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<h1>cmac.cpp</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">// cmac.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 "cmac.h"</span>
<a name="l00008"></a>00008
<a name="l00009"></a>00009 NAMESPACE_BEGIN(CryptoPP)
<a name="l00010"></a>00010
<a name="l00011"></a>00011 static <span class="keywordtype">void</span> MulU(byte *k, <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> length)
<a name="l00012"></a>00012 {
<a name="l00013"></a>00013 byte carry = 0;
<a name="l00014"></a>00014
<a name="l00015"></a>00015 <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i=length-1; i>=1; i-=2)
<a name="l00016"></a>00016 {
<a name="l00017"></a>00017 byte carry2 = k[i] >> 7;
<a name="l00018"></a>00018 k[i] += k[i] + carry;
<a name="l00019"></a>00019 carry = k[i-1] >> 7;
<a name="l00020"></a>00020 k[i-1] += k[i-1] + carry2;
<a name="l00021"></a>00021 }
<a name="l00022"></a>00022
<a name="l00023"></a>00023 <span class="keywordflow">if</span> (carry)
<a name="l00024"></a>00024 {
<a name="l00025"></a>00025 <span class="keywordflow">switch</span> (length)
<a name="l00026"></a>00026 {
<a name="l00027"></a>00027 <span class="keywordflow">case</span> 8:
<a name="l00028"></a>00028 k[7] ^= 0x1b;
<a name="l00029"></a>00029 <span class="keywordflow">break</span>;
<a name="l00030"></a>00030 <span class="keywordflow">case</span> 16:
<a name="l00031"></a>00031 k[15] ^= 0x87;
<a name="l00032"></a>00032 <span class="keywordflow">break</span>;
<a name="l00033"></a>00033 <span class="keywordflow">case</span> 32:
<a name="l00034"></a>00034 k[30] ^= 4;
<a name="l00035"></a>00035 k[31] ^= 0x23;
<a name="l00036"></a>00036 <span class="keywordflow">break</span>;
<a name="l00037"></a>00037 <span class="keywordflow">default</span>:
<a name="l00038"></a>00038 <span class="keywordflow">throw</span> <a class="code" href="class_invalid_argument.html" title="exception thrown when an invalid argument is detected">InvalidArgument</a>(<span class="stringliteral">"CMAC: "</span> + IntToString(length) + <span class="stringliteral">" is not a supported cipher block size"</span>);
<a name="l00039"></a>00039 }
<a name="l00040"></a>00040 }
<a name="l00041"></a>00041 }
<a name="l00042"></a>00042
<a name="l00043"></a>00043 <span class="keywordtype">void</span> CMAC_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" title="interface for retrieving values given their names">NameValuePairs</a> &params)
<a name="l00044"></a>00044 {
<a name="l00045"></a>00045 <a class="code" href="class_block_cipher.html" title="interface for one direction (encryption or decryption) of a block cipher">BlockCipher</a> &cipher = AccessCipher();
<a name="l00046"></a>00046 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> blockSize = cipher.<a class="code" href="class_block_transformation.html#adfdb78b033996020435c3dcffdca76ce" title="block size of the cipher in bytes">BlockSize</a>();
<a name="l00047"></a>00047
<a name="l00048"></a>00048 cipher.<a class="code" href="class_simple_keying_interface.html#adf3c29b3ef3af74788a58c7c49887fd7" title="set or reset the key of this object">SetKey</a>(key, length, params);
<a name="l00049"></a>00049 m_reg.<a class="code" href="class_sec_block.html#a2d78e75002fd02e5b89bd72a9e65e769" title="change size and set contents to 0">CleanNew</a>(3*blockSize);
<a name="l00050"></a>00050 m_counter = 0;
<a name="l00051"></a>00051
<a name="l00052"></a>00052 cipher.<a class="code" href="class_block_transformation.html#a2fefb3f4c6c6297c0c91fcbba9e4f4f3" title="encrypt or decrypt one block">ProcessBlock</a>(m_reg, m_reg+blockSize);
<a name="l00053"></a>00053 MulU(m_reg+blockSize, blockSize);
<a name="l00054"></a>00054 memcpy(m_reg+2*blockSize, m_reg+blockSize, blockSize);
<a name="l00055"></a>00055 MulU(m_reg+2*blockSize, blockSize);
<a name="l00056"></a>00056 }
<a name="l00057"></a>00057
<a name="l00058"></a><a class="code" href="class_c_m_a_c___base.html#a582cd6d32b41c65d10481ebcd2c1aed4">00058</a> <span class="keywordtype">void</span> <a class="code" href="class_c_m_a_c___base.html#a582cd6d32b41c65d10481ebcd2c1aed4" title="process more input">CMAC_Base::Update</a>(<span class="keyword">const</span> byte *input, <span class="keywordtype">size_t</span> length)
<a name="l00059"></a>00059 {
<a name="l00060"></a>00060 <span class="keywordflow">if</span> (!length)
<a name="l00061"></a>00061 <span class="keywordflow">return</span>;
<a name="l00062"></a>00062
<a name="l00063"></a>00063 <a class="code" href="class_block_cipher.html" title="interface for one direction (encryption or decryption) of a block cipher">BlockCipher</a> &cipher = AccessCipher();
