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using System;
namespace SharpCompress.Common.Zip
{
internal class WinzipAesEncryptionData
{
private const int RFC2898_ITERATIONS = 1000;
private byte[] salt;
private WinzipAesKeySize keySize;
private byte[] passwordVerifyValue;
private string password;
private byte[] generatedVerifyValue;
internal WinzipAesEncryptionData(WinzipAesKeySize keySize, byte[] salt, byte[] passwordVerifyValue,
string password)
{
this.keySize = keySize;
this.salt = salt;
this.passwordVerifyValue = passwordVerifyValue;
this.password = password;
Initialize();
}
internal byte[] IvBytes { get; set; }
internal byte[] KeyBytes { get; set; }
private int KeySizeInBytes
{
get { return KeyLengthInBytes(keySize); }
}
internal static int KeyLengthInBytes(WinzipAesKeySize keySize)
{
switch (keySize)
{
case WinzipAesKeySize.KeySize128:
return 16;
case WinzipAesKeySize.KeySize192:
return 24;
case WinzipAesKeySize.KeySize256:
return 32;
}
throw new InvalidOperationException();
}
private void Initialize()
{
System.Security.Cryptography.Rfc2898DeriveBytes rfc2898 =
new System.Security.Cryptography.Rfc2898DeriveBytes(password, salt, RFC2898_ITERATIONS);
KeyBytes = rfc2898.GetBytes(KeySizeInBytes); // 16 or 24 or 32 ???
IvBytes = rfc2898.GetBytes(KeySizeInBytes);
generatedVerifyValue = rfc2898.GetBytes(2);
short verify = BitConverter.ToInt16(passwordVerifyValue, 0);
if (password != null)
{
short generated = BitConverter.ToInt16(generatedVerifyValue, 0);
if (verify != generated)
throw new InvalidFormatException("bad password");
}
}
}
}
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