/* trees.c -- output deflated data using Huffman coding * Copyright (C) 1995-2017 Jean-loup Gailly * detect_data_type() function provided freely by Cosmin Truta, 2006 * For conditions of distribution and use, see copyright notice in zlib.h */ /* * ALGORITHM * * The "deflation" process uses several Huffman trees. The more * common source values are represented by shorter bit sequences. * * Each code tree is stored in a compressed form which is itself * a Huffman encoding of the lengths of all the code strings (in * ascending order by source values). The actual code strings are * reconstructed from the lengths in the inflate process, as described * in the deflate specification. * * REFERENCES * * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification". * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc * * Storer, James A. * Data Compression: Methods and Theory, pp. 49-50. * Computer Science Press, 1988. ISBN 0-7167-8156-5. * * Sedgewick, R. * Algorithms, p290. * Addison-Wesley, 1983. ISBN 0-201-06672-6. */ /* @(#) $Id$ */ /* #define GEN_TREES_H */ #include "deflate.h" #ifdef ZLIB_DEBUG # include #endif /* =========================================================================== * Constants */ #define MAX_BL_BITS 7 /* Bit length codes must not exceed MAX_BL_BITS bits */ #define END_BLOCK 256 /* end of block literal code */ #define REP_3_6 16 /* repeat previous bit length 3-6 times (2 bits of repeat count) */ #define REPZ_3_10 17 /* repeat a zero length 3-10 times (3 bits of repeat count) */ #define REPZ_11_138 18 /* repeat a zero length 11-138 times (7 bits of repeat count) */ local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */ = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0}; local const int extra_dbits[D_CODES] /* extra bits for each distance code */ = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13}; local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */ = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; local const uch bl_order[BL_CODES] = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; /* The lengths of the bit length codes are sent in order of decreasing * probability, to avoid transmitting the lengths for unused bit length codes. */ /* =========================================================================== * Local data. These are initialized only once. */ #define DIST_CODE_LEN 512 /* see definition of array dist_code below */ #if defined(GEN_TREES_H) || !defined(STDC) /* non ANSI compilers may not accept trees.h */ local ct_data static_ltree[L_CODES+2]; /* The static literal tree. Since the bit lengths are imposed, there is no * need for the L_CODES extra codes used during heap construction. However * The codes 286 and 287 are needed to build a canonical tree (see _tr_init * below). */ local ct_data static_dtree[D_CODES]; /* The static distance tree. (Actually a trivial tree since all codes use * 5 bits.) */ uch _dist_code[DIST_CODE_LEN]; /* Distance codes. The first 256 values correspond to the distances * 3 .. 258, the last 256 values correspond to the top 8 bits of * the 15 bit distances. */ uch _length_code[MAX_MATCH-MIN_MATCH+1]; /* length code for each normalized match length (0 == MIN_MATCH) */ local int base_length[LENGTH_CODES]; /* First normalized length for each code (0 = MIN_MATCH) */ local int base_dist[D_CODES]; /* First normalized distance for each code (0 = distance of 1) */ #else # include "trees.h" #endif /* GEN_TREES_H */ struct static_tree_desc_s { const ct_data *static_tree; /* static tree or NULL */ const intf *extra_bits; /* extra bits for each code or NULL */ int extra_base; /* base index for extra_bits */ int elems; /* max number of elements in the tree */ int max_length; /* max bit length for the codes */ }; local const static_tree_desc static_l_desc = {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS}; local const static_tree_desc static_d_desc = {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS}; local const static_tree_desc static_bl_desc = {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS}; /* =========================================================================== * Local (static) routines in this file. */ local void tr_static_init OF((void)); local void init_block OF((deflate_state *s)); local void pqdownheap OF((deflate_state *s, ct_data *tree, int k)); local void gen_bitlen OF((deflate_state *s, tree_desc *desc)); local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count)); local void build_tree OF((deflate_state *s, tree_desc *desc)); local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code)); local void send_tree