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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++: ecp.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>ecp.cpp</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">// ecp.cpp - written and placed in the public domain by Wei Dai</span><a name="l00002"></a>00002 <a name="l00003"></a>00003 <span class="preprocessor">#include "pch.h"</span><a name="l00004"></a>00004 <a name="l00005"></a>00005 <span class="preprocessor">#ifndef CRYPTOPP_IMPORTS</span><a name="l00006"></a>00006 <span class="preprocessor"></span><a name="l00007"></a>00007 <span class="preprocessor">#include "ecp.h"</span><a name="l00008"></a>00008 <span class="preprocessor">#include "asn.h"</span><a name="l00009"></a>00009 <span class="preprocessor">#include "nbtheory.h"</span><a name="l00010"></a>00010 <a name="l00011"></a>00011 <span class="preprocessor">#include "algebra.cpp"</span><a name="l00012"></a>00012 <a name="l00013"></a>00013 NAMESPACE_BEGIN(CryptoPP)<a name="l00014"></a>00014 <a name="l00015"></a>00015 ANONYMOUS_NAMESPACE_BEGIN<a name="l00016"></a>00016 static inline <a class="code" href="class_e_c_p.html" title="Elliptic Curve over GF(p), where p is prime.">ECP</a>::Point ToMontgomery(const <a class="code" href="class_modular_arithmetic.html" title="ring of congruence classes modulo n">ModularArithmetic</a> &mr, const <a class="code" href="class_e_c_p.html" title="Elliptic Curve over GF(p), where p is prime.">ECP</a>::Point &P)<a name="l00017"></a>00017 {<a name="l00018"></a>00018 <span class="keywordflow">return</span> P.identity ? P : <a class="code" href="class_e_c_p.html#99c34a437007f32af4e6c4ae275358ea">ECP::Point</a>(mr.ConvertIn(P.x), mr.ConvertIn(P.y));<a name="l00019"></a>00019 }<a name="l00020"></a>00020 <a name="l00021"></a>00021 <span class="keyword">static</span> <span class="keyword">inline</span> <a class="code" href="struct_e_c_p_point.html" title="Elliptical Curve Point.">ECP::Point</a> FromMontgomery(<span class="keyword">const</span> <a class="code" href="class_modular_arithmetic.html" title="ring of congruence classes modulo n">ModularArithmetic</a> &mr, <span class="keyword">const</span> <a class="code" href="struct_e_c_p_point.html" title="Elliptical Curve Point.">ECP::Point</a> &P)<a name="l00022"></a>00022 {<a name="l00023"></a>00023 <span class="keywordflow">return</span> P.<a class="code" href="struct_e_c_p_point.html#806dedcf077e22de7904ccfd7987bcf9">identity</a> ? P : <a class="code" href="class_e_c_p.html#99c34a437007f32af4e6c4ae275358ea">ECP::Point</a>(mr.<a class="code" href="class_modular_arithmetic.html#bbd97fd2abfb869063f51cfdeb769c71">ConvertOut</a>(P.<a class="code" href="struct_e_c_p_point.html#24bbcc7eb375ebe2b46d2ac9ee6bb0a8">x</a>), mr.<a class="code" href="class_modular_arithmetic.html#bbd97fd2abfb869063f51cfdeb769c71">ConvertOut</a>(P.<a class="code" href="struct_e_c_p_point.html#b47b82046f543e809bd90d78bf2c85bf">y</a>));<a name="l00024"></a>00024 }<a name="l00025"></a>00025 NAMESPACE_END<a name="l00026"></a>00026 <a name="l00027"></a>00027 <a class="code" href="class_e_c_p.html#50e65de68e93c6bf2e174c8dc2322731">ECP::ECP</a>(<span class="keyword">const</span> <a class="code" href="class_e_c_p.html" title="Elliptic Curve over GF(p), where p is prime.">ECP</a> &ecp, <span class="keywordtype">bool</span> convertToMontgomeryRepresentation)<a name="l00028"></a>00028 {<a name="l00029"></a>00029 <span class="keywordflow">if</span> (convertToMontgomeryRepresentation && !ecp.<a class="code" href="class_e_c_p.html#e996fce212244df79b83a587317f7423">GetField</a>().<a class="code" href="class_modular_arithmetic.html#7a93adfe41f5545dcfaf3ee9f2b49bc3">IsMontgomeryRepresentation</a>())<a name="l00030"></a>00030 {<a name="l00031"></a>00031 m_fieldPtr.<a class="code" href="classmember__ptr.html#0191c833924d93e9093b07bab31010fe">reset</a>(<span class="keyword">new</span> <a class="code" href="class_montgomery_representation.html" title="do modular arithmetics in Montgomery representation for increased speed">MontgomeryRepresentation</a>(ecp.<a class="code" href="class_e_c_p.html#e996fce212244df79b83a587317f7423">GetField</a>().