Stream CreateAndInitDecryptionStream(Stream baseStream, ZipEntry entry)
{
CryptoStream result = null;
if (entry.Version < ZipConstants.VERSION_STRONG_ENCRYPTION
|| (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, iv), CryptoStreamMode.Read);
CheckClassicPassword(result, entry);
}
else {
throw new ZipException("Decryption method not supported");
}
return result;
}
Stream CreateAndInitEncryptionStream(Stream baseStream, ZipEntry entry)
{
CryptoStream result = null;
if (entry.Version < ZipConstants.VERSION_STRONG_ENCRYPTION
|| (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.CreateEncryptor(key, iv), CryptoStreamMode.Write);
if (entry.Crc < 0 || (entry.Flags & 8) != 0) {
WriteEncryptionHeader(result, entry.DosTime << 16);
}
else {
WriteEncryptionHeader(result, entry.Crc);
}
}
return result;
}
// Perform the initial read on an entry which may include
// reading encryption headers and setting up inflation.
int InitialRead(byte[] destination, int offset, int count)
{
if (entry.Version > ZipConstants.VERSION_MADE_BY) {
throw new ZipException("Libray cannot extract this entry version required (" + entry.Version.ToString() + ")");
}
// test for encryption
if (entry.IsCrypted) {
if (password == null) {
throw new ZipException("No password set.");
}
// Generate and set crypto transform...
PkzipClassicManaged managed = new PkzipClassicManaged();
byte[] key = PkzipClassic.GenerateKeys(Encoding.ASCII.GetBytes(password));
inputBuffer.CryptoTransform = managed.CreateDecryptor(key, null);
byte[] cryptbuffer = new byte[ZipConstants.CRYPTO_HEADER_SIZE];
inputBuffer.ReadClearTextBuffer(cryptbuffer, 0, ZipConstants.CRYPTO_HEADER_SIZE);
if ((flags & 8) == 0) {
if (cryptbuffer[ZipConstants.CRYPTO_HEADER_SIZE - 1] != (byte)(entry.Crc >> 24)) {
throw new ZipException("Invalid password");
}
}
else {
if (cryptbuffer[ZipConstants.CRYPTO_HEADER_SIZE - 1] != (byte)((entry.DosTime >> 8) & 0xff)) {
throw new ZipException("Invalid password");
}
}
if (csize >= ZipConstants.CRYPTO_HEADER_SIZE) {
csize -= ZipConstants.CRYPTO_HEADER_SIZE;
}
}
else {
inputBuffer.CryptoTransform = null;
}
if (method == (int)CompressionMethod.Deflated && inputBuffer.Available > 0) {
inputBuffer.SetInflaterInput(inf);
}
internalReader = new ReaderDelegate(BodyRead);
return BodyRead(destination, offset, count);
}
