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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html;charset=UTF-8"><title>Crypto++: arc4.cpp Source File</title><link href="doxygen.css" rel="stylesheet" type="text/css"><link href="tabs.css" rel="stylesheet" type="text/css"></head><body><!-- Generated by Doxygen 1.5.2 --><div class="tabs"> <ul> <li><a href="index.html"><span>Main Page</span></a></li> <li><a href="namespaces.html"><span>Namespaces</span></a></li> <li><a href="classes.html"><span>Classes</span></a></li> <li class="current"><a href="files.html"><span>Files</span></a></li> </ul></div><div class="tabs"> <ul> <li><a href="files.html"><span>File List</span></a></li> <li><a href="globals.html"><span>File Members</span></a></li> </ul></div><h1>arc4.cpp</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">// arc4.cpp - written and placed in the public domain by Wei Dai</span><a name="l00002"></a>00002 <a name="l00003"></a>00003 <span class="comment">// The ARC4 algorithm was first revealed in an anonymous email to the</span><a name="l00004"></a>00004 <span class="comment">// cypherpunks mailing list. This file originally contained some</span><a name="l00005"></a>00005 <span class="comment">// code copied from this email. The code has since been rewritten in order</span><a name="l00006"></a>00006 <span class="comment">// to clarify the copyright status of this file. It should now be</span><a name="l00007"></a>00007 <span class="comment">// completely in the public domain.</span><a name="l00008"></a>00008 <a name="l00009"></a>00009 <span class="preprocessor">#include "pch.h"</span><a name="l00010"></a>00010 <span class="preprocessor">#define CRYPTOPP_ENABLE_NAMESPACE_WEAK 1</span><a name="l00011"></a>00011 <span class="preprocessor"></span><span class="preprocessor">#include "arc4.h"</span><a name="l00012"></a>00012 <a name="l00013"></a>00013 NAMESPACE_BEGIN(CryptoPP)<a name="l00014"></a><a class="code" href="namespace_weak1.html">00014</a> namespace Weak1 {<a name="l00015"></a>00015 <a name="l00016"></a><a class="code" href="namespace_weak1.html#f70e36bad2c7d64ffd90e4ebd5389be5">00016</a> <span class="keywordtype">void</span> <a class="code" href="namespace_weak1.html#f70e36bad2c7d64ffd90e4ebd5389be5">ARC4_TestInstantiations</a>()<a name="l00017"></a>00017 {<a name="l00018"></a>00018 <a class="code" href="class_weak1_1_1_a_r_c4.html" title="Alleged RC4">ARC4</a> x;<a name="l00019"></a>00019 }<a name="l00020"></a>00020 <a name="l00021"></a><a class="code" href="class_weak1_1_1_a_r_c4___base.html#32a4bee98452d1b1b33cd0cabc254254">00021</a> ARC4_Base::~ARC4_Base()<a name="l00022"></a>00022 {<a name="l00023"></a>00023 <a class="code" href="class_weak1_1_1_a_r_c4___base.html#29f63756c5afe80ab801d42f4b5ee1ee">m_x</a> = <a class="code" href="class_weak1_1_1_a_r_c4___base.html#2a6f0319c66fc26f25d5731c90f17381">m_y</a> = 0;<a name="l00024"></a>00024 }<a name="l00025"></a>00025 <a name="l00026"></a><a class="code" href="class_weak1_1_1_a_r_c4___base.html#6f4a58b7d62900729eee7c7532851378">00026</a> <span class="keywordtype">void</span> <a class="code" href="class_weak1_1_1_a_r_c4___base.html#6f4a58b7d62900729eee7c7532851378">ARC4_Base::UncheckedSetKey</a>(<span class="keyword">const</span> byte *key, <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> keyLen, <span class="keyword">const</span> <a class="code" href="class_name_value_pairs.html" title="interface for retrieving values given their names">NameValuePairs</a> &params)<a name="l00027"></a>00027 {<a name="l00028"></a>00028 <a class="code" href="class_simple_keying_interface.html#719efcf12f0de461b951830b8131b36a">AssertValidKeyLength</a>(keyLen);<a name="l00029"></a>00029 <a name="l00030"></a>00030 <a class="code" href="class_weak1_1_1_a_r_c4___base.html#29f63756c5afe80ab801d42f4b5ee1ee">m_x</a> = 1;<a name="l00031"></a>00031 <a class="code" href="class_weak1_1_1_a_r_c4___base.html#2a6f0319c66fc26f25d5731c90f17381">m_y</a> = 0;<a name="l00032"></a>00032 <a name="l00033"></a>00033 