kopia lustrzana https://github.com/dl2alf/AirScout
456 wiersze
16 KiB
C#
456 wiersze
16 KiB
C#
// ZipCrypto.cs
|
|
// ------------------------------------------------------------------
|
|
//
|
|
// Copyright (c) 2008, 2009, 2011 Dino Chiesa
|
|
// All rights reserved.
|
|
//
|
|
// This code module is part of DotNetZip, a zipfile class library.
|
|
//
|
|
// ------------------------------------------------------------------
|
|
//
|
|
// This code is licensed under the Microsoft Public License.
|
|
// See the file License.txt for the license details.
|
|
// More info on: http://dotnetzip.codeplex.com
|
|
//
|
|
// ------------------------------------------------------------------
|
|
//
|
|
// last saved (in emacs):
|
|
// Time-stamp: <2011-July-28 06:30:59>
|
|
//
|
|
// ------------------------------------------------------------------
|
|
//
|
|
// This module provides the implementation for "traditional" Zip encryption.
|
|
//
|
|
// Created Tue Apr 15 17:39:56 2008
|
|
//
|
|
// ------------------------------------------------------------------
|
|
|
|
using System;
|
|
|
|
namespace Ionic.Zip
|
|
{
|
|
/// <summary>
|
|
/// This class implements the "traditional" or "classic" PKZip encryption,
|
|
/// which today is considered to be weak. On the other hand it is
|
|
/// ubiquitous. This class is intended for use only by the DotNetZip
|
|
/// library.
|
|
/// </summary>
|
|
///
|
|
/// <remarks>
|
|
/// Most uses of the DotNetZip library will not involve direct calls into
|
|
/// the ZipCrypto class. Instead, the ZipCrypto class is instantiated and
|
|
/// used by the ZipEntry() class when encryption or decryption on an entry
|
|
/// is employed. If for some reason you really wanted to use a weak
|
|
/// encryption algorithm in some other application, you might use this
|
|
/// library. But you would be much better off using one of the built-in
|
|
/// strong encryption libraries in the .NET Framework, like the AES
|
|
/// algorithm or SHA.
|
|
/// </remarks>
|
|
internal class ZipCrypto
|
|
{
|
|
/// <summary>
|
|
/// The default constructor for ZipCrypto.
|
|
/// </summary>
|
|
///
|
|
/// <remarks>
|
|
/// This class is intended for internal use by the library only. It's
|
|
/// probably not useful to you. Seriously. Stop reading this
|
|
/// documentation. It's a waste of your time. Go do something else.
|
|
/// Check the football scores. Go get an ice cream with a friend.
|
|
/// Seriously.
|
|
/// </remarks>
|
|
///
|
|
private ZipCrypto() { }
|
|
|
|
public static ZipCrypto ForWrite(string password)
|
|
{
|
|
ZipCrypto z = new ZipCrypto();
|
|
if (password == null)
|
|
throw new BadPasswordException("This entry requires a password.");
|
|
z.InitCipher(password);
|
|
return z;
|
|
}
|
|
|
|
|
|
public static ZipCrypto ForRead(string password, ZipEntry e)
|
|
{
|
|
System.IO.Stream s = e._archiveStream;
|
|
e._WeakEncryptionHeader = new byte[12];
|
|
byte[] eh = e._WeakEncryptionHeader;
|
|
ZipCrypto z = new ZipCrypto();
|
|
|
|
if (password == null)
|
|
throw new BadPasswordException("This entry requires a password.");
|
|
|
|
z.InitCipher(password);
|
|
|
|
ZipEntry.ReadWeakEncryptionHeader(s, eh);
|
|
|
|
// Decrypt the header. This has a side effect of "further initializing the
|
|
// encryption keys" in the traditional zip encryption.
|
|
byte[] DecryptedHeader = z.DecryptMessage(eh, eh.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)((e._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' or a 'data
|
|
// descriptor' (signature 0x08074b50), the last byte of the decrypted
|
|
// header is sometimes compared with the high-order byte of the
|
|
// lastmodified time, rather than the high-order byte of the CRC, to
|
|
// verify the password.
