public static PkwareTraditionalEncryptionData ForRead(string password, ZipFileEntry header,
byte[] encryptionHeader)
{
var encryptor = new PkwareTraditionalEncryptionData(password);
byte[] plainTextHeader = encryptor.Decrypt(encryptionHeader, encryptionHeader.Length);
if (plainTextHeader[11] != (byte)((header.Crc >> 24) & 0xff))
{
if (!FlagUtility.HasFlag(header.Flags, HeaderFlags.UsePostDataDescriptor))
{
throw new CryptographicException("The password did not match.");
}
if (plainTextHeader[11] != (byte)((header.LastModifiedTime >> 8) & 0xff))
{
throw new CryptographicException("The password did not match.");
}
}
return(encryptor);
}
public override int Read(byte[] buffer, int offset, int count)
{
if (mode == CryptoMode.Encrypt)
{
throw new NotSupportedException("This stream does not encrypt via Read()");
}
if (buffer == null)
{
throw new ArgumentNullException("buffer");
}
byte[] temp = new byte[count];
int readBytes = stream.Read(temp, 0, count);
byte[] decrypted = encryptor.Decrypt(temp, readBytes);
Buffer.BlockCopy(decrypted, 0, buffer, offset, readBytes);
return(readBytes);
}