<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/> <meta http-equiv="X-UA-Compatible" content="IE=9"/> <meta name="generator" content="Doxygen 1.8.14"/> <meta name="viewport" content="width=device-width, initial-scale=1"/> <title>Crypto++: arc4.cpp Source File</title> <link href="tabs.css" rel="stylesheet" type="text/css"/> <script type="text/javascript" src="jquery.js"></script> <script type="text/javascript" src="dynsections.js"></script> <link href="doxygen.css" rel="stylesheet" type="text/css" /> </head> <body> <div id="top"><!-- do not remove this div, it is closed by doxygen! --> <div id="titlearea"> <table cellspacing="0" cellpadding="0"> <tbody> <tr style="height: 56px;"> <td id="projectalign" style="padding-left: 0.5em;"> <div id="projectname">Crypto++  <span id="projectnumber">7.0</span> </div> <div id="projectbrief">Free C++ class library of cryptographic schemes</div> </td> </tr> </tbody> </table> </div> <!-- end header part --> <!-- Generated by Doxygen 1.8.14 --> <script type="text/javascript" src="menudata.js"></script> <script type="text/javascript" src="menu.js"></script> <script type="text/javascript"> /* @license magnet:?xt=urn:btih:cf05388f2679ee054f2beb29a391d25f4e673ac3&dn=gpl-2.0.txt GPL-v2 */ $(function() { initMenu('',false,false,'search.php','Search'); }); /* @license-end */</script> <div id="main-nav"></div> </div><!-- top --> <div class="header"> <div class="headertitle"> <div class="title">arc4.cpp</div> </div> </div><!--header--> <div class="contents"> <div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno"> 1</span> <span class="comment">// arc4.cpp - originally written and placed in the public domain by Wei Dai</span></div><div class="line"><a name="l00002"></a><span class="lineno"> 2</span> </div><div class="line"><a name="l00003"></a><span class="lineno"> 3</span> <span class="comment">// The ARC4 algorithm was first revealed in an anonymous email to the</span></div><div class="line"><a name="l00004"></a><span class="lineno"> 4</span> <span class="comment">// cypherpunks mailing list. This file originally contained some</span></div><div class="line"><a name="l00005"></a><span class="lineno"> 5</span> <span class="comment">// code copied from this email. The code has since been rewritten in order</span></div><div class="line"><a name="l00006"></a><span class="lineno"> 6</span> <span class="comment">// to clarify the copyright status of this file. It should now be</span></div><div class="line"><a name="l00007"></a><span class="lineno"> 7</span> <span class="comment">// completely in the public domain.</span></div><div class="line"><a name="l00008"></a><span class="lineno"> 8</span> </div><div class="line"><a name="l00009"></a><span class="lineno"> 9</span> <span class="preprocessor">#include "<a class="code" href="pch_8h.html">pch.h</a>"</span></div><div class="line"><a name="l00010"></a><span class="lineno"> 10</span> <span class="preprocessor">#define CRYPTOPP_ENABLE_NAMESPACE_WEAK 1</span></div><div class="line"><a name="l00011"></a><span class="lineno"> 11</span> <span class="preprocessor">#include "<a class="code" href="arc4_8h.html">arc4.h</a>"</span></div><div class="line"><a name="l00012"></a><span class="lineno"> 12</span> </div><div class="line"><a name="l00013"></a><span class="lineno"> 13</span> NAMESPACE_BEGIN(<a class="code" href="namespace_crypto_p_p.html">CryptoPP</a>)</div><div class="line"><a name="l00014"></a><span class="lineno"><a class="line" href="namespace_weak.html"> 14</a></span> namespace Weak1 {</div><div class="line"><a name="l00015"></a><span class="lineno"> 15</span> </div><div class="line"><a name="l00016"></a><span class="lineno"> 16</span> <span class="preprocessor">#if defined(CRYPTOPP_DEBUG) && !defined(CRYPTOPP_DOXYGEN_PROCESSING)</span></div><div class="line"><a name="l00017"></a><span class="lineno"> 17</span> <span class="keywordtype">void</span> ARC4_TestInstantiations()</div><div class="line"><a name="l00018"></a><span class="lineno"> 18</span> {</div><div class="line"><a name="l00019"></a><span class="lineno"> 19</span>  <a class="code" href="class_weak_1_1_a_r_c4.html">ARC4</a> x;</div><div class="line"><a name="l00020"></a><span class="lineno"> 20</span> }</div><div class="line"><a name="l00021"></a><span class="lineno"> 21</span> <span class="preprocessor">#endif</span></div><div class="line"><a name="l00022"></a><span class="lineno"> 