|
|
//
|
|
// This is not documented in the PKWare Appnote.txt. It was
|
|
// discovered this by analysis of the Crypt.c source file in the
|
|
// InfoZip library http://www.info-zip.org/pub/infozip/
|
|
//
|
|
// The reason for this is that the CRC for a file cannot be known
|
|
// until the entire contents of the file have been streamed. This
|
|
// means a tool would have to read the file content TWICE in its
|
|
// entirety in order to perform PKZIP encryption - once to compute
|
|
// the CRC, and again to actually encrypt.
|
|
//
|
|
// This is so important for performance that using the timeblob as
|
|
// the verification should be the standard practice for DotNetZip
|
|
// when using PKZIP encryption. This implies that bit 3 must be
|
|
// set. The downside is that some tools still cannot cope with ZIP
|
|
// files that use bit 3. Therefore, DotNetZip DOES NOT force bit 3
|
|
// when PKZIP encryption is in use, and instead, reads the stream
|
|
// twice.
|
|
//
|
|
|
|
if ((e._BitField & 0x0008) != 0x0008)
|
|
{
|
|
throw new BadPasswordException("The password did not match.");
|
|
}
|
|
else if (DecryptedHeader[11] != (byte)((e._TimeBlob >> 8) & 0xff))
|
|
{
|
|
throw new BadPasswordException("The password did not match.");
|
|
}
|
|
|
|
// We have a good password.
|
|
}
|
|
else
|
|
{
|
|
// A-OK
|
|
}
|
|
return z;
|
|
}
|
|
|
|
|
|
|
|
|
|
/// <summary>
|
|
/// From AppNote.txt:
|
|
/// unsigned char decrypt_byte()
|
|
/// local unsigned short temp
|
|
/// temp :=- Key(2) | 2
|
|
/// decrypt_byte := (temp * (temp ^ 1)) bitshift-right 8
|
|
/// end decrypt_byte
|
|
/// </summary>
|
|
private byte MagicByte
|
|
{
|
|
get
|
|
{
|
|
UInt16 t = (UInt16)((UInt16)(_Keys[2] & 0xFFFF) | 2);
|
|
return (byte)((t * (t ^ 1)) >> 8);
|
|
}
|
|
}
|
|
|
|
// Decrypting:
|
|
// From AppNote.txt:
|
|
// loop for i from 0 to 11
|
|
// C := buffer(i) ^ decrypt_byte()
|
|
// update_keys(C)
|
|
// buffer(i) := C
|
|
// end loop
|
|
|
|
|
|
/// <summary>
|
|
/// Call this method on a cipher text to render the plaintext. You must
|
|
/// first initialize the cipher with a call to InitCipher.
|
|
/// </summary>
|
|
///
|
|
/// <example>
|
|
/// <code>
|
|
/// var 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[] DecryptedMessage = cipher.DecryptMessage(EncryptedMessage);
|
|
/// </code>
|
|
/// </example>
|
|
///
|
|
/// <param name="cipherText">The encrypted buffer.</param>
|
|
/// <param name="length">
|
|
/// The number of bytes to encrypt.
|
|
/// Should be less than or equal to CipherText.Length.
|
|
/// </param>
|
|
///
|
|
/// <returns>The plaintext.</returns>
|
|
public byte[] DecryptMessage(byte[] cipherText, int length)
|
|
{
|
|
if (cipherText == null)
|
|
throw new ArgumentNullException("cipherText");
|
|
|
|
if (length > cipherText.Length)
|
|
throw new ArgumentOutOfRangeException("length",
|
|
"Bad length during Decryption: the length parameter must be smaller than or equal to the size of the destination array.");
|
|
|
|
byte[] plainText = new byte[length];
|
|
for (int i = 0; i < length; i++)
|
|
{
|
|
byte C = (byte)(cipherText[i] ^ MagicByte);
|
|
UpdateKeys(C);
|
|
plainText[i] = C;
|
|
}
|
|
return plainText;
|
|
}
|
|
|
|
/// <summary>
|
|
/// This is the converse of DecryptMessage. It encrypts the plaintext
|
|
/// and produces a ciphertext.
|
|
/// </summary>
|
|
///
|
|
/// <param name="plainText">The plain text buffer.</param>
|
|
///
|
|
/// <param name="length">
|
|
/// The number of bytes to encrypt.
|
|
/// Should be less than or equal to plainText.Length.
