/// <summary>
/// Perform the initial read on an entry which may include
/// reading encryption headers and setting up inflation.
/// </summary>
/// <param name="destination">The destination to fill with data read.</param>
/// <param name="offset">The offset to start reading at.</param>
/// <param name="count">The maximum number of bytes to read.</param>
/// <returns>The actual number of bytes read.</returns>
private int InitialRead(byte[] destination, int offset, int count)
{
if (!CanDecompressEntry)
{
throw new ZipException("Library cannot extract this entry. Version required is (" + entry.Version + ")");
}
// Handle encryption if required.
if (entry.IsCrypted)
{
#if NETCF_1_0
throw new ZipException("Encryption not supported for Compact Framework 1.0");
#else
if (password == null)
{
throw new ZipException("No password set.");
}
// Generate and set crypto transform...
PkzipClassicManaged managed = new PkzipClassicManaged();
byte[] key = PkzipClassic.GenerateKeys(ZipConstants.ConvertToArray(password));
inputBuffer.CryptoTransform = managed.CreateDecryptor(key, null);
byte[] cryptbuffer = new byte[ZipConstants.CryptoHeaderSize];
inputBuffer.ReadClearTextBuffer(cryptbuffer, 0, ZipConstants.CryptoHeaderSize);
if (cryptbuffer[ZipConstants.CryptoHeaderSize - 1] != entry.CryptoCheckValue)
{
throw new ZipException("Invalid password");
}
if (csize >= ZipConstants.CryptoHeaderSize)
{
csize -= ZipConstants.CryptoHeaderSize;
}
else if ((entry.Flags & (int) GeneralBitFlags.Descriptor) == 0)
{
throw new ZipException(string.Format("Entry compressed size {0} too small for encryption", csize));
}
#endif
}
else
{
#if !NETCF_1_0
inputBuffer.CryptoTransform = null;
#endif
}
if ((method == (int) CompressionMethod.Deflated) && (inputBuffer.Available > 0))
{
inputBuffer.SetInflaterInput(inf);
}
internalReader = BodyRead;
return BodyRead(destination, offset, count);
}
private Stream CreateAndInitDecryptionStream(Stream baseStream, ZipEntry entry)
{
CryptoStream result = null;
if ((entry.Version < ZipConstants.VersionStrongEncryption)
|| (entry.Flags & (int) GeneralBitFlags.StrongEncryption) == 0)
{
PkzipClassicManaged classicManaged = new PkzipClassicManaged();
OnKeysRequired(entry.Name);
if (HaveKeys == false)
{
throw new ZipException("No password available for encrypted stream");
}
result = new CryptoStream(baseStream, classicManaged.CreateDecryptor(key, null), CryptoStreamMode.Read);
CheckClassicPassword(result, entry);
}
else
{
throw new ZipException("Decryption method not supported");
}
return result;
}