/// <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;
}
}
Stream CreateAndInitEncryptionStream(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");
}
// 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>
/// Returns a binary array of decrypted data for the given parameters.
/// </summary>
public static byte[] Decrypt(this byte[] source, int startIndex, int length, byte[] key, byte[] IV, CipherStrength strength)
{
if (strength == CipherStrength.None)
return source;
// Performs requested levels of decryption.
if (strength >= CipherStrength.Level6)
{
source = new Pkzip.PkzipClassicManaged().Decrypt(source, startIndex, length, key, IV);
startIndex = 0;
length = source.Length;
}
if (strength >= CipherStrength.Level5)
{
source = Deobfuscate(source, startIndex, length, key);
startIndex = 0;
length = source.Length;
}
if (strength >= CipherStrength.Level4)
{
source = new RijndaelManaged().Decrypt(source, startIndex, length, key, IV);
startIndex = 0;
length = source.Length;
}
if (strength >= CipherStrength.Level3)
{
source = new RC2CryptoServiceProvider().Decrypt(source, startIndex, length, key, IV);
startIndex = 0;
length = source.Length;
}
if (strength >= CipherStrength.Level2)
{
source = new TripleDESCryptoServiceProvider().Decrypt(source, startIndex, length, key, IV);
startIndex = 0;
length = source.Length;
}
return Crypt(source, startIndex, length, key);
}
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;
}
/// <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
}