private void _WriteFileData(ZipCrypto cipher, System.IO.Stream s)
{
// Read in the data from the input stream (often a file in the filesystem),
// and write it to the output stream, calculating a CRC on it as we go.
// We will also deflate and encrypt as necessary.
Stream input = null;
CrcCalculatorStream input1 = null;
CountingStream counter = null;
try {
// s.Position may fail on some write-only streams, eg stdout or System.Web.HttpResponseStream
// We swallow that exception, because we don't care!
this.__FileDataPosition = s.Position;
} catch{}
try
{
// get the original stream:
if (_sourceStream != null)
{
_sourceStream.Position = 0;
input = _sourceStream;
}
else
{
input = System.IO.File.OpenRead(LocalFileName);
}
// wrap a CRC Calculator Stream around the raw input stream.
input1 = new CrcCalculatorStream(input);
// wrap a counting stream around the raw output stream:
counter = new CountingStream(s);
// maybe wrap an encrypting stream around that:
Stream output1 = (Encryption == EncryptionAlgorithm.PkzipWeak) ?
(Stream)(new ZipCipherStream(counter, cipher, CryptoMode.Encrypt)) : counter;
// maybe wrap a DeflateStream around that
Stream output2 = null;
bool mustCloseDeflateStream = false;
if (CompressionMethod == 0x08)
{
output2 = new DeflateStream(output1, CompressionMode.Compress, true);
mustCloseDeflateStream = true;
}
else
output2 = output1;
// as we emit the file, we maybe deflate, then maybe encrypt, then write the bytes.
byte[] buffer = new byte[READBLOCK_SIZE];
int n = input1.Read(buffer, 0, READBLOCK_SIZE);
while (n > 0)
{
output2.Write(buffer, 0, n);
n = input1.Read(buffer, 0, READBLOCK_SIZE);
}
// by calling Close() on the deflate stream, we write the footer bytes, as necessary.
if (mustCloseDeflateStream)
output2.Close();
}
finally
{
if (_sourceStream == null && input != null)
{
input.Close();
input.Dispose();
}
}
_UncompressedSize = input1.TotalBytesSlurped;
_CompressedSize = counter.BytesWritten;
_Crc32 = input1.Crc32;
if ((_Password != null) && (Encryption == EncryptionAlgorithm.PkzipWeak))
{
_CompressedSize += 12; // 12 extra bytes for the encryption header
}
int i = 8;
_EntryHeader[i++] = (byte)(CompressionMethod & 0x00FF);
_EntryHeader[i++] = (byte)((CompressionMethod & 0xFF00) >> 8);
i = 14;
// CRC - the correct value now
_EntryHeader[i++] = (byte)(_Crc32 & 0x000000FF);
_EntryHeader[i++] = (byte)((_Crc32 & 0x0000FF00) >> 8);
_EntryHeader[i++] = (byte)((_Crc32 & 0x00FF0000) >> 16);
_EntryHeader[i++] = (byte)((_Crc32 & 0xFF000000) >> 24);
// CompressedSize - the correct value now
_EntryHeader[i++] = (byte)(_CompressedSize & 0x000000FF);
_EntryHeader[i++] = (byte)((_CompressedSize & 0x0000FF00) >> 8);
_EntryHeader[i++] = (byte)((_CompressedSize & 0x00FF0000) >> 16);
_EntryHeader[i++] = (byte)((_CompressedSize & 0xFF000000) >> 24);
// UncompressedSize - the correct value now
_EntryHeader[i++] = (byte)(_UncompressedSize & 0x000000FF);
_EntryHeader[i++] = (byte)((_UncompressedSize & 0x0000FF00) >> 8);
_EntryHeader[i++] = (byte)((_UncompressedSize & 0x00FF0000) >> 16);
_EntryHeader[i++] = (byte)((_UncompressedSize & 0xFF000000) >> 24);
// workitem 6414
if (s.CanSeek)
{
// seek in the raw output stream, to the beginning of the header for this entry.
s.Seek(this._RelativeOffsetOfHeader, System.IO.SeekOrigin.Begin);
// finally, write the updated header to the output stream
s.Write(_EntryHeader, 0, _EntryHeader.Length);
// adjust the count on the CountingStream as necessary
var s1 = s as CountingStream;
if (s1 != null) s1.Adjust(_EntryHeader.Length);
// seek in the raw output stream, to the end of the file data for this entry
s.Seek(_CompressedSize, System.IO.SeekOrigin.Current);
}
else
{
// eg, ASP.NET Response.OutputStream, or stdout
if ((_BitField & 0x0008) != 0x0008)
throw new ZipException("Logic error.");
byte[] Descriptor = new byte[16];
i = 0;
// signature
int sig = ZipConstants.ZipEntryDataDescriptorSignature;
Descriptor[i++] = (byte)(sig & 0x000000FF);
Descriptor[i++] = (byte)((sig & 0x0000FF00) >> 8);
Descriptor[i++] = (byte)((sig & 0x00FF0000) >> 16);
Descriptor[i++] = (byte)((sig & 0xFF000000) >> 24);
// CRC - the correct value now
Descriptor[i++] = (byte)(_Crc32 & 0x000000FF);
Descriptor[i++] = (byte)((_Crc32 & 0x0000FF00) >> 8);
Descriptor[i++] = (byte)((_Crc32 & 0x00FF0000) >> 16);
Descriptor[i++] = (byte)((_Crc32 & 0xFF000000) >> 24);
// CompressedSize - the correct value now
Descriptor[i++] = (byte)(_CompressedSize & 0x000000FF);
Descriptor[i++] = (byte)((_CompressedSize & 0x0000FF00) >> 8);
Descriptor[i++] = (byte)((_CompressedSize & 0x00FF0000) >> 16);
Descriptor[i++] = (byte)((_CompressedSize & 0xFF000000) >> 24);
// UncompressedSize - the correct value now
Descriptor[i++] = (byte)(_UncompressedSize & 0x000000FF);
Descriptor[i++] = (byte)((_UncompressedSize & 0x0000FF00) >> 8);
Descriptor[i++] = (byte)((_UncompressedSize & 0x00FF0000) >> 16);
Descriptor[i++] = (byte)((_UncompressedSize & 0xFF000000) >> 24);
// finally, write the updated header to the output stream
s.Write(Descriptor, 0, Descriptor.Length);
}
}
private Int32 _ExtractOne(System.IO.Stream output, ZipCrypto cipher)
{
System.IO.Stream input = this.ArchiveStream;
// seek to the beginning of the file data in the stream
input.Seek(this.__FileDataPosition, System.IO.SeekOrigin.Begin);
// to validate the CRC.
