mcs/class/System.IO.Compression/SharpCompress/Common/Zip/WinzipAesEncryptionData.cs

   1 using System;
   2
   3 namespace SharpCompress.Common.Zip
   4 {
   5     internal class WinzipAesEncryptionData
   6     {
   7         private const int RFC2898_ITERATIONS = 1000;
   8
   9         private byte[] salt;
  10         private WinzipAesKeySize keySize;
  11         private byte[] passwordVerifyValue;
  12         private string password;
  13
  14         private byte[] generatedVerifyValue;
  15
  16         internal WinzipAesEncryptionData(WinzipAesKeySize keySize, byte[] salt, byte[] passwordVerifyValue,
  17                                          string password)
  18         {
  19             this.keySize = keySize;
  20             this.salt = salt;
  21             this.passwordVerifyValue = passwordVerifyValue;
  22             this.password = password;
  23             Initialize();
  24         }
  25
  26         internal byte[] IvBytes { get; set; }
  27         internal byte[] KeyBytes { get; set; }
  28
  29         private int KeySizeInBytes
  30         {
  31             get { return KeyLengthInBytes(keySize); }
  32         }
  33
  34         internal static int KeyLengthInBytes(WinzipAesKeySize keySize)
  35         {
  36             switch (keySize)
  37             {
  38                 case WinzipAesKeySize.KeySize128:
  39                     return 16;
  40                 case WinzipAesKeySize.KeySize192:
  41                     return 24;
  42                 case WinzipAesKeySize.KeySize256:
  43                     return 32;
  44             }
  45             throw new InvalidOperationException();
  46         }
  47
  48         private void Initialize()
  49         {
  50             System.Security.Cryptography.Rfc2898DeriveBytes rfc2898 =
  51                 new System.Security.Cryptography.Rfc2898DeriveBytes(password, salt, RFC2898_ITERATIONS);
  52
  53             KeyBytes = rfc2898.GetBytes(KeySizeInBytes); // 16 or 24 or 32 ???
  54             IvBytes = rfc2898.GetBytes(KeySizeInBytes);
  55             generatedVerifyValue = rfc2898.GetBytes(2);
  56
  57             short verify = BitConverter.ToInt16(passwordVerifyValue, 0);
  58             if (password != null)
  59             {
  60                 short generated = BitConverter.ToInt16(generatedVerifyValue, 0);
  61                 if (verify != generated)
  62                     throw new InvalidFormatException("bad password");
  63             }
  64         }
  65     }
  66 }