OF((deflate_state *s, ct_data *tree, int max_code)); local int build_bl_tree OF((deflate_state *s)); local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes, int blcodes)); local void compress_block OF((deflate_state *s, const ct_data *ltree, const ct_data *dtree)); local int detect_data_type OF((deflate_state *s)); local unsigned bi_reverse OF((unsigned value, int length)); local void bi_windup OF((deflate_state *s)); local void bi_flush OF((deflate_state *s)); #ifdef GEN_TREES_H local void gen_trees_header OF((void)); #endif #ifndef ZLIB_DEBUG # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len) /* Send a code of the given tree. c and tree must not have side effects */ #else /* !ZLIB_DEBUG */ # define send_code(s, c, tree) \ { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \ send_bits(s, tree[c].Code, tree[c].Len); } #endif /* =========================================================================== * Output a short LSB first on the stream. * IN assertion: there is enough room in pendingBuf. */ #define put_short(s, w) { \ put_byte(s, (uch)((w) & 0xff)); \ put_byte(s, (uch)((ush)(w) >> 8)); \ } /* =========================================================================== * Send a value on a given number of bits. * IN assertion: length <= 16 and value fits in length bits. */ #ifdef ZLIB_DEBUG local void send_bits OF((deflate_state *s, int value, int length)); local void send_bits(s, value, length) deflate_state *s; int value; /* value to send */ int length; /* number of bits */ { Tracevv((stderr," l %2d v %4x ", length, value)); Assert(length > 0 && length <= 15, "invalid length"); s->bits_sent += (ulg)length; /* If not enough room in bi_buf, use (valid) bits from bi_buf and * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid)) 
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<h1>Security Model</h1>
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<h4>Note to security researchers: If you intend to report a security issue or publish an attack on VeraCrypt, please make sure it does not disregard the security model of VeraCrypt described below. If it does, the attack (or security issue report) will be considered
 invalid/bogus.</h4>
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<p>VeraCrypt is a computer software program whose primary purposes are to:</p>
<ul>
<li>Secure data by encrypting it before it is written to a disk. </li><li>Decrypt encrypted data after it is read from the disk. </li></ul>
<p>VeraCrypt does <strong>not</strong>:</p>
<ul>
<li>Encrypt or secure any portion of RAM (the main memory of a computer). </li><li>Secure any data on a computer* if an attacker has administrator privileges&dagger; under an operating system installed on the computer.
</li><li>Secure any data on a computer if the computer contains any malware (e.g. a virus, Trojan horse, spyware) or any other piece of software (including VeraCrypt or an operating system component) that has been altered, created, or can be controlled, by an attacker.
</li><li>Secure any data on a computer if an attacker has physical access to the computer before or while VeraCrypt is running on it.
</li><li>Secure any data on a computer if an attacker has physical access to the computer between the time when VeraCrypt is shut down and the time when the entire contents of all volatile memory modules connected to the computer (including memory modules in peripheral
 devices) have been permanently and irreversibly erased/lost. </li><li>Secure any data on a computer if an attacker can remotely intercept emanations from the computer hardware (e.g. the monitor or cables) while VeraCrypt is running on it (or otherwise remotely monitor the hardware and its use, directly or indirectly, while
 VeraCrypt is running on it). </li><li>Secure any data stored in a VeraCrypt volume&Dagger; if an attacker without administrator privileges can access the contents of the mounted volume (e.g. if file/folder/volume permissions do not prevent such an attacker from accessing it).
</li><li>Preserve/verify the integrity or authenticity of encrypted or decrypted data.
</li><li>Prevent traffic analysis when encrypted data is transmitted over a network. </li><li>Prevent an attacker from determining in which sectors of the volume the content changed (and when and how many times) if he or she can observe the volume (dismounted or mounted) before and after data is written to it, or if the storage medium/device allows
 the attacker to determine such information (for example, the volume resides on a device that saves metadata that can be used to determine when data was written to a particular sector).
