/// <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>
int InitialRead(byte[] destination, int offset, int count)
{
if ( !CanDecompressEntry ) {
throw new ZipException("Library cannot extract this entry. Version required is (" + entry.Version.ToString() + ")");
}
// 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 ((csize > 0) || ((flags & (int)GeneralBitFlags.Descriptor) != 0)) {
if ((method == (int)CompressionMethod.Deflated) && (inputBuffer.Available > 0)) {
inputBuffer.SetInflaterInput(inf);
}
internalReader = new ReadDataHandler(BodyRead);
return BodyRead(destination, offset, count);
}
else {
internalReader = new ReadDataHandler(ReadingNotAvailable);
return 0;
}
}
/// <summary>
/// Initializes encryption keys based on given <paramref name="password"/>.
/// </summary>
/// <param name="password">The password.</param>
protected void InitializePassword(string password)
{
#if NETCF_1_0
keys = new uint[] {
0x12345678,
0x23456789,
0x34567890
};
byte[] rawPassword = ZipConstants.ConvertToArray(password);
for (int i = 0; i < rawPassword.Length; ++i) {
UpdateKeys((byte)rawPassword[i]);
}
#else
PkzipClassicManaged pkManaged = new PkzipClassicManaged();
byte[] key = PkzipClassic.GenerateKeys(ZipConstants.ConvertToArray(password));
cryptoTransform_ = pkManaged.CreateEncryptor(key, null);
#endif
}