|
|
/// </param>
|
|
///
|
|
/// <returns>The ciphertext.</returns>
|
|
public byte[] EncryptMessage(byte[] plainText, int length)
|
|
{
|
|
if (plainText == null)
|
|
throw new ArgumentNullException("plaintext");
|
|
|
|
if (length > plainText.Length)
|
|
throw new ArgumentOutOfRangeException("length",
|
|
"Bad length during Encryption: The length parameter must be smaller than or equal to the size of the destination array.");
|
|
|
|
byte[] cipherText = new byte[length];
|
|
for (int i = 0; i < length; i++)
|
|
{
|
|
byte C = plainText[i];
|
|
cipherText[i] = (byte)(plainText[i] ^ MagicByte);
|
|
UpdateKeys(C);
|
|
}
|
|
return cipherText;
|
|
}
|
|
|
|
|
|
/// <summary>
|
|
/// This initializes the cipher with the given password.
|
|
/// See AppNote.txt for details.
|
|
/// </summary>
|
|
///
|
|
/// <param name="passphrase">
|
|
/// The passphrase for encrypting or decrypting with this cipher.
|
|
/// </param>
|
|
///
|
|
/// <remarks>
|
|
/// <code>
|
|
/// Step 1 - Initializing the encryption keys
|
|
/// -----------------------------------------
|
|
/// Start with these keys:
|
|
/// Key(0) := 305419896 (0x12345678)
|
|
/// Key(1) := 591751049 (0x23456789)
|
|
/// Key(2) := 878082192 (0x34567890)
|
|
///
|
|
/// Then, initialize the keys with a password:
|
|
///
|
|
/// loop for i from 0 to length(password)-1
|
|
/// update_keys(password(i))
|
|
/// end loop
|
|
///
|
|
/// Where update_keys() is defined as:
|
|
///
|
|
/// update_keys(char):
|
|
/// Key(0) := crc32(key(0),char)
|
|
/// Key(1) := Key(1) + (Key(0) bitwiseAND 000000ffH)
|
|
/// Key(1) := Key(1) * 134775813 + 1
|
|
/// Key(2) := crc32(key(2),key(1) rightshift 24)
|
|
/// end update_keys
|
|
///
|
|
/// Where crc32(old_crc,char) is a routine that given a CRC value and a
|
|
/// character, returns an updated CRC value after applying the CRC-32
|
|
/// algorithm described elsewhere in this document.
|
|
///
|
|
/// </code>
|
|
///
|
|
/// <para>
|
|
/// After the keys are initialized, then you can use the cipher to
|
|
/// encrypt the plaintext.
|
|
/// </para>
|
|
///
|
|
/// <para>
|
|
/// Essentially we encrypt the password with the keys, then discard the
|
|
/// ciphertext for the password. This initializes the keys for later use.
|
|
/// </para>
|
|
///
|
|
/// </remarks>
|
|
public void InitCipher(string passphrase)
|
|
{
|
|
byte[] p = SharedUtilities.StringToByteArray(passphrase);
|
|
for (int i = 0; i < passphrase.Length; i++)
|
|
UpdateKeys(p[i]);
|
|
}
|
|
|
|
|
|
private void UpdateKeys(byte byteValue)
|
|
{
|
|
_Keys[0] = (UInt32)crc32.ComputeCrc32((int)_Keys[0], byteValue);
|
|
_Keys[1] = _Keys[1] + (byte)_Keys[0];
|
|
_Keys[1] = _Keys[1] * 0x08088405 + 1;
|
|
_Keys[2] = (UInt32)crc32.ComputeCrc32((int)_Keys[2], (byte)(_Keys[1] >> 24));
|
|
}
|
|
|
|
///// <summary>
|
|
///// The byte array representing the seed keys used.
|
|
///// Get this after calling InitCipher. The 12 bytes represents
|
|
///// what the zip spec calls the "EncryptionHeader".