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> i;<a name="l00034"></a>00034 <span class="keywordflow">for</span> (i=0; i<256; i++)<a name="l00035"></a>00035 <a class="code" href="class_weak1_1_1_a_r_c4___base.html#fda46a15541cdc4d513ec22431fe105b">m_state</a>[i] = i;<a name="l00036"></a>00036 <a name="l00037"></a>00037 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> keyIndex = 0, stateIndex = 0;<a name="l00038"></a>00038 <span class="keywordflow">for</span> (i=0; i<256; i++)<a name="l00039"></a>00039 {<a name="l00040"></a>00040 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> a = <a class="code" href="class_weak1_1_1_a_r_c4___base.html#fda46a15541cdc4d513ec22431fe105b">m_state</a>[i];<a name="l00041"></a>00041 stateIndex += key[keyIndex] + a;<a name="l00042"></a>00042 stateIndex &= 0xff;<a name="l00043"></a>00043 <a class="code" href="class_weak1_1_1_a_r_c4___base.html#fda46a15541cdc4d513ec22431fe105b">m_state</a>[i] = <a class="code" href="class_weak1_1_1_a_r_c4___base.html#fda46a15541cdc4d513ec22431fe105b">m_state</a>[stateIndex];<a name="l00044"></a>00044 <a class="code" href="class_weak1_1_1_a_r_c4___base.html#fda46a15541cdc4d513ec22431fe105b">m_state</a>[stateIndex] = a;<a name="l00045"></a>00045 <span class="keywordflow">if</span> (++keyIndex >= keyLen)<a name="l00046"></a>00046 keyIndex = 0;<a name="l00047"></a>00047 }<a name="l00048"></a>00048 <a name="l00049"></a>00049 <span class="keywordtype">int</span> discardBytes = params.<a class="code" href="class_name_value_pairs.html#7ddb654b7afcd1a04422a7b4b01366d9" title="get a named value with type int, with default">GetIntValueWithDefault</a>(<span class="stringliteral">"DiscardBytes"</span>, <a class="code" href="class_weak1_1_1_a_r_c4___base.html#766b65658e5c34647844711461ce2e39">GetDefaultDiscardBytes</a>());<a name="l00050"></a>00050 <a class="code" href="class_weak1_1_1_a_r_c4___base.html#e9e92ea2c4591c2ceea61b3babea8504" title="generate and discard n bytes">DiscardBytes</a>(discardBytes);<a name="l00051"></a>00051 }<a name="l00052"></a>00052 <a name="l00053"></a>00053 <span class="keyword">template</span> <<span class="keyword">class</span> T><a name="l00054"></a>00054 <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> MakeByte(T &x, T &y, byte *s)<a name="l00055"></a>00055 {<a name="l00056"></a>00056 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> a = s[x];<a name="l00057"></a>00057 y = (y+a) & 0xff;<a name="l00058"></a>00058 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> b = s[y];<a name="l00059"></a>00059 s[x] = b;<a name="l00060"></a>00060 s[y] = a;<a name="l00061"></a>00061 x = (x+1) & 0xff;<a name="l00062"></a>00062 <span class="keywordflow">return</span> s[(a+b) & 0xff];<a name="l00063"></a>00063 }<a name="l00064"></a>00064 <a name="l00065"></a><a class="code" href="class_weak1_1_1_a_r_c4___base.html#05b6c97fbbd0dd2636a330242dd768dc">00065</a> <span class="keywordtype">void</span> <a class="code" href="class_weak1_1_1_a_r_c4___base.html#05b6c97fbbd0dd2636a330242dd768dc" title="generate random array of bytes">ARC4_Base::GenerateBlock</a>(byte *output, <span class="keywordtype">size_t</span> size)<a name="l00066"></a>00066 {<a name="l00067"></a>00067 <span class="keywordflow">while</span> (size--)<a name="l00068"></a>00068 *output++ = MakeByte(<a class="code" href="class_weak1_1_1_a_r_c4___base.html#29f63756c5afe80ab801d42f4b5ee1ee">m_x</a>, <a class="code" href="class_weak1_1_1_a_r_c4___base.html#2a6f0319c66fc26f25d5731c90f17381">m_y</a>, <a class="code" href="class_weak1_1_1_a_r_c4___base.html#fda46a15541cdc4d513ec22431fe105b">m_state</a>);<a name="l00069"></a>00069 }<a name="l00070"></a>00070 <a name="l00071"></a><a class="code" href="class_weak1_1_1_a_r_c4___base.html#a20124dfc1bac5050b1cd922e552ba95">00071</a> <span class="keywordtype">void</span> <a class="code" href="class_weak1_1_1_a_r_c4___base.html#a20124dfc1bac5050b1cd922e552ba95" title="encrypt or decrypt an array of bytes of specified length">ARC4_Base::ProcessData</a>(byte *outString, <span class="keyword">const</span> byte *inString, <span class="keywordtype">size_t</span> length)<a name="l00072"></a>00072 {<a name="l00073"></a>00073 <span class="keywordflow">if</span> (length == 0)<a name="l00074"></a>00074 <span class="keywordflow">return</span>;<a name="l00075"></a>00075 <a name="l00076"></a>00076 byte *<span class="keyword">const</span> s = <a class="code" href="class_weak1_1_1_a_r_c4___base.html#fda46a15541cdc4d513ec22431fe105b">m_state</a>;<a name="l00077"></a>00077 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> x = <a class="code" href="class_weak1_1_1_a_r_c4___base.html#29f63756c5afe80ab801d42f4b5ee1ee">m_x</a>;<a name="l00078"></a>00078 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> y = <a class="code" href="class_weak1_1_1_a_r_c4___base.html#2a6f0319c66fc26f25d5731c90f17381">m_y</a>;<a name="l00079"></a>00079 <a name="l00080"></a>00080 <span class="keywordflow">if</span> (inString == outString)<a name="l00081"></a>00081 {<a name="l00082"></a>00082 <span class="keywordflow">do</span><a name="l00083"></a>00083 {<a name="l00084"></a>00084 *outString++ ^= MakeByte(x, y, s);<a name="l00085"></a>00085 } <span class="keywordflow">while</span> (--length);<a name="l00086"></a>00086 }<a name="l00087"></a>00087 <span class="keywordflow">else</span><a name="l00088"></a>00088 {<a name="l00089"></a>00089 <span class="keywordflow">do</span><a name="l00090"></a>00090 {<a name="l00091"></a>00091 *outString++ = *inString++ ^ MakeByte(x, y, s);<a name="l00092"></a>00092 }<a name="l00093"></a>00093 <span class="keywordflow">while</span>(--length);<a name="l00094"></a>00094 }<a name="l00095"></a>00095 <a name="l00096"></a>00096 <a class="code" href="class_weak1_1_1_a_r_c4___base.html#29f63756c5afe80ab801d42f4b5ee1ee">m_x</a> = x;<a name="l00097"></a>00097 <a class="code" href="class_weak1_1_1_a_r_c4___base.html#2a6f0319c66fc26f25d5731c90f17381">m_y</a> = y;<a name="l00098"></a>00098 }<a name="l00099"></a>00099 <a name="l00100"></a><a class="code" href="class_weak1_1_1_a_r_c4___base.html#e9e92ea2c4591c2ceea61b3babea8504">00100</a> <span class="keywordtype">void</span> <a class="code" href="class_weak1_1_1_a_r_c4___base.html#e9e92ea2c4591c2ceea61b3babea8504" title="generate and discard n bytes">ARC4_Base::DiscardBytes</a>(<span class="keywordtype">size_t</span> length)<a name="l00101"></a>00101 {<a name="l00102"></a>00102 <span class="keywordflow">if</span> (length == 0)<a name="l00103"></a>00103 <span class="keywordflow">return</span>;<a name="l00104"></a>00104 <a name="l00105"></a>00105 byte *<span class="keyword">const</span> s = <a class="code" href="class_weak1_1_1_a_r_c4___base.html#fda46a15541cdc4d513ec22431fe105b">m_state</a>;<a name="l00106"></a>00106 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> x = <a class="code" href="class_weak1_1_1_a_r_c4___base.html#29f63756c5afe80ab801d42f4b5ee1ee">m_x</a>;<a name="l00107"></a>00107 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> y = <a class="code" href="class_weak1_1_1_a_r_c4___base.html#2a6f0319c66fc26f25d5731c90f17381">m_y</a>;<a name="l00108"></a>00108 <a name="l00109"></a>00109 <span class="keywordflow">do</span><a name="l00110"></a>00110 {<a name="l00111"></a>00111 MakeByte(x, y, s);<a name="l00112"></a>00112 }<a name="l00113"></a>00113 <span class="keywordflow">while</span>(--length);<a name="l00114"></a>00114 <a name="l00115"></a>00115 <a class="code" href="class_weak1_1_1_a_r_c4___base.html#29f63756c5afe80ab801d42f4b5ee1ee">m_x</a> = x;<a name="l00116"></a>00116 <a class="code" href="class_weak1_1_1_a_r_c4___base.html#2a6f0319c66fc26f25d5731c90f17381">m_y</a> = y;<a name="l00117"></a>00117 }<a name="l00118"></a>00118 <a name="l00119"></a>00119 }<a name="l00120"></a>00120 NAMESPACE_END</pre></div><hr size="1"><address style="text-align: right;"><small>Generated on Fri Jun 1 11:11:19 2007 for Crypto++ by <a href="http://www.doxygen.org/index.html"><img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.5.2 </small></address></body></html>⌨️ 快捷键说明
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