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<hr><h1>sapphire.cpp</h1><div class="fragment"><pre>00001 <font class="comment">/* sapphire.cpp -- the Saphire II stream cipher class.</font>
00002 <font class="comment"> Dedicated to the Public Domain the author and inventor:</font>
00003 <font class="comment"> (Michael Paul Johnson). This code comes with no warranty.</font>
00004 <font class="comment"> Use it at your own risk.</font>
00005 <font class="comment"> Ported from the Pascal implementation of the Sapphire Stream</font>
00006 <font class="comment"> Cipher 9 December 1994.</font>
00007 <font class="comment"> Added hash pre- and post-processing 27 December 1994.</font>
00008 <font class="comment"> Modified initialization to make index variables key dependent,</font>
00009 <font class="comment"> made the output function more resistant to cryptanalysis,</font>
00010 <font class="comment"> and renamed to Sapphire II 2 January 1995</font>
00011 <font class="comment">*/</font>
00012
00013
00014 <font class="preprocessor">#ifdef WIN32</font>
00015 <font class="preprocessor"></font><font class="preprocessor">#include <memory.h></font>
00016 <font class="preprocessor">#endif</font>
00017 <font class="preprocessor"></font>
00018 <font class="preprocessor">#ifdef UNIX</font>
00019 <font class="preprocessor"></font><font class="preprocessor">#include <memory.h></font>
00020 <font class="preprocessor">#include <unistd.h></font>
00021 <font class="preprocessor">#else</font>
00022 <font class="preprocessor"></font><font class="preprocessor">#ifndef _MSC_VER</font>
00023 <font class="preprocessor"></font><font class="preprocessor">#include <mem.h></font>
00024 <font class="preprocessor">#endif</font>
00025 <font class="preprocessor"></font><font class="preprocessor">#endif</font>
00026 <font class="preprocessor"></font>
00027 <font class="preprocessor">#ifdef _WIN32_WCE</font>
00028 <font class="preprocessor"></font><font class="preprocessor">#include <string.h></font>
00029 <font class="preprocessor">#endif</font>
00030 <font class="preprocessor"></font>
00031 <font class="preprocessor">#include "sapphire.h"</font>
00032
00033 <font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> sapphire::keyrand(<font class="keywordtype">int</font> limit,
00034 <font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> *user_key,
00035 <font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> keysize,
00036 <font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> *rsum,
00037 <font class="keywordtype">unsigned</font> *keypos)
00038 {
00039 <font class="keywordtype">unsigned</font> u, <font class="comment">// Value from 0 to limit to return.</font>
00040 retry_limiter, <font class="comment">// No infinite loops allowed.</font>
00041 mask; <font class="comment">// Select just enough bits.</font>
00042
00043 <font class="keywordflow">if</font> (!limit) <font class="keywordflow">return</font> 0; <font class="comment">// Avoid divide by zero error.</font>
00044 retry_limiter = 0;
00045 mask = 1; <font class="comment">// Fill mask with enough bits to cover</font>
00046 <font class="keywordflow">while</font> (mask < (unsigned)limit) <font class="comment">// the desired range.</font>
00047 mask = (mask << 1) + 1;
00048 <font class="keywordflow">do</font>
00049 {
00050 *rsum = cards[*rsum] + user_key[(*keypos)++];
00051 <font class="keywordflow">if</font> (*keypos >= keysize)
00052 {
00053 *keypos = 0; <font class="comment">// Recycle the user key.</font>
00054 *rsum += keysize; <font class="comment">// key "aaaa" != key "aaaaaaaa"</font>
00055 }
00056 u = mask & *rsum;
00057 <font class="keywordflow">if</font> (++retry_limiter > 11)
00058 u %= limit; <font class="comment">// Prevent very rare long loops.</font>
00059 }
00060 <font class="keywordflow">while</font> (u > (unsigned)limit);
00061 <font class="keywordflow">return</font> u;
00062 }
00063
00064 <font class="keywordtype">void</font> sapphire::initialize(<font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> *key, <font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> keysize)
00065 {
00066 <font class="comment">// Key size may be up to 256 bytes.</font>
00067 <font class="comment">// Pass phrases may be used directly, with longer length</font>
00068 <font class="comment">// compensating for the low entropy expected in such keys.</font>
00069 <font class="comment">// Alternatively, shorter keys hashed from a pass phrase or</font>
00070 <font class="comment">// generated randomly may be used. For random keys, lengths</font>
00071 <font class="comment">// of from 4 to 16 bytes are recommended, depending on how</font>
00072 <font class="comment">// secure you want this to be.</font>
00073
00074 <font class="keywordtype">int</font> i;
00075 <font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> toswap, swaptemp, rsum;
00076 <font class="keywordtype">unsigned</font> keypos;
00077
00078 <font class="comment">// If we have been given no key, assume the default hash setup.</font>
00079
00080 <font class="keywordflow">if</font> (keysize < 1)
00081 {
00082 hash_init();
00083 <font class="keywordflow">return</font>;
00084 }
00085
00086 <font class="comment">// Start with cards all in order, one of each.</font>
00087
00088 <font class="keywordflow">for</font> (i=0;i<256;i++)
00089 cards[i] = i;
00090
00091 <font class="comment">// Swap the card at each position with some other card.</font>
00092
00093 toswap = 0;
00094 keypos = 0; <font class="comment">// Start with first byte of user key.</font>
00095 rsum = 0;
00096 <font class="keywordflow">for</font> (i=255;i>=0;i--)