22</span> </div><div class="line"><a name="l00023"></a><span class="lineno"> 23</span> ARC4_Base::~ARC4_Base()</div><div class="line"><a name="l00024"></a><span class="lineno"> 24</span> {</div><div class="line"><a name="l00025"></a><span class="lineno"> 25</span>  m_x = m_y = 0;</div><div class="line"><a name="l00026"></a><span class="lineno"> 26</span> }</div><div class="line"><a name="l00027"></a><span class="lineno"> 27</span> </div><div class="line"><a name="l00028"></a><span class="lineno"> 28</span> <span class="keywordtype">void</span> ARC4_Base::UncheckedSetKey(<span class="keyword">const</span> byte *key, <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> length, <span class="keyword">const</span> <a class="code" href="class_name_value_pairs.html">NameValuePairs</a> &params)</div><div class="line"><a name="l00029"></a><span class="lineno"> 29</span> {</div><div class="line"><a name="l00030"></a><span class="lineno"> 30</span>  AssertValidKeyLength(length);</div><div class="line"><a name="l00031"></a><span class="lineno"> 31</span> </div><div class="line"><a name="l00032"></a><span class="lineno"> 32</span>  m_x = 1;</div><div class="line"><a name="l00033"></a><span class="lineno"> 33</span>  m_y = 0;</div><div class="line"><a name="l00034"></a><span class="lineno"> 34</span> </div><div class="line"><a name="l00035"></a><span class="lineno"> 35</span>  <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> i;</div><div class="line"><a name="l00036"></a><span class="lineno"> 36</span>  <span class="keywordflow">for</span> (i=0; i<256; i++)</div><div class="line"><a name="l00037"></a><span class="lineno"> 37</span>  m_state[i] = byte(i);</div><div class="line"><a name="l00038"></a><span class="lineno"> 38</span> </div><div class="line"><a name="l00039"></a><span class="lineno"> 39</span>  <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> keyIndex = 0, stateIndex = 0;</div><div class="line"><a name="l00040"></a><span class="lineno"> 40</span>  <span class="keywordflow">for</span> (i=0; i<256; i++)</div><div class="line"><a name="l00041"></a><span class="lineno"> 41</span>  {</div><div class="line"><a name="l00042"></a><span class="lineno"> 42</span>  <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> a = m_state[i];</div><div class="line"><a name="l00043"></a><span class="lineno"> 43</span>  stateIndex += key[keyIndex] + a;</div><div class="line"><a name="l00044"></a><span class="lineno"> 44</span>  stateIndex &= 0xff;</div><div class="line"><a name="l00045"></a><span class="lineno"> 45</span>  m_state[i] = m_state[stateIndex];</div><div class="line"><a name="l00046"></a><span class="lineno"> 46</span>  m_state[stateIndex] = byte(a);</div><div class="line"><a name="l00047"></a><span class="lineno"> 47</span>  <span class="keywordflow">if</span> (++keyIndex >= length)</div><div class="line"><a name="l00048"></a><span class="lineno"> 48</span>  keyIndex = 0;</div><div class="line"><a name="l00049"></a><span class="lineno"> 49</span>  }</div><div class="line"><a name="l00050"></a><span class="lineno"> 50</span> </div><div class="line"><a name="l00051"></a><span class="lineno"> 51</span>  <span class="keywordtype">int</span> discardBytes = params.<a class="code" href="class_name_value_pairs.html#a7ddb654b7afcd1a04422a7b4b01366d9">GetIntValueWithDefault</a>(<span class="stringliteral">"DiscardBytes"</span>, GetDefaultDiscardBytes());</div><div class="line"><a name="l00052"></a><span class="lineno"> 52</span>  DiscardBytes(discardBytes);</div><div class="line"><a name="l00053"></a><span class="lineno"> 53</span> }</div><div class="line"><a name="l00054"></a><span class="lineno"> 54</span> </div><div class="line"><a name="l00055"></a><span class="lineno"> 55</span> <span class="keyword">template</span> <<span class="keyword">class</span> T></div><div class="line"><a name="l00056"></a><span class="lineno"> 56</span> <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)</div><div class="line"><a name="l00057"></a><span class="lineno"> 57</span> {</div><div class="line"><a name="l00058"></a><span class="lineno"> 58</span>  <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> a = s[x];</div><div class="line"><a name="l00059"></a><span class="lineno"> 59</span>  y = byte((y+a) & 0xff);</div><div class="line"><a name="l00060"></a><span class="lineno"> 60</span>  <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> b = s[y];</div><div class="line"><a name="l00061"></a><span class="lineno"> 61</span>  s[x] = byte(b);</div><div class="line"><a name="l00062"></a><span class="lineno"> 62</span>  s[y] = byte(a);</div><div class="line"><a name="l00063"></a><span class="lineno"> 63</span>  x = byte((x+1) & 0xff);</div><div class="line"><a name="l00064"></a><span class="lineno"> 64</span>  <span class="keywordflow">return</span> s[(a+b) & 0xff];</div><div class="line"><a name="l00065"></a><span class="lineno"> 65</span> }</div><div class="line"><a name="l00066"></a><span class="lineno"> 66</span> </div><div class="line"><a name="l00067"></a><span class="lineno"><a class="line" href="class_weak_1_1_a_r_c4___base.html#a05b6c97fbbd0dd2636a330242dd768dc"> 67</a></span> <span class="keywordtype">void</span> ARC4_Base::GenerateBlock(byte *output, <span class="keywordtype">size_t</span> size)</div><div class="line"><a name="l00068"></a><span class="lineno"> 68</span> {</div><div class="line"><a name="l00069"></a><span class="lineno"> 69</span>  <span class="keywordflow">while</span> (size--)</div><div class="line"><a name="l00070"></a><span class="lineno"> 70</span>  *output++ = <span class="keyword">static_cast<</span>byte<span class="keyword">></span>(MakeByte(m_x, m_y, m_state));</div><div class="line"><a name="l00071"></a><span class="lineno"> 71</span> }</div><div class="line"><a name="l00072"></a><span class="lineno"> 72</span> </div><div class="line"><a name="l00073"></a><span class="lineno"><a class="line" href="class_weak_1_1_a_r_c4___base.html#aa20124dfc1bac5050b1cd922e552ba95"> 73</a></span> <span class="keywordtype">void</span> ARC4_Base::ProcessData(byte *outString, <span class="keyword">const</span> byte *inString, <span class="keywordtype">size_t</span> length)</div><div class="line"><a name="l00074"></a><span class="lineno"> 74</span> {</div><div class="line"><a name="l00075"></a><span class="lineno"> 75</span>  <span class="keywordflow">if</span> (length == 0)</div><div class="line"><a name="l00076"></a><span class="lineno"> 76</span>  <span class="keywordflow">return</span>;</div><div class="line"><a name="l00077"></a><span class="lineno"> 77</span> </div><div class="line"><a name="l00078"></a><span class="lineno"> 78</span>  byte *<span class="keyword">const</span> s = m_state;</div><div class="line"><a name="l00079"></a><span class="lineno"> 79</span>  <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> x = m_x;</div><div class="line"><a name="l00080"></a><span class="lineno"> 80</span>  <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> y = m_y;</div><div class="line"><a name="l00081"></a><span class="lineno"> 81</span> </div><div class="line"><a name="l00082"></a><span class="lineno"> 82</span>  <span class="keywordflow">if</span> (inString == outString)</div><div class="line"><a name="l00083"></a><span class="lineno"> 83</span>  {</div><div class="line"><a name="l00084"></a><span class="lineno"> 84</span>  <span class="keywordflow">do</span></div><div class="line"><a name="l00085"></a><span class="lineno"> 85</span>  {</div><div class="line"><a name="l00086"></a><span class="lineno"> 86</span>  *outString++ ^= MakeByte(x, y, s);</div><div class="line"><a name="l00087"></a><span class="lineno"> 87</span>  } <span class="keywordflow">while</span> (--length);</div><div class="line"><a name="l00088"></a><span class="lineno"> 88</span>  }</div><div class="line"><a name="l00089"></a><span class="lineno"> 89</span>  <span class="keywordflow">else</span></div><div class="line"><a name="l00090"></a><span class="lineno"> 90</span>  {</div><div class="line"><a name="l00091"></a><span class="lineno"> 91</span>  <span class="keywordflow">do</span></div><div class="line"><a name="l00092"></a><span class="lineno"> 92</span>  {</div><div class="line"><a name="l00093"></a><span class="lineno"> 93</span>  *outString++ = *inString++ ^ byte(MakeByte(x, y, s));</div><div class="line"><a name="l00094"></a><span class="lineno"> 94</span>  }</div><div class="line"><a name="l00095"></a><span class="lineno"> 95</span>  <span class="keywordflow">while</span>(--length);</div><div class="line"><a name="l00096"></a><span class="lineno"> 96</span>  }</div><div class="line"><a name="l00097"></a><span class="lineno"> 97</span> </div><div class="line"><a name="l00098"></a><span class="lineno"> 98</span>  m_x = byte(x);</div><div