</li><li>Encrypt any existing unencrypted data in place (or re-encrypt or erase data) on devices/filesystems that use wear-leveling or otherwise relocate data internally.
</li><li>Ensure that users choose cryptographically strong passwords or keyfiles. </li><li>Secure any computer hardware component or a whole computer. </li><li>Secure any data on a computer where the security requirements or precautions listed in the chapter
<a href="Security%20Requirements%20and%20Precautions.html">
<em>Security Requirements and Precautions</em></a> are not followed. </li><li>Do anything listed in the section <a href="Issues%20and%20Limitations.html#limitations">
Limitations </a>(chapter <a href="Issues%20and%20Limitations.html">
Known Issues &amp; Limitations</a>). </li></ul>
<p>Under <strong>Windows</strong>, a user without administrator privileges can (assuming the default VeraCrypt and operating system configurations):</p>
<ul>
<li>Mount any file-hosted VeraCrypt volume provided that the file permissions of the container allow it.
</li><li>Mount any partition/device-hosted VeraCrypt volume. </li><li>Complete the pre-boot authentication process and, thus, gain access to data on an encrypted system partition/drive (and start the encrypted operating system).
</li><li>Skip the pre-boot authentication process (this can be prevented by disabling the option
<em>Settings</em> &gt; &lsquo;<em>System Encryption</em>&rsquo; &gt; &lsquo;<em>Allow pre-boot authentication to be bypassed by pressing the Esc key</em>&rsquo;; note that this option can be enabled or disabled only by an administrator).
</li><li>Dismount, using VeraCrypt, (and, in the VeraCrypt application window, see the path to and properties of) any VeraCrypt volume mounted by him or her. However, this does not apply to &lsquo;system favorite volumes&rsquo;, which he or she can dismount (etc.)
 regardless of who mounted them (this can be prevented by enabling the option <em>
Settings</em> &gt; &lsquo;<em>System Favorite Volumes</em>&rsquo; &gt; &lsquo;<em>Allow</em> only administrators to view and dismount system favorite volumes in VeraCrypt&rsquo;; note that this option can be enabled or disabled only by an administrator).
</li><li>Create a file-hosted VeraCrypt volume containing a FAT or no file system (provided that the relevant folder permissions allow it).
</li><li>Change the password, keyfiles, and header key derivation algorithm for, and restore or back up the header of, a file-hosted VeraCrypt volume (provided that the file permissions allow it).
</li><li>Access the filesystem residing within a VeraCrypt volume mounted by another user on the system (however, file/folder/volume permissions can be set to prevent this).
</li><li>Use passwords (and processed keyfiles) stored in the password cache (note that caching can be disabled; for more information see the section
<em>Settings -&gt; Preferences</em>, subsection <em>Cache passwords in</em> driver memory).
</li><li>View the basic properties (e.g. the size of the encrypted area, encryption and hash algorithms used, etc.) of the encrypted system partition/drive when the encrypted system is running.
</li><li>Run and use the VeraCrypt application (including the VeraCrypt Volume Creation Wizard) provided that the VeraCrypt device driver is running and that the file permissions allow it.
</li></ul>
<p>Under <strong>Linux</strong>, a user without administrator privileges can (assuming the default VeraCrypt and operating system configurations):</p>
<ul>
<li>Create a file-hosted or partition/device-hosted VeraCrypt volume containing a FAT or no file system provided that the relevant folder/device permissions allow it.
</li><li>Change the password, keyfiles, and header key derivation algorithm for, and restore or back up the header of, a file-hosted or partition/device-hosted VeraCrypt volume provided that the file/device permissions allow it.
</li><li>Access the filesystem residing within a VeraCrypt volume mounted by another user on the system (however, file/folder/volume permissions can be set to prevent this).
</li><li>Run and use the VeraCrypt application (including the VeraCrypt Volume Creation Wizard) provided that file permissions allow it.
</li><li>In the VeraCrypt application window, see the path to and properties of any VeraCrypt volume mounted by him or her.