<a class="code" href="class_modular_arithmetic.html#71a51e5b665bf7fb89af2ccba19f0043">GetModulus</a>()));<a name="l00032"></a>00032 m_a = <a class="code" href="class_e_c_p.html#e996fce212244df79b83a587317f7423">GetField</a>().<a class="code" href="class_modular_arithmetic.html#6d504c7166a5eab47a74b86ce8cc782b">ConvertIn</a>(ecp.<a class="code" href="class_e_c_p.html#20079b1eb4cc7648cd53deab66aef43d">m_a</a>);<a name="l00033"></a>00033 m_b = <a class="code" href="class_e_c_p.html#e996fce212244df79b83a587317f7423">GetField</a>().<a class="code" href="class_modular_arithmetic.html#6d504c7166a5eab47a74b86ce8cc782b">ConvertIn</a>(ecp.<a class="code" href="class_e_c_p.html#7455165c1e3fc28e4f030246ac6ea6fe">m_b</a>);<a name="l00034"></a>00034 }<a name="l00035"></a>00035 <span class="keywordflow">else</span><a name="l00036"></a>00036 operator=(ecp);<a name="l00037"></a>00037 }<a name="l00038"></a>00038 <a name="l00039"></a>00039 <a class="code" href="class_e_c_p.html#50e65de68e93c6bf2e174c8dc2322731">ECP::ECP</a>(<a class="code" href="class_buffered_transformation.html" title="interface for buffered transformations">BufferedTransformation</a> &bt)<a name="l00040"></a>00040 : m_fieldPtr(new <a class="code" href="class_e_c_p.html#746aebbc43b99972e5a647ebabbbc931">Field</a>(bt))<a name="l00041"></a>00041 {<a name="l00042"></a>00042 <a class="code" href="class_b_e_r_sequence_decoder.html" title="BER Sequence Decoder.">BERSequenceDecoder</a> seq(bt);<a name="l00043"></a>00043 GetField().BERDecodeElement(seq, m_a);<a name="l00044"></a>00044 GetField().BERDecodeElement(seq, m_b);<a name="l00045"></a>00045 <span class="comment">// skip optional seed</span><a name="l00046"></a>00046 <span class="keywordflow">if</span> (!seq.EndReached())<a name="l00047"></a>00047 {<a name="l00048"></a>00048 <a class="code" href="class_sec_block.html" title="a block of memory allocated using A">SecByteBlock</a> seed;<a name="l00049"></a>00049 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> unused;<a name="l00050"></a>00050 BERDecodeBitString(seq, seed, unused);<a name="l00051"></a>00051 }<a name="l00052"></a>00052 seq.MessageEnd();<a name="l00053"></a>00053 }<a name="l00054"></a>00054 <a name="l00055"></a>00055 <span class="keywordtype">void</span> ECP::DEREncode(<a class="code" href="class_buffered_transformation.html" title="interface for buffered transformations">BufferedTransformation</a> &bt)<span class="keyword"> const</span><a name="l00056"></a>00056 <span class="keyword"></span>{<a name="l00057"></a>00057 <a class="code" href="class_e_c_p.html#e996fce212244df79b83a587317f7423">GetField</a>().<a class="code" href="class_modular_arithmetic.html#ba88499eea9ee645c04cab392bbbd977">DEREncode</a>(bt);<a name="l00058"></a>00058 <a class="code" href="class_d_e_r_sequence_encoder.html" title="DER Sequence Encoder.">DERSequenceEncoder</a> seq(bt);<a name="l00059"></a>00059 <a class="code" href="class_e_c_p.html#e996fce212244df79b83a587317f7423">GetField</a>().<a class="code" href="class_modular_arithmetic.html#27dc1aa752d09041ed66391dff7086cc">DEREncodeElement</a>(seq, m_a);<a name="l00060"></a>00060 <a class="code" href="class_e_c_p.html#e996fce212244df79b83a587317f7423">GetField</a>().<a class="code" href="class_modular_arithmetic.html#27dc1aa752d09041ed66391dff7086cc">DEREncodeElement</a>(seq, m_b);<a name="l00061"></a>00061 seq.MessageEnd();<a name="l00062"></a>00062 }<a name="l00063"></a>00063 <a name="l00064"></a>00064 <span class="keywordtype">bool</span> ECP::DecodePoint(<a class="code" href="struct_e_c_p_point.html" title="Elliptical Curve Point.">ECP::Point</a> &P, <span class="keyword">const</span> byte *encodedPoint, <span class="keywordtype">size_t</span> encodedPointLen)<span class="keyword"> const</span><a name="l00065"></a>00065 <span class="keyword"></span>{<a name="l00066"></a>00066 <a class="code" href="class_string_store.html" title="string-based implementation of Store interface">StringStore</a> store(encodedPoint, encodedPointLen);<a name="l00067"></a>00067 <span class="keywordflow">return</span> DecodePoint(P, store, encodedPointLen);<a name="l00068"></a>00068 }<a name="l00069"></a>00069 <a name="l00070"></a>00070 <span class="keywordtype">bool</span> ECP::DecodePoint(<a class="code" href="struct_e_c_p_point.html" title="Elliptical Curve Point.">ECP::Point</a> &P, <a class="code" href="class_buffered_transformation.html" title="interface for buffered transformations">BufferedTransformation</a> &bt, <span class="keywordtype">size_t</span> encodedPointLen)<span class="keyword"> const</span><a name="l00071"></a>00071 <span class="keyword"></span>{<a name="l00072"></a>00072 byte type;<a name="l00073"></a>00073 <span class="keywordflow">if</span> (encodedPointLen < 1 || !bt.