem1_Click_1(object sender, EventArgs e)
                 publicVar.okPressed = false;
             }
 
+            // Generate random initialization vector
+            RandomNumberGenerator RandNumGen = RNGCryptoServiceProvider.Create();
+            byte[] RandInitVector = new byte[16];
+            RandNumGen.GetNonZeroBytes(RandInitVector);
+
             string noenc = customRTB.Text;
-            string en = AES.Encrypt(customRTB.Text, publicVar.encryptionKey, ps.TheSalt, ps.HashAlgorithm, ps.PasswordIterations, "16CHARSLONG12345", ps.KeySize);
+            string en = AES.Encrypt(customRTB.Text, publicVar.encryptionKey, RandInitVector, ps.TheSalt, ps.HashAlgorithm, ps.PasswordIterations, ps.KeySize);
+            RandNumGen.Dispose();
+
             customRTB.Text = en;
             StreamWriter sw = new StreamWriter(filename);
             int i = customRTB.Lines.Count();
@@ -936,7 +950,7 @@ void AutoLock(bool minimize)
                 OpenFile.FileName = filename;
                 string opnfile = File.ReadAllText(OpenFile.FileName);
                 string NameWithotPath = Path.GetFileName(OpenFile.FileName);
-                string de = AES.Decrypt(opnfile, publicVar.encryptionKey, ps.TheSalt, ps.HashAlgorithm, ps.PasswordIterations, "16CHARSLONG12345", ps.KeySize);
+                string de = AES.Decrypt(opnfile, publicVar.encryptionKey, ps.HashAlgorithm, ps.PasswordIterations, ps.KeySize);
 
                 this.Text = appName + NameWithotPath;
                 filename = OpenFile.FileName;

Crypto Notepad/Form2.cs

@@ -7,6 +7,8 @@ public partial class Form2 : Form
     {
         public Form2()
         {
+            // Initialize to false in case user presses the exit button
+            publicVar.okPressed = false;
             InitializeComponent();
         }