Stream CreateAndInitDecryptionStream( Stream baseStream, BlubbZipEntry entry ) {
CryptoStream result = null;
if( ( entry.Version < BlubbZipConstants.VersionStrongEncryption )
|| ( entry.Flags & (int)GeneralBitFlags.StrongEncryption ) == 0 ) {
PkblubbClassicManaged classicManaged = new PkblubbClassicManaged();
OnKeysRequired( entry.Name );
if( HaveKeys == false ) {
throw new BlubbZipException( "No password available for encrypted stream" );
}
result = new CryptoStream( baseStream, classicManaged.CreateDecryptor( key, null ), CryptoStreamMode.Read );
CheckClassicPassword( result, entry );
} else {
throw new BlubbZipException( "Decryption method not supported" );
}
return result;
}
Stream CreateAndInitEncryptionStream( Stream baseStream, BlubbZipEntry entry ) {
CryptoStream result = null;
if( ( entry.Version < BlubbZipConstants.VersionStrongEncryption )
|| ( entry.Flags & (int)GeneralBitFlags.StrongEncryption ) == 0 ) {
PkblubbClassicManaged classicManaged = new PkblubbClassicManaged();
OnKeysRequired( entry.Name );
if( HaveKeys == false ) {
throw new BlubbZipException( "No password available for encrypted stream" );
}
// Closing a CryptoStream will close the base stream as well so wrap it in an UncompressedStream
// which doesnt do this.
result = new CryptoStream( new UncompressedStream( baseStream ),
classicManaged.CreateEncryptor( key, null ), CryptoStreamMode.Write );
if( ( entry.Crc < 0 ) || ( entry.Flags & 8 ) != 0 ) {
WriteEncryptionHeader( result, entry.DosTime << 16 );
} else {
WriteEncryptionHeader( result, entry.Crc );
}
}
return result;
}
/// <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 BlubbZipException( "Library cannot extract this entry. Version required is (" + entry.Version.ToString() + ")" );
}
// Handle encryption if required.
if( entry.IsCrypted ) {
if( password == null ) {
throw new BlubbZipException( "No password set." );
}
// Generate and set crypto transform...
PkblubbClassicManaged managed = new PkblubbClassicManaged();
byte[] key = PkblubbClassic.GenerateKeys( BlubbZipConstants.ConvertToArray( password ) );
inputBuffer.CryptoTransform = managed.CreateDecryptor( key, null );
byte[] cryptbuffer = new byte[ BlubbZipConstants.CryptoHeaderSize ];
inputBuffer.ReadClearTextBuffer( cryptbuffer, 0, BlubbZipConstants.CryptoHeaderSize );
if( cryptbuffer[ BlubbZipConstants.CryptoHeaderSize - 1 ] != entry.CryptoCheckValue ) {
throw new BlubbZipException( "Invalid password" );
}
if( csize >= BlubbZipConstants.CryptoHeaderSize ) {
csize -= BlubbZipConstants.CryptoHeaderSize;
} else if( ( entry.Flags & (int)GeneralBitFlags.Descriptor ) == 0 ) {
throw new BlubbZipException( string.Format( "Entry compressed size {0} too small for encryption", csize ) );
}
} else {
inputBuffer.CryptoTransform = null;
}
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;
}
}