</li></ul>
<p>Under <strong>Mac OS X</strong>, a user without administrator privileges can (assuming the default VeraCrypt and operating system configurations):</p>
<ul>
<li>Mount any file-hosted or partition/device-hosted VeraCrypt volume provided that the file/device permissions allow it.
</li><li>Dismount, using VeraCrypt, (and, in the VeraCrypt application window, see the path to and properties of) any VeraCrypt volume mounted by him or her.
</li><li>Create a file-hosted or partition/device-hosted VeraCrypt volume provided that the relevant folder/device permissions allow it.
</li><li>Change the password, keyfiles, and header key derivation algorithm for, and restore or back up the header of, a file-hosted or partition/device-hosted VeraCrypt volume (provided that the file/device permissions allow it).
</li><li>Access the filesystem residing within a VeraCrypt volume mounted by another user on the system (however, file/folder/volume permissions can be set to prevent this).
</li><li>Run and use the VeraCrypt application (including the VeraCrypt Volume Creation Wizard) provided that the file permissions allow it.
</li></ul>
<p>VeraCrypt does not support the set-euid root mode of execution.<br>
<br>
Additional information and details regarding the security model are contained in the chapter
<a href="Security%20Requirements%20and%20Precautions.html">
<em>Security Requirements and Precautions</em></a>.</p>
<p>* In this section (<em>Security Model</em>), the phrase &ldquo;data on a computer&rdquo; means data on internal and external storage devices/media (including removable devices and network drives) connected to the computer.</p>
<p>&dagger; In this section (<em>Security Model</em>), the phrase &ldquo;administrator privileges&rdquo; does not necessarily refer to a valid administrator account. It may also refer to an attacker who does not have a valid administrator account but who is
 able (for example, due to improper configuration of the system or by exploiting a vulnerability in the operating system or a third-party application) to perform any action that only a user with a valid administrator account is normally allowed to perform (for
 example, to read or modify an arbitrary part of a drive or the RAM, etc.)</p>
<p>&Dagger; &ldquo;VeraCrypt volume&rdquo; also means a VeraCrypt-encrypted system partition/drive (see the chapter
<a href="System%20Encryption.html"><em>System Encryption</em></a>).</p>
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n-textual ("black-listed") bytes. */ for (n = 0; n <= 31; n++, black_mask >>= 1) if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0)) return Z_BINARY; /* Check for textual ("white-listed") bytes. */ if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0 || s->dyn_ltree[13].Freq != 0) return Z_TEXT; for (n = 32; n < LITERALS; n++) if (s->dyn_ltree[n].Freq != 0) return Z_TEXT; /* There are no "black-listed" or "white-listed" bytes: * this stream either is empty or has tolerated ("gray-listed") bytes only. */ return Z_BINARY; } /* =========================================================================== * Reverse the first len bits of a code, using straightforward code (a faster * method would use a table) * IN assertion: 1 <= len <= 15 */ local unsigned bi_reverse(code, len) unsigned code; /* the value to invert */ int len; /* its bit length */ { register unsigned res = 0; do { res |= code & 1; code >>= 1, res <<= 1; } while (--len > 0); return res >> 1; } /* =========================================================================== * Flush the bit buffer, keeping at most 7 bits in it. */ local void bi_flush(s) deflate_state *s; { if (s->bi_valid == 16) { put_short(s, s->bi_buf); s->bi_buf = 0; s->bi_valid = 0; } else if (s->bi_valid >= 8) { put_byte(s, (Byte)s->bi_buf); s->bi_buf >>= 8; s->bi_valid -= 8; } } /* =========================================================================== * Flush the bit buffer and align the output on a byte boundary */ local void bi_windup(s) deflate_state *s; { if (s->bi_valid > 8) { put_short(s, s->bi_buf); } else if (s->bi_valid > 0) { put_byte(s, (Byte)s->bi_buf); } s->bi_buf = 0; s->bi_valid = 0; #ifdef ZLIB_DEBUG s->bits_sent = (s->bits_sent+7) & ~7; #endif }