<a name="l00064"></a>00064 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> blockSize = cipher.<a class="code" href="class_block_transformation.html#adfdb78b033996020435c3dcffdca76ce" title="block size of the cipher in bytes">BlockSize</a>();
<a name="l00065"></a>00065
<a name="l00066"></a>00066 <span class="keywordflow">if</span> (m_counter > 0)
<a name="l00067"></a>00067 {
<a name="l00068"></a>00068 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> len = UnsignedMin(blockSize - m_counter, length);
<a name="l00069"></a>00069 xorbuf(m_reg+m_counter, input, len);
<a name="l00070"></a>00070 length -= len;
<a name="l00071"></a>00071 input += len;
<a name="l00072"></a>00072 m_counter += len;
<a name="l00073"></a>00073
<a name="l00074"></a>00074 <span class="keywordflow">if</span> (m_counter == blockSize && length > 0)
<a name="l00075"></a>00075 {
<a name="l00076"></a>00076 cipher.<a class="code" href="class_block_transformation.html#a2fefb3f4c6c6297c0c91fcbba9e4f4f3" title="encrypt or decrypt one block">ProcessBlock</a>(m_reg);
<a name="l00077"></a>00077 m_counter = 0;
<a name="l00078"></a>00078 }
<a name="l00079"></a>00079 }
<a name="l00080"></a>00080
<a name="l00081"></a>00081 <span class="keywordflow">if</span> (length > blockSize)
<a name="l00082"></a>00082 {
<a name="l00083"></a>00083 assert(m_counter == 0);
<a name="l00084"></a>00084 <span class="keywordtype">size_t</span> leftOver = 1 + cipher.<a class="code" href="class_block_transformation.html#adcff119bb709c84bfaaab8d1871b018c" title="encrypt and xor blocks according to flags (see FlagsForAdvancedProcessBlocks)">AdvancedProcessBlocks</a>(m_reg, input, m_reg, length-1, BlockTransformation::BT_DontIncrementInOutPointers|BlockTransformation::BT_XorInput);
<a name="l00085"></a>00085 input += (length - leftOver);
<a name="l00086"></a>00086 length = leftOver;
<a name="l00087"></a>00087 }
<a name="l00088"></a>00088
<a name="l00089"></a>00089 <span class="keywordflow">if</span> (length > 0)
<a name="l00090"></a>00090 {
<a name="l00091"></a>00091 assert(m_counter + length <= blockSize);
<a name="l00092"></a>00092 xorbuf(m_reg+m_counter, input, length);
<a name="l00093"></a>00093 m_counter += (<span class="keywordtype">unsigned</span> int)length;
<a name="l00094"></a>00094 }
<a name="l00095"></a>00095
<a name="l00096"></a>00096 assert(m_counter > 0);
<a name="l00097"></a>00097 }
<a name="l00098"></a>00098
<a name="l00099"></a><a class="code" href="class_c_m_a_c___base.html#a636b8a77c098bb08955ec8b4e66448a7">00099</a> <span class="keywordtype">void</span> <a class="code" href="class_c_m_a_c___base.html#a636b8a77c098bb08955ec8b4e66448a7" title="truncated version of Final()">CMAC_Base::TruncatedFinal</a>(byte *mac, <span class="keywordtype">size_t</span> size)
<a name="l00100"></a>00100 {
<a name="l00101"></a>00101 ThrowIfInvalidTruncatedSize(size);
<a name="l00102"></a>00102
<a name="l00103"></a>00103 <a class="code" href="class_block_cipher.html" title="interface for one direction (encryption or decryption) of a block cipher">BlockCipher</a> &cipher = AccessCipher();
<a name="l00104"></a>00104 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> blockSize = cipher.<a class="code" href="class_block_transformation.html#adfdb78b033996020435c3dcffdca76ce" title="block size of the cipher in bytes">BlockSize</a>();
<a name="l00105"></a>00105
<a name="l00106"></a>00106 <span class="keywordflow">if</span> (m_counter < blockSize)
<a name="l00107"></a>00107 {
<a name="l00108"></a>00108 m_reg[m_counter] ^= 0x80;
<a name="l00109"></a>00109 cipher.<a class="code" href="class_block_transformation.html#adcff119bb709c84bfaaab8d1871b018c" title="encrypt and xor blocks according to flags (see FlagsForAdvancedProcessBlocks)">AdvancedProcessBlocks</a>(m_reg, m_reg+2*blockSize, m_reg, blockSize, BlockTransformation::BT_DontIncrementInOutPointers|BlockTransformation::BT_XorInput);
<a name="l00110"></a>00110 }
<a name="l00111"></a>00111 <span class="keywordflow">else</span>
<a name="l00112"></a>00112 cipher.<a class="code" href="class_block_transformation.html#adcff119bb709c84bfaaab8d1871b018c" title="encrypt and xor blocks according to flags (see FlagsForAdvancedProcessBlocks)">AdvancedProcessBlocks</a>(m_reg, m_reg+blockSize, m_reg, blockSize, BlockTransformation::BT_DontIncrementInOutPointers|BlockTransformation::BT_XorInput);
<a name="l00113"></a>00113
<a name="l00114"></a>00114 memcpy(mac, m_reg, size);
<a name="l00115"></a>00115
<a name="l00116"></a>00116 m_counter = 0;
<a name="l00117"></a>00117 memset(m_reg, 0, blockSize);
<a name="l00118"></a>00118 }
<a name="l00119"></a>00119
<a name="l00120"></a>00120 NAMESPACE_END
<a name="l00121"></a>00121
<a name="l00122"></a>00122 <span class="preprocessor">#endif</span>
</pre></div></div>
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