|
|
///// </summary>
|
|
//public byte[] KeyHeader
|
|
//{
|
|
// get
|
|
// {
|
|
// byte[] result = new byte[12];
|
|
// result[0] = (byte)(_Keys[0] & 0xff);
|
|
// result[1] = (byte)((_Keys[0] >> 8) & 0xff);
|
|
// result[2] = (byte)((_Keys[0] >> 16) & 0xff);
|
|
// result[3] = (byte)((_Keys[0] >> 24) & 0xff);
|
|
// result[4] = (byte)(_Keys[1] & 0xff);
|
|
// result[5] = (byte)((_Keys[1] >> 8) & 0xff);
|
|
// result[6] = (byte)((_Keys[1] >> 16) & 0xff);
|
|
// result[7] = (byte)((_Keys[1] >> 24) & 0xff);
|
|
// result[8] = (byte)(_Keys[2] & 0xff);
|
|
// result[9] = (byte)((_Keys[2] >> 8) & 0xff);
|
|
// result[10] = (byte)((_Keys[2] >> 16) & 0xff);
|
|
// result[11] = (byte)((_Keys[2] >> 24) & 0xff);
|
|
// return result;
|
|
// }
|
|
//}
|
|
|
|
// private fields for the crypto stuff:
|
|
private UInt32[] _Keys = { 0x12345678, 0x23456789, 0x34567890 };
|
|
private Ionic.Crc.CRC32 crc32 = new Ionic.Crc.CRC32();
|
|
|
|
}
|
|
|
|
internal enum CryptoMode
|
|
{
|
|
Encrypt,
|
|
Decrypt
|
|
}
|
|
|
|
/// <summary>
|
|
/// A Stream for reading and concurrently decrypting data from a zip file,
|
|
/// or for writing and concurrently encrypting data to a zip file.
|
|
/// </summary>
|
|
internal class ZipCipherStream : System.IO.Stream
|
|
{
|
|
private ZipCrypto _cipher;
|
|
private System.IO.Stream _s;
|
|
private CryptoMode _mode;
|
|
|
|
/// <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;
|
|
}
|
|
|
|
public override int Read(byte[] buffer, int offset, int count)
|
|
{
|
|
if (_mode == CryptoMode.Encrypt)
|
|
throw new NotSupportedException("This stream does not encrypt via Read()");
|
|
|
|
if (buffer == null)
|
|
throw new ArgumentNullException("buffer");
|
|
|
|
byte[] db = new byte[count];
|
|
int n = _s.Read(db, 0, count);
|
|
byte[] decrypted = _cipher.DecryptMessage(db, n);
|
|
for (int i = 0; i < n; i++)
|
|
{
|
|
buffer[offset + i] = decrypted[i];
|
|
}
|
|
return n;
|
|
}
|
|
|
|
public override void Write(byte[] buffer, int offset, int count)
|
|
{
|
|
if (_mode == CryptoMode.Decrypt)
|
|
throw new NotSupportedException("This stream does not Decrypt via Write()");
|
|
|
|
if (buffer == null)
|
|
throw new ArgumentNullException("buffer");
|
|
|
|
// workitem 7696
|
|
if (count == 0) return;
|
|
|
|
byte[] plaintext = null;
|
|
if (offset != 0)
|
|
{
|
|
plaintext = new byte[count];
|
|
for (int i = 0; i < count; i++)
|
|
{
|
|
plaintext[i] = buffer[offset + i];
|
|
}
|
|
}
|
|
else plaintext = buffer;
|
|
|
|
byte[] encrypted = _cipher.EncryptMessage(plaintext, count);
|
|
_s.Write(encrypted, 0, encrypted.Length);
|
|
}
|
|
|
|
|
|
public override bool CanRead
|
|
{
|
|
get { return (_mode == CryptoMode.Decrypt); }
|
|
}
|
|
public override bool CanSeek
|
|
{
|
|
get { return false; }
|
|
}
|
|
|
|
public override bool CanWrite
|
|
{
|
|
get { return (_mode == CryptoMode.Encrypt); }
|
|
}
|
|
|
|
public override void Flush()
|
|
{
|
|
//throw new NotSupportedException();
|
|
}
|
|
|
|
public override long Length
|
|
{
|
|
get { throw new NotSupportedException(); }
|
|
}
|
|
|
|
public override long Position
|
|
{
|
|
get { throw new NotSupportedException(); }
|
|
set { throw new NotSupportedException(); }
|
|
}
|
|
public override long Seek(long offset, System.IO.SeekOrigin origin)
|
|
{
|
|
throw new NotSupportedException();
|
|
}
|
|
|
|
public override void SetLength(long value)
|
|
{
|
|
throw new NotSupportedException();
|
|
}
|
|
}
|
|
}
|