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mars.cpp

00001 // mars.cpp - modified by Sean Woods from Brian Gladman's mars6.c for Crypto++ 00002 // key setup updated by Wei Dai to reflect IBM's "tweak" proposed in August 1999 00003 00004 /* This is an independent implementation of the MARS encryption */ 00005 /* algorithm designed by a team at IBM as a candidate for the US */ 00006 /* NIST Advanced Encryption Standard (AES) effort. The algorithm */ 00007 /* is subject to Patent action by IBM, who intend to offer royalty */ 00008 /* free use if a Patent is granted. */ 00009 /* */ 00010 /* Copyright in this implementation is held by Dr B R Gladman but */ 00011 /* I hereby give permission for its free direct or derivative use */ 00012 /* subject to acknowledgment of its origin and compliance with any */ 00013 /* constraints that IBM place on the use of the MARS algorithm. */ 00014 /* */ 00015 /* Dr Brian Gladman (gladman@seven77.demon.co.uk) 4th October 1998 */ 00016 00017 #include "pch.h" 00018 #include "mars.h" 00019 #include "misc.h" 00020 00021 NAMESPACE_BEGIN(CryptoPP) 00022 00023 ANONYMOUS_NAMESPACE_BEGIN 00024 static word32 gen_mask(word32 x) 00025 { 00026 word32 m; 00027 00028 m = (~x ^ (x >> 1)) & 0x7fffffff; 00029 m &= (m >> 1) & (m >> 2); m &= (m >> 3) & (m >> 6); 00030 00031 if(!m) 00032 return 0; 00033 00034 m <<= 1; m |= (m << 1); m |= (m << 2); m |= (m << 4); 00035 m |= (m << 1) & ~x & 0x80000000; 00036 00037 return m & 0xfffffffc; 00038 }; 00039 NAMESPACE_END 00040 00041 void MARS::Base::UncheckedSetKey(CipherDir direction, const byte *userKey, unsigned int length) 00042 { 00043 AssertValidKeyLength(length); 00044 00045 // Initialize T[] with the key data 00046 FixedSizeSecBlock<word32, 15> T; 00047 GetUserKey(LITTLE_ENDIAN_ORDER, T.begin(), 15, userKey, length); 00048 T[length/4] = length/4; 00049 00050 for (unsigned int j=0; j<4; j++) // compute 10 words of K[] in each iteration 00051 { 00052 unsigned int i; 00053 // Do linear transformation 00054 for (i=0; i<15; i++) 00055 T[i] = T[i] ^ rotlFixed(T[(i+8)%15] ^ T[(i+13)%15], 3) ^ (4*i+j); 00056 00057 // Do four rounds of stirring 00058 for (unsigned int k=0; k<4; k++) 00059 for (i=0; i<15; i++) 00060 T[i] = rotlFixed(T[i] + Sbox[T[(i+14)%15]%512], 9); 00061 00062 // Store next 10 key words into K[] 00063 for (i=0; i<10; i++) 00064 EK[10*j+i] = T[4*i%15]; 00065 } 00066 00067 // Modify multiplication key-words 00068 for(unsigned int i = 5; i < 37; i += 2) 00069 { 00070 word32 w = EK[i] | 3; 00071 word32 m = gen_mask(w); 00072 if(m) 00073 w ^= (rotlMod(Sbox[265 + (EK[i] & 3)], EK[i-1]) & m); 00074 EK[i] = w; 00075 } 00076 } 00077 00078 #define f_mix(a,b,c,d) \ 00079 r = rotrFixed(a, 8); \ 00080 b ^= Sbox[a & 255]; \ 00081 b += Sbox[(r & 255) + 256]; \ 00082 r = rotrFixed(a, 16); \ 00083 a = rotrFixed(a, 24); \ 00084 c += Sbox[r & 255]; \ 00085 d ^= Sbox[(a & 255) + 256] 00086 00087 #define b_mix(a,b,c,d) \ 00088 r = rotlFixed(a, 8); \ 00089 b ^= Sbox[(a & 255) + 256]; \ 00090 c -= Sbox[r & 255]; \ 00091 r = rotlFixed(a, 16); \ 00092 a = rotlFixed(a, 24); \ 00093 d -= Sbox[(r & 255) + 256]; \ 00094 d ^= Sbox[a & 255] 00095 00096 #define f_ktr(a,b,c,d,i) \ 00097 m = a + EK[i]; \ 00098 a = rotlFixed(a, 13); \ 00099 r = a * EK[i + 1]; \ 00100 l = Sbox[m & 511]; \ 00101 r = rotlFixed(r, 5); \ 00102 l ^= r; \ 00103 c += rotlMod(m, r); \ 00104 r = rotlFixed(r, 5); \ 00105 l ^= r; \ 00106 d ^= r; \ 00107 b += rotlMod(l, r) 00108 00109 #define r_ktr(a,b,c,d,i) \ 00110 r = a * EK[i + 1]; \ 00111 a = rotrFixed(a, 13); \ 00112 m = a + EK[i]; \ 00113 l = Sbox[m & 511]; \ 00114 r = rotlFixed(r, 5); \ 00115 l ^= r; \ 00116 c -= rotlMod(m, r); \ 00117 r = rotlFixed(r, 5); \ 00118 l ^= r; \ 00119 d ^= r; \ 00120 b -= rotlMod(l, r) 00121 00122 typedef BlockGetAndPut<word32, LittleEndian> Block; 00123 00124 void MARS::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const 00125 { 00126 word32 a, b, c, d, l, m, r; 00127 00128 Block::Get(inBlock)(a)(b)(c)(d); 00129 00130 a += EK[0]; 00131 b += EK[1]; 00132 c += EK[2]; 00133 d += EK[3]; 00134 00135 int i; 00136 for (i = 0; i < 2; i++) { 00137 f_mix(a,b,c,d); 00138 a += d; 00139 f_mix(b,c,d,a); 00140 b += c; 00141 f_mix(c,d,a,b); 00142 f_mix(d,a,b,c); 00143 } 00144 00145 f_ktr(a,b,c,d, 4); f_ktr(b,c,d,a, 6); f_ktr(c,d,a,b, 8); f_ktr(d,a,b,c,10); 00146 f_ktr(a,b,c,d,12); f_ktr(b,c,d,a,14); f_ktr(c,d,a,b,16); f_ktr(d,a,b,c,18); 00147 f_ktr(a,d,c,b,20); f_ktr(b,a,d,c,22); f_ktr(c,b,a,d,24); f_ktr(d,c,b,a,26); 00148 f_ktr(a,d,c,b,28); f_ktr(b,a,d,c,30); f_ktr(c,b,a,d,32); f_ktr(d,c,b,a,34); 00149 00150 for (i = 0; i < 2; i++) { 00151 b_mix(a,b,c,d); 00152 b_mix(b,c,d,a); 00153 c -= b; 00154 b_mix(c,d,a,b); 00155 d -= a; 00156 b_mix(d,a,b,c); 00157 } 00158 00159 a -= EK[36]; 00160 b -= EK[37]; 00161 c -= EK[38]; 00162 d -= EK[39]; 00163 00164 Block::Put(xorBlock, outBlock)(a)(b)(c)(d); 00165 } 00166 00167 void MARS::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const 00168 { 00169 word32 a, b, c, d, l, m, r; 00170 00171 Block::Get(inBlock)(d)(c)(b)(a); 00172 00173 d += EK[36]; 00174 c += EK[37]; 00175 b += EK[38]; 00176 a += EK[39]; 00177 00178 int i; 00179 for (i = 0; i < 2; i++) { 00180 f_mix(a,b,c,d); 00181 a += d; 00182 f_mix(b,c,d,a); 00183 b += c; 00184 f_mix(c,d,a,b); 00185 f_mix(d,a,b,c); 00186 } 00187 00188 r_ktr(a,b,c,d,34); r_ktr(b,c,d,a,32); r_ktr(c,d,a,b,30); r_ktr(d,a,b,c,28); 00189 r_ktr(a,b,c,d,26); r_ktr(b,c,d,a,24); r_ktr(c,d,a,b,22); r_ktr(d,a,b,c,20); 00190 r_ktr(a,d,c,b,18); r_ktr(b,a,d,c,16); r_ktr(c,b,a,d,14); r_ktr(d,c,b,a,12); 00191 r_ktr(a,d,c,b,10); r_ktr(b,a,d,c, 8); r_ktr(c,b,a,d, 6); r_ktr(d,c,b,a, 4); 00192 00193 for (i = 0; i < 2; i++) { 00194 b_mix(a,b,c,d); 00195 b_mix(b,c,d,a); 00196 c -= b; 00197 b_mix(c,d,a,b); 00198 d -= a; 00199 b_mix(d,a,b,c); 00200 } 00201 00202 d -= EK[0]; 00203 c -= EK[1]; 00204 b -= EK[2]; 00205 a -= EK[3]; 00206 00207 Block::Put(xorBlock, outBlock)(d)(c)(b)(a); 00208 } 00209 00210 NAMESPACE_END

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