Update StringCipher.cs

Ombi/Ombi.Helpers/StringCipher.cs

@@ -1,19 +1,12 @@
-using System;
+using System;
 using System.IO;
-using System.Linq;
 using System.Security.Cryptography;
 using System.Text;
 
 namespace Ombi.Helpers
 {
-    public class StringCipher
+    public static class StringCipher
     {
-        // This constant determines the number of iterations for the password bytes generation function.
-        private const int DerivationIterations = 1000;
-        // This constant is used to determine the keysize of the encryption algorithm in bits.
-        // We divide this by 8 within the code below to get the equivalent number of bytes.
-        private const int Keysize = 256;
-
         /// <summary>
         /// Decrypts the specified cipher text.
         /// </summary>
@@ -22,39 +15,32 @@ namespace Ombi.Helpers
         /// <returns></returns>
         public static string Decrypt(string cipherText, string passPhrase)
         {
-            // Get the complete stream of bytes that represent:
-            // [32 bytes of Salt] + [32 bytes of IV] + [n bytes of CipherText]
-            var cipherTextBytesWithSaltAndIv = Convert.FromBase64String(cipherText);
-            // Get the saltbytes by extracting the first 32 bytes from the supplied cipherText bytes.
-            var saltStringBytes = cipherTextBytesWithSaltAndIv.Take(Keysize / 8).ToArray();
-            // Get the IV bytes by extracting the next 32 bytes from the supplied cipherText bytes.
-            var ivStringBytes = cipherTextBytesWithSaltAndIv.Skip(Keysize / 8).Take(Keysize / 8).ToArray();
-            // Get the actual cipher text bytes by removing the first 64 bytes from the cipherText string.
-            var cipherTextBytes = cipherTextBytesWithSaltAndIv.Skip((Keysize / 8) * 2).Take(cipherTextBytesWithSaltAndIv.Length - ((Keysize / 8) * 2)).ToArray();
+            var fullCipher = Convert.FromBase64String(cipherText);
+
+            var iv = new byte[16];
+            var cipher = new byte[16];
+
+            Buffer.BlockCopy(fullCipher, 0, iv, 0, iv.Length);
+            Buffer.BlockCopy(fullCipher, iv.Length, cipher, 0, iv.Length);
+            var key = Encoding.UTF8.GetBytes(passPhrase);
 
-            using (var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations))
+            using (var aesAlg = Aes.Create())
             {
-                var keyBytes = password.GetBytes(Keysize / 8);
-                var aes = Aes.Create();
-                using (var symmetricKey = new RijndaelManaged())
+                using (var decryptor = aesAlg.CreateDecryptor(key, iv))
                 {
-                    symmetricKey.BlockSize = 256;
-                    symmetricKey.Mode = CipherMode.CBC;
-                    symmetricKey.Padding = PaddingMode.PKCS7;
-                    using (var decryptor = symmetricKey.CreateDecryptor(keyBytes, ivStringBytes))
+                    string result;
+                    using (var msDecrypt = new MemoryStream(cipher))
                     {
-                        using (var memoryStream = new MemoryStream(cipherTextBytes))
+                        using (var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                         {
-                            using (var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
+                            using (var srDecrypt = new StreamReader(csDecrypt))
                             {
-                                var plainTextBytes = new byte[cipherTextBytes.Length];
-                                var decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
-                                memoryStream.Close();
-                                cryptoStream.Close();
-                                return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
+                                result = srDecrypt.ReadToEnd();
                             }
                         }
                     }
+
+                    return result;
                 }
             }
         }
@@ -67,54 +53,33 @@ namespace Ombi.Helpers
         /// <returns></returns>
         public static string Encrypt(string plainText, string passPhrase)
         {
-            // Salt and IV is randomly generated each time, but is preprended to encrypted cipher text
-            // so that the same Salt and IV values can be used when decrypting.  
-            var saltStringBytes = Generate256BitsOfRandomEntropy();
-            var ivStringBytes = Generate256BitsOfRandomEntropy();
-            var plainTextBytes = Encoding.UTF8.GetBytes(plainText);
-            using (var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations))
+            var key = Encoding.UTF8.GetBytes(passPhrase);
+
+            using (var aesAlg = Aes.Create())
             {
-                var keyBytes = password.GetBytes(Keysize / 8);
-                using (var symmetricKey = new RijndaelManaged())
+                using (var encryptor = aesAlg.CreateEncryptor(key, aesAlg.IV))
                 {
-                    symmetricKey.BlockSize = 256;
-                    symmetricKey.Mode = CipherMode.CBC;
-                    symmetricKey.Padding = PaddingMode.PKCS7;
-                    using (var encryptor = symmetricKey.CreateEncryptor(keyBytes, ivStringBytes))
+                    using (var msEncrypt = new MemoryStream())
                     {
-                        using (var memoryStream = new MemoryStream())
+                        using (var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
+                        using (var swEncrypt = new StreamWriter(csEncrypt))
                         {
-                            using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
-                            {
-                                cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
-                                cryptoStream.FlushFinalBlock();
-                                // Create the final bytes as a concatenation of the random salt bytes, the random iv bytes and the cipher bytes.
-                                var cipherTextBytes = saltStringBytes;
-                                cipherTextBytes = cipherTextBytes.Concat(ivStringBytes).ToArray();
-                                cipherTextBytes = cipherTextBytes.Concat(memoryStream.ToArray()).ToArray();
-                                memoryStream.Close();
-                                cryptoStream.Close();
-                                return Convert.ToBase64String(cipherTextBytes);
-                            }
+                            swEncrypt.Write(plainText);
                         }
+
+                        var iv = aesAlg.IV;
+
+                        var decryptedContent = msEncrypt.ToArray();
+
+                        var result = new byte[iv.Length + decryptedContent.Length];
+
+                        Buffer.BlockCopy(iv, 0, result, 0, iv.Length);
+                        Buffer.BlockCopy(decryptedContent, 0, result, iv.Length, decryptedContent.Length);
+
+                        return Convert.ToBase64String(result);
                     }
                 }
             }
         }
-
-        /// <summary>
-        /// Generate256s the bits of random entropy.
-        /// </summary>
-        /// <returns></returns>
-        private static byte[] Generate256BitsOfRandomEntropy()
-        {
-            var randomBytes = new byte[32]; // 32 Bytes will give us 256 bits.
-            using (var rngCsp = new RNGCryptoServiceProvider())
-            {
-                // Fill the array with cryptographically secure random bytes.
-                rngCsp.GetBytes(randomBytes);
-            }
-            return randomBytes;
-        }
     }
 }