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43 <P><B>7z</B> is the new archive format, providing high compression ratio.</P>
45 <P>The main features of <B>7z</B> format:</P>
48 <LI>High compression ratio
49 <LI>Strong AES-256 encryption
50 <LI>Ability of using any compression, conversion or encryption method
51 <LI>Supporting files with sizes up to 16000000000 GB
52 <LI>Unicode file names
54 <LI>Archive headers compressing
57 <P><B>7z</B> has open architecture, so it can support any new compression methods.
58 Now the following methods are integrated to <B>7z</B>:</P>
60 <TABLE cellspacing ="2" cellpadding ="4">
61 <TR> <TH class="Title" width="60">Method</TH> <TH class="Title">Description</TH></TR>
62 <TR> <TD class="Item">LZMA</TD> <TD class="Item">Improved and optimized version of LZ77 algorithm</TD></TR>
63 <TR> <TD class="Item">PPMD</TD> <TD class="Item">Dmitry Shkarin's PPMdH with small changes</TD></TR>
64 <TR> <TD class="Item">BCJ</TD> <TD class="Item">Converter for 32-bit x86 executables</TD></TR>
65 <TR> <TD class="Item">BCJ2</TD> <TD class="Item">Converter for 32-bit x86 executables</TD></TR>
66 <TR> <TD class="Item">BZip2</TD> <TD class="Item">Standard BWT algorithm</TD></TR>
67 <TR> <TD class="Item">Deflate</TD> <TD class="Item">Standard LZ77-based algorithm</TD></TR>
70 <P><B>LZMA</B> is default and general compression method of <B>7z</B> format. The main features of <B>LZMA</B> method:</P>
72 <LI>High compression ratio
73 <LI>Variable dictionary size (up to 4 GB)
74 <LI>Compressing speed: about 1 MB/s on 2 GHz CPU
75 <LI>Decompressing speed: about 10-20 MB/s on 2 GHz CPU
76 <LI>Small memory requirements for decompressing (depend from dictionary size)
77 <LI>Small code size for decompressing: about 5 KB
78 <LI>Supporting multi-threading and P4's hyper-threading
81 <P><B>LZMA</B> compression algorithm is very suitable for embedded applications.
82 <B>LZMA</B> is released under the terms of the GNU LGPL. <B>LZMA</B> is also
83 available under a proprietary license for those who can not use the GNU LGPL in
84 their code. If you want to use <B>LZMA</B> code, you can ask consultations,
85 custom code programming and required developer licenses
86 from page for support:
87 <A href="support.html">Send message to LZMA developer</A>.
88 Check also information about <A href ="sdk.html">LZMA SDK</A>.</P>
90 <P>7-Zip also supports encryption with AES-256 algorithm.
91 This algorithm uses cipher key with length of 256 bits. To create that key 7-Zip
92 uses derivation function based on SHA-256 hash algorithm.
93 A key derivation function produces a derived key from text password defined by user.
94 For increasing the cost of exhaustive search for passwords 7-Zip uses big number
95 of iterations to produce cipher key from text password.</P>
97 <P><B>7z</B> is a part of <A href="./">7-Zip</A> program distributed under the GNU LGPL.
98 You can download <B>7-Zip</B> sources and binaries from <A href ="download.html">Download Page</A>.</P>
100 <p>Applications that support <B>7z</B> archives: WinRAR, PowerArchiver, TUGZip, IZArc.</p>
104 <li><A href="http://en.wikipedia.org/wiki/7z">7z at Wikipedia</A></li>
107 <HR><P><SMALL>Copyright (C) 2008 Igor Pavlov.</SMALL></P>
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