Int32 CrcResult = 0;
byte[] bytes = new byte[READBLOCK_SIZE];
// The extraction process varies depending on how the entry was stored.
// It could have been encrypted, and it coould have been compressed, or both, or
// neither. So we need to check both the encryption flag and the compression flag,
// and take the proper action in all cases.
int LeftToRead = (CompressionMethod == 0x08) ? this.UncompressedSize : this._CompressedFileDataSize;
// get a stream that either decrypts or not.
Stream input2 = (Encryption == EncryptionAlgorithm.PkzipWeak)
? new ZipCipherStream(input, cipher, CryptoMode.Decrypt)
: input;
// using the above, now we get a stream that either decompresses or not.
Stream input3 = (CompressionMethod == 0x08)
? new DeflateStream(input2, CompressionMode.Decompress, true)
: input2;
//var out2 = new CrcCalculatorStream(output, LeftToRead);
// as we read, we maybe decrypt, and then we maybe decompress. Then we write.
using (var s1 = new CrcCalculatorStream(input3))
{
while (LeftToRead > 0)
{
int len = (LeftToRead > bytes.Length) ? bytes.Length : LeftToRead;
int n = s1.Read(bytes, 0, len);
_CheckRead(n);
output.Write(bytes, 0, n);
LeftToRead -= n;
}
CrcResult = s1.Crc32;
}
return CrcResult;
}
private ZipCrypto SetupCipher(string password)
{
ZipCrypto cipher = null;
// decrypt the file header data here if necessary.
if (Encryption == EncryptionAlgorithm.PkzipWeak)
{
if (password == null)
throw new BadPasswordException("This entry requires a password.");
cipher = new ZipCrypto();
cipher.InitCipher(password);
// Decrypt the header. This has a side effect of "further initializing the
// encryption keys" in the traditional zip encryption.
byte[] DecryptedHeader = cipher.DecryptMessage(_WeakEncryptionHeader, _WeakEncryptionHeader.Length);
// CRC check
// According to the pkzip spec, the final byte in the decrypted header
// is the highest-order byte in the CRC. We check it here.
if (DecryptedHeader[11] != (byte)((_Crc32 >> 24) & 0xff))
{
// In the case that bit 3 of the general purpose bit flag is set to indicate
// the presence of an 'Extended File Header', the last byte of the decrypted
// header is sometimes compared with the high-order byte of the lastmodified
// time, and not the CRC, to verify the password.
//
// This is not documented in the PKWare Appnote.txt.
// This was discovered this by analysis of the Crypt.c source file in the InfoZip library
// http://www.info-zip.org/pub/infozip/
if ((_BitField & 0x0008) != 0x0008)
{
throw new BadPasswordException("The password did not match.");
}
else if (DecryptedHeader[11] != (byte)((_TimeBlob >> 8) & 0xff))
{
throw new BadPasswordException("The password did not match.");
}
}
// We have a good password.
}
return cipher;
}
private void _EmitOne(System.IO.Stream outstream, out ZipCrypto cipher)
{
// If PKZip (weak) encryption is in use, then the entry data is preceded by
// 12-byte "encryption header" for the entry.
byte[] encryptionHeader = null;
cipher = null;
if (_Password != null && Encryption == EncryptionAlgorithm.PkzipWeak)
{
cipher = new ZipCrypto();
// apply the password to the keys
cipher.InitCipher(_Password);
// generate the random 12-byte header:
var rnd = new System.Random();
encryptionHeader = new byte[12];
rnd.NextBytes(encryptionHeader);
// Here, it is important to encrypt the random header, INCLUDING the final byte
// which is the high-order byte of the CRC32. We must do this before
// we encrypt the file data. This step changes the state of the cipher, or in the
// words of the PKZIP spec, it "further initializes" the cipher keys.
// No way around this: must read the stream to compute the actual CRC
FigureCrc32();
encryptionHeader[11] = (byte)((this._Crc32 >> 24) & 0xff);
byte[] cipherText = cipher.EncryptMessage(encryptionHeader, encryptionHeader.Length);
// Write the ciphered bonafide encryption header.
outstream.Write(cipherText, 0, cipherText.Length);
}
// write the (potentially compressed, potentially encrypted) file data
_WriteFileData(cipher, outstream);
_TotalEntrySize = _LengthOfHeader + _CompressedSize;
}
/// <summary>
/// The constructor.
/// </summary>
/// <param name="s">The underlying stream</param>
/// <param name="mode">To either encrypt or decrypt.</param>
/// <param name="cipher">The pre-initialized ZipCrypto object.</param>
public ZipCipherStream(System.IO.Stream s, ZipCrypto cipher, CryptoMode mode)
: base()
{
_cipher = cipher;
_s = s;
_mode = mode;
}