<a class="code" href="class_buffered_transformation.html#9e1ad913c8fe697d269f408a7d5928fc" title="try to retrieve a single byte">Get</a>(type))<a name="l00074"></a>00074 <span class="keywordflow">return</span> <span class="keyword">false</span>;<a name="l00075"></a>00075 <a name="l00076"></a>00076 <span class="keywordflow">switch</span> (type)<a name="l00077"></a>00077 {<a name="l00078"></a>00078 <span class="keywordflow">case</span> 0:<a name="l00079"></a>00079 P.<a class="code" href="struct_e_c_p_point.html#806dedcf077e22de7904ccfd7987bcf9">identity</a> = <span class="keyword">true</span>;<a name="l00080"></a>00080 <span class="keywordflow">return</span> <span class="keyword">true</span>;<a name="l00081"></a>00081 <span class="keywordflow">case</span> 2:<a name="l00082"></a>00082 <span class="keywordflow">case</span> 3:<a name="l00083"></a>00083 {<a name="l00084"></a>00084 <span class="keywordflow">if</span> (encodedPointLen != <a class="code" href="class_e_c_p.html#4273ed51110725435ddeefcac166c29d">EncodedPointSize</a>(<span class="keyword">true</span>))<a name="l00085"></a>00085 <span class="keywordflow">return</span> <span class="keyword">false</span>;<a name="l00086"></a>00086 <a name="l00087"></a>00087 <a class="code" href="class_integer.html" title="multiple precision integer and basic arithmetics">Integer</a> p = <a class="code" href="class_e_c_p.html#b0c01cf1ebf788ba647fb8a076c6dcee">FieldSize</a>();<a name="l00088"></a>00088 <a name="l00089"></a>00089 P.<a class="code" href="struct_e_c_p_point.html#806dedcf077e22de7904ccfd7987bcf9">identity</a> = <span class="keyword">false</span>;<a name="l00090"></a>00090 P.<a class="code" href="struct_e_c_p_point.html#24bbcc7eb375ebe2b46d2ac9ee6bb0a8">x</a>.<a class="code" href="class_integer.html#e91fee9e9873f3412f47e6d647545099">Decode</a>(bt, <a class="code" href="class_e_c_p.html#e996fce212244df79b83a587317f7423">GetField</a>().MaxElementByteLength()); <a name="l00091"></a>00091 P.<a class="code" href="struct_e_c_p_point.html#b47b82046f543e809bd90d78bf2c85bf">y</a> = ((P.<a class="code" href="struct_e_c_p_point.html#24bbcc7eb375ebe2b46d2ac9ee6bb0a8">x</a>*P.<a class="code" href="struct_e_c_p_point.html#24bbcc7eb375ebe2b46d2ac9ee6bb0a8">x</a>+m_a)*P.<a class="code" href="struct_e_c_p_point.html#24bbcc7eb375ebe2b46d2ac9ee6bb0a8">x</a>+m_b) % p;<a name="l00092"></a>00092 <a name="l00093"></a>00093 <span class="keywordflow">if</span> (Jacobi(P.<a class="code" href="struct_e_c_p_point.html#b47b82046f543e809bd90d78bf2c85bf">y</a>, p) !=1)<a name="l00094"></a>00094 <span class="keywordflow">return</span> <span class="keyword">false</span>;<a name="l00095"></a>00095 <a name="l00096"></a>00096 P.<a class="code" href="struct_e_c_p_point.html#b47b82046f543e809bd90d78bf2c85bf">y</a> = ModularSquareRoot(P.<a class="code" href="struct_e_c_p_point.html#b47b82046f543e809bd90d78bf2c85bf">y</a>, p);<a name="l00097"></a>00097 <a name="l00098"></a>00098 <span class="keywordflow">if</span> ((type & 1) != P.<a class="code" href="struct_e_c_p_point.html#b47b82046f543e809bd90d78bf2c85bf">y</a>.<a class="code" href="class_integer.html#0e377d23bde55fc7dc6ea2208c587d19" title="return the i-th bit, i=0 being the least significant bit">GetBit</a>(0))<a name="l00099"></a>00099 P.<a class="code" href="struct_e_c_p_point.html#b47b82046f543e809bd90d78bf2c85bf">y</a> = p-P.<a class="code" href="struct_e_c_p_point.html#b47b82046f543e809bd90d78bf2c85bf">y</a>;<a name="l00100"></a>00100 <a name="l00101"></a>00101 <span class="keywordflow">return</span> <span class="keyword">true</span>;<a name="l00102"></a>00102 }<a name="l00103"></a>00103 <span class="keywordflow">case</span> 4:<a name="l00104"></a>00104 {⌨️ 快捷键说明
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