class="line"><a name="l00099"></a><span class="lineno"> 99</span>  m_y = byte(y);</div><div class="line"><a name="l00100"></a><span class="lineno"> 100</span> }</div><div class="line"><a name="l00101"></a><span class="lineno"> 101</span> </div><div class="line"><a name="l00102"></a><span class="lineno"><a class="line" href="class_weak_1_1_a_r_c4___base.html#ae9e92ea2c4591c2ceea61b3babea8504"> 102</a></span> <span class="keywordtype">void</span> ARC4_Base::DiscardBytes(<span class="keywordtype">size_t</span> n)</div><div class="line"><a name="l00103"></a><span class="lineno"> 103</span> {</div><div class="line"><a name="l00104"></a><span class="lineno"> 104</span>  <span class="keywordflow">if</span> (n == 0)</div><div class="line"><a name="l00105"></a><span class="lineno"> 105</span>  <span class="keywordflow">return</span>;</div><div class="line"><a name="l00106"></a><span class="lineno"> 106</span> </div><div class="line"><a name="l00107"></a><span class="lineno"> 107</span>  byte *<span class="keyword">const</span> s = m_state;</div><div class="line"><a name="l00108"></a><span class="lineno"> 108</span>  <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> x = m_x;</div><div class="line"><a name="l00109"></a><span class="lineno"> 109</span>  <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> y = m_y;</div><div class="line"><a name="l00110"></a><span class="lineno"> 110</span> </div><div class="line"><a name="l00111"></a><span class="lineno"> 111</span>  <span class="keywordflow">do</span></div><div class="line"><a name="l00112"></a><span class="lineno"> 112</span>  {</div><div class="line"><a name="l00113"></a><span class="lineno"> 113</span>  MakeByte(x, y, s);</div><div class="line"><a name="l00114"></a><span class="lineno"> 114</span>  }</div><div class="line"><a name="l00115"></a><span class="lineno"> 115</span>  <span class="keywordflow">while</span>(--n);</div><div class="line"><a name="l00116"></a><span class="lineno"> 116</span> </div><div class="line"><a name="l00117"></a><span class="lineno"> 117</span>  m_x = byte(x);</div><div class="line"><a name="l00118"></a><span class="lineno"> 118</span>  m_y = byte(y);</div><div class="line"><a name="l00119"></a><span class="lineno"> 119</span> }</div><div class="line"><a name="l00120"></a><span class="lineno"> 120</span> </div><div class="line"><a name="l00121"></a><span class="lineno"> 121</span> }</div><div class="line"><a name="l00122"></a><span class="lineno"> 122</span> NAMESPACE_END</div><div class="ttc" id="class_name_value_pairs_html_a7ddb654b7afcd1a04422a7b4b01366d9"><div class="ttname"><a href="class_name_value_pairs.html#a7ddb654b7afcd1a04422a7b4b01366d9">NameValuePairs::GetIntValueWithDefault</a></div><div class="ttdeci">int GetIntValueWithDefault(const char *name, int defaultValue) const</div><div class="ttdoc">Get a named value with type int, with default. </div><div class="ttdef"><b>Definition:</b> <a href="cryptlib_8h_source.html#l00392">cryptlib.h:392</a></div></div> <div class="ttc" id="class_weak_1_1_a_r_c4_html"><div class="ttname"><a href="class_weak_1_1_a_r_c4.html">Weak::ARC4</a></div><div class="ttdoc">Alleged RC4. </div><div class="ttdef"><b>Definition:</b> <a href="arc4_8h_source.html#l00052">arc4.h:52</a></div></div> <div class="ttc" id="pch_8h_html"><div class="ttname"><a href="pch_8h.html">pch.h</a></div><div class="ttdoc">Precompiled header file. </div></div> <div class="ttc" id="namespace_crypto_p_p_html"><div class="ttname"><a href="namespace_crypto_p_p.html">CryptoPP</a></div><div class="ttdoc">Crypto++ library namespace. </div></div> <div class="ttc" id="arc4_8h_html"><div class="ttname"><a href="arc4_8h.html">arc4.h</a></div><div class="ttdoc">Classes for ARC4 cipher. </div></div> <div class="ttc" id="class_name_value_pairs_html"><div class="ttname"><a href="class_name_value_pairs.html">NameValuePairs</a></div><div class="ttdoc">Interface for retrieving values given their names. </div><div class="ttdef"><b>Definition:</b> <a href="cryptlib_8h_source.html#l00290">cryptlib.h:290</a></div></div> </div><!-- fragment --></div><!-- contents --> <!-- start footer part --> <hr class="footer"/><address class="footer"><small> Generated on Sun Sep 16 2018 07:57:45 for Crypto++ by  <a href="http://www.doxygen.org/index.html"> <img class="footer" src="doxygen.png" alt="doxygen"/> </a> 1.8.14 </small></address> </body> </html>