00097 {
00098 toswap = keyrand(i, key, keysize, &rsum, &keypos);
00099 swaptemp = cards[i];
00100 cards[i] = cards[toswap];
00101 cards[toswap] = swaptemp;
00102 }
00103
00104 <font class="comment">// Initialize the indices and data dependencies.</font>
00105 <font class="comment">// Indices are set to different values instead of all 0</font>
00106 <font class="comment">// to reduce what is known about the state of the cards</font>
00107 <font class="comment">// when the first byte is emitted.</font>
00108
00109 rotor = cards[1];
00110 ratchet = cards[3];
00111 avalanche = cards[5];
00112 last_plain = cards[7];
00113 last_cipher = cards[rsum];
00114
00115 toswap = swaptemp = rsum = 0;
00116 keypos = 0;
00117 }
00118
00119 <font class="keywordtype">void</font> sapphire::hash_init(<font class="keywordtype">void</font>)
00120 {
00121 <font class="comment">// This function is used to initialize non-keyed hash</font>
00122 <font class="comment">// computation.</font>
00123
00124 <font class="keywordtype">int</font> i, j;
00125
00126 <font class="comment">// Initialize the indices and data dependencies.</font>
00127
00128 rotor = 1;
00129 ratchet = 3;
00130 avalanche = 5;
00131 last_plain = 7;
00132 last_cipher = 11;
00133
00134 <font class="comment">// Start with cards all in inverse order.</font>
00135
00136 <font class="keywordflow">for</font> (i=0, j=255;i<256;i++,j--)
00137 cards[i] = (<font class="keywordtype">unsigned</font> <font class="keywordtype">char</font>) j;
00138 }
00139
00140 sapphire::sapphire(<font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> *key, <font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> keysize)
00141 {
00142 <font class="keywordflow">if</font> (key && keysize)
00143 initialize(key, keysize);
00144 }
00145
00146 <font class="keywordtype">void</font> sapphire::burn(<font class="keywordtype">void</font>)
00147 {
00148 <font class="comment">// Destroy the key and state information in RAM.</font>
00149 memset(cards, 0, 256);
00150 rotor = ratchet = avalanche = last_plain = last_cipher = 0;
00151 }
00152
00153 sapphire::~sapphire()
00154 {
00155 burn();
00156 }
00157
00158 <font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> sapphire::encrypt(<font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> b)
00159 {
00160 <font class="preprocessor">#ifdef USBINARY</font>
00161 <font class="preprocessor"></font> <font class="comment">// Picture a single enigma rotor with 256 positions, rewired</font>
00162 <font class="comment">// on the fly by card-shuffling.</font>
00163
00164 <font class="comment">// This cipher is a variant of one invented and written</font>
00165 <font class="comment">// by Michael Paul Johnson in November, 1993.</font>
00166
00167 <font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> swaptemp;
00168
00169 <font class="comment">// Shuffle the deck a little more.</font>
00170
00171 ratchet += cards[rotor++];
00172 swaptemp = cards[last_cipher];
00173 cards[last_cipher] = cards[ratchet];
00174 cards[ratchet] = cards[last_plain];
00175 cards[last_plain] = cards[rotor];
00176 cards[rotor] = swaptemp;
00177 avalanche += cards[swaptemp];
00178
00179 <font class="comment">// Output one byte from the state in such a way as to make it</font>
00180 <font class="comment">// very hard to figure out which one you are looking at.</font>
00181
00182 last_cipher = b^cards[(cards[ratchet] + cards[rotor]) & 0xFF] ^
00183 cards[cards[(cards[last_plain] +
00184 cards[last_cipher] +
00185 cards[avalanche])&0xFF]];
00186 last_plain = b;
00187 <font class="keywordflow">return</font> last_cipher;
00188 <font class="preprocessor">#else</font>
00189 <font class="preprocessor"></font> <font class="keywordflow">return</font> b;
00190 <font class="preprocessor">#endif</font>
00191 <font class="preprocessor"></font> }
00192
00193 <font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> sapphire::decrypt(<font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> b)
00194 {
00195 <font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> swaptemp;
00196
00197 <font class="comment">// Shuffle the deck a little more.</font>
00198
00199 ratchet += cards[rotor++];
00200 swaptemp = cards[last_cipher];
00201 cards[last_cipher] = cards[ratchet];
00202 cards[ratchet] = cards[last_plain];
00203 cards[last_plain] = cards[rotor];
00204 cards[rotor] = swaptemp;
00205 avalanche += cards[swaptemp];
00206
00207 <font class="comment">// Output one byte from the state in such a way as to make it</font>
00208 <font class="comment">// very hard to figure out which one you are looking at.</font>
00209
00210 last_plain = b^cards[(cards[ratchet] + cards[rotor]) & 0xFF] ^
00211 cards[cards[(cards[last_plain] +
00212 cards[last_cipher] +
00213 cards[avalanche])&0xFF]];
00214 last_cipher = b;
00215 <font class="keywordflow">return</font> last_plain;
00216 }
00217
00218 <font class="keywordtype">void</font> sapphire::hash_final(<font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> *hash, <font class="comment">// Destination</font>
00219 <font class="keywordtype">unsigned</font> <font class="keywordtype">char</font> hashlength) <font class="comment">// Size of hash.</font>
00220 {
00221 <font class="keywordtype">int</font> i;
00222
00223 <font class="keywordflow">for</font> (i=255;i>=0;i--)
00224 encrypt((<font class="keywordtype">unsigned</font> <font class="keywordtype">char</font>) i);
00225 <font class="keywordflow">for</font> (i=0;i<hashlength;i++)
00226 hash[i] = encrypt(0);
00227 }
00228
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