// For AES the method in the entry is 99, and the real compression method is in the extradata
//
private void ProcessAESExtraData(ZipExtraData extraData)
{
if (extraData.Find(0x9901))
{
// Set version and flag for Zipfile.CreateAndInitDecryptionStream
this.versionToExtract = ZipConstants.VERSION_AES; // Ver 5.1 = AES see "Version" getter
// Set StrongEncryption flag for ZipFile.CreateAndInitDecryptionStream
this.Flags = this.Flags | (int)GeneralBitFlags.StrongEncryption;
//
// Unpack AES extra data field see http://www.winzip.com/aes_info.htm
int length = extraData.ValueLength; // Data size currently 7
if (length < 7)
{
throw new ZipException("AES Extra Data Length " + length + " invalid.");
}
int ver = extraData.ReadShort(); // Version number (1=AE-1 2=AE-2)
int vendorId = extraData.ReadShort(); // 2-character vendor ID 0x4541 = "AE"
int encrStrength = extraData.ReadByte(); // encryption strength 1 = 128 2 = 192 3 = 256
int actualCompress = extraData.ReadShort(); // The actual compression method used to compress the file
this._aesVer = ver;
this._aesEncryptionStrength = encrStrength;
this.method = (CompressionMethod)actualCompress;
}
else
{
throw new ZipException("AES Extra Data missing");
}
}
// Write the local file header
// TODO: ZipHelperStream.WriteLocalHeader is not yet used and needs checking for ZipFile and ZipOuptutStream usage
private void WriteLocalHeader(ZipEntry entry, EntryPatchData patchData)
{
CompressionMethod method = entry.CompressionMethod;
bool headerInfoAvailable = true; // How to get this?
bool patchEntryHeader = false;
this.WriteLEInt(ZipConstants.LocalHeaderSignature);
this.WriteLEShort(entry.Version);
this.WriteLEShort(entry.Flags);
this.WriteLEShort((byte)method);
this.WriteLEInt((int)entry.DosTime);
if (headerInfoAvailable == true)
{
this.WriteLEInt((int)entry.Crc);
if (entry.LocalHeaderRequiresZip64)
{
this.WriteLEInt(-1);
this.WriteLEInt(-1);
}
else
{
this.WriteLEInt(entry.IsCrypted ? (int)entry.CompressedSize + ZipConstants.CryptoHeaderSize : (int)entry.CompressedSize);
this.WriteLEInt((int)entry.Size);
}
}
else
{
if (patchData != null)
{
patchData.CrcPatchOffset = this.stream_.Position;
}
this.WriteLEInt(0); // Crc
if (patchData != null)
{
patchData.SizePatchOffset = this.stream_.Position;
}
// For local header both sizes appear in Zip64 Extended Information
if (entry.LocalHeaderRequiresZip64 && patchEntryHeader)
{
this.WriteLEInt(-1);
this.WriteLEInt(-1);
}
else
{
this.WriteLEInt(0); // Compressed size
this.WriteLEInt(0); // Uncompressed size
}
}
byte[] name = ZipStrings.ConvertToArray(entry.Flags, entry.Name);
if (name.Length > 0xFFFF)
{
throw new ZipException("Entry name too long.");
}
var ed = new ZipExtraData(entry.ExtraData);
if (entry.LocalHeaderRequiresZip64 && (headerInfoAvailable || patchEntryHeader))
{
ed.StartNewEntry();
if (headerInfoAvailable)
{
ed.AddLeLong(entry.Size);
ed.AddLeLong(entry.CompressedSize);
}
else
{
ed.AddLeLong(-1);
ed.AddLeLong(-1);
}
ed.AddNewEntry(1);
if (!ed.Find(1))
{
throw new ZipException("Internal error cant find extra data");
}
if (patchData != null)
{
patchData.SizePatchOffset = ed.CurrentReadIndex;
}
}
else
{
ed.Delete(1);
}
byte[] extra = ed.GetEntryData();
this.WriteLEShort(name.Length);
this.WriteLEShort(extra.Length);
if (name.Length > 0)
{
this.stream_.Write(name, 0, name.Length);
}
if (entry.LocalHeaderRequiresZip64 && patchEntryHeader)
{
patchData.SizePatchOffset += this.stream_.Position;
}
if (extra.Length > 0)
{
this.stream_.Write(extra, 0, extra.Length);
}
}
/// <summary>
/// Process extra data fields updating the entry based on the contents.
/// </summary>
/// <param name="localHeader">True if the extra data fields should be handled
/// for a local header, rather than for a central header.
/// </param>
internal void ProcessExtraData(bool localHeader)
{
var extraData = new ZipExtraData(this.extra);
if (extraData.Find(0x0001))
{
// Version required to extract is ignored here as some archivers dont set it correctly
// in theory it should be version 45 or higher
// The recorded size will change but remember that this is zip64.
this.forceZip64_ = true;
if (extraData.ValueLength < 4)
{
throw new ZipException("Extra data extended Zip64 information length is invalid");
}
// (localHeader ||) was deleted, because actually there is no specific difference with reading sizes between local header & central directory
// https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT
// ...
// 4.4 Explanation of fields
// ...
// 4.4.8 compressed size: (4 bytes)
// 4.4.9 uncompressed size: (4 bytes)
//
// The size of the file compressed (4.4.8) and uncompressed,
// (4.4.9) respectively. When a decryption header is present it
// will be placed in front of the file data and the value of the
// compressed file size will include the bytes of the decryption
// header. If bit 3 of the general purpose bit flag is set,
// these fields are set to zero in the local header and the
// correct values are put in the data descriptor and
// in the central directory. If an archive is in ZIP64 format
// and the value in this field is 0xFFFFFFFF, the size will be
// in the corresponding 8 byte ZIP64 extended information
// extra field. When encrypting the central directory, if the
// local header is not in ZIP64 format and general purpose bit
// flag 13 is set indicating masking, the value stored for the
// uncompressed size in the Local Header will be zero.
//
// Othewise there is problem with minizip implementation
if (this.size == uint.MaxValue)
{
this.size = (ulong)extraData.ReadLong();
}
if (this.compressedSize == uint.MaxValue)
{
this.compressedSize = (ulong)extraData.ReadLong();
}
if (!localHeader && (this.offset == uint.MaxValue))
{
this.offset = extraData.ReadLong();
}
// Disk number on which file starts is ignored
}
else
{
if (
((this.versionToExtract & 0xff) >= ZipConstants.VersionZip64) &&
((this.size == uint.MaxValue) || (this.compressedSize == uint.MaxValue))
)
{
throw new ZipException("Zip64 Extended information required but is missing.");
}
}
this.DateTime = this.GetDateTime(extraData);
if (this.method == CompressionMethod.WinZipAES)
{
this.ProcessAESExtraData(extraData);
}
}