release/src/router/libsodium/src/libsodium/crypto_sign/ed25519/ref10/sc_reduce.c

   1 #include "sc.h"
   2 #include "crypto_int64.h"
   3 #include "crypto_uint32.h"
   4 #include "crypto_uint64.h"
   5
   6 static crypto_uint64 load_3(const unsigned char *in)
   7 {
   8   crypto_uint64 result;
   9   result = (crypto_uint64) in[0];
  10   result |= ((crypto_uint64) in[1]) << 8;
  11   result |= ((crypto_uint64) in[2]) << 16;
  12   return result;
  13 }
  14
  15 static crypto_uint64 load_4(const unsigned char *in)
  16 {
  17   crypto_uint64 result;
  18   result = (crypto_uint64) in[0];
  19   result |= ((crypto_uint64) in[1]) << 8;
  20   result |= ((crypto_uint64) in[2]) << 16;
  21   result |= ((crypto_uint64) in[3]) << 24;
  22   return result;
  23 }
  24
  25 /*
  26 Input:
  27   s[0]+256*s[1]+...+256^63*s[63] = s
  28
  29 Output:
  30   s[0]+256*s[1]+...+256^31*s[31] = s mod l
  31   where l = 2^252 + 27742317777372353535851937790883648493.
  32   Overwrites s in place.
  33 */
  34
  35 void sc_reduce(unsigned char *s)
  36 {
  37   crypto_int64 s0 = 2097151 & load_3(s);
  38   crypto_int64 s1 = 2097151 & (load_4(s + 2) >> 5);
  39   crypto_int64 s2 = 2097151 & (load_3(s + 5) >> 2);
  40   crypto_int64 s3 = 2097151 & (load_4(s + 7) >> 7);
  41   crypto_int64 s4 = 2097151 & (load_4(s + 10) >> 4);
  42   crypto_int64 s5 = 2097151 & (load_3(s + 13) >> 1);
  43   crypto_int64 s6 = 2097151 & (load_4(s + 15) >> 6);
  44   crypto_int64 s7 = 2097151 & (load_3(s + 18) >> 3);
  45   crypto_int64 s8 = 2097151 & load_3(s + 21);
  46   crypto_int64 s9 = 2097151 & (load_4(s + 23) >> 5);
  47   crypto_int64 s10 = 2097151 & (load_3(s + 26) >> 2);
  48   crypto_int64 s11 = 2097151 & (load_4(s + 28) >> 7);
  49   crypto_int64 s12 = 2097151 & (load_4(s + 31) >> 4);
  50   crypto_int64 s13 = 2097151 & (load_3(s + 34) >> 1);
  51   crypto_int64 s14 = 2097151 & (load_4(s + 36) >> 6);
  52   crypto_int64 s15 = 2097151 & (load_3(s + 39) >> 3);
  53   crypto_int64 s16 = 2097151 & load_3(s + 42);
  54   crypto_int64 s17 = 2097151 & (load_4(s + 44) >> 5);
  55   crypto_int64 s18 = 2097151 & (load_3(s + 47) >> 2);
  56   crypto_int64 s19 = 2097151 & (load_4(s + 49) >> 7);
  57   crypto_int64 s20 = 2097151 & (load_4(s + 52) >> 4);
  58   crypto_int64 s21 = 2097151 & (load_3(s + 55) >> 1);
  59   crypto_int64 s22 = 2097151 & (load_4(s + 57) >> 6);
  60   crypto_int64 s23 = (load_4(s + 60) >> 3);
  61   crypto_int64 carry0;
  62   crypto_int64 carry1;
  63   crypto_int64 carry2;
  64   crypto_int64 carry3;
  65   crypto_int64 carry4;
  66   crypto_int64 carry5;
  67   crypto_int64 carry6;
  68   crypto_int64 carry7;
  69   crypto_int64 carry8;
  70   crypto_int64 carry9;
  71   crypto_int64 carry10;
  72   crypto_int64 carry11;
  73   crypto_int64 carry12;
  74   crypto_int64 carry13;
  75   crypto_int64 carry14;
  76   crypto_int64 carry15;
  77   crypto_int64 carry16;
  78
  79   s11 += s23 * 666643;
  80   s12 += s23 * 470296;
  81   s13 += s23 * 654183;
  82   s14 -= s23 * 997805;
  83   s15 += s23 * 136657;
  84   s16 -= s23 * 683901;
  85   s23 = 0;
  86
  87   s10 += s22 * 666643;
  88   s11 += s22 * 470296;
  89   s12 += s22 * 654183;
  90   s13 -= s22 * 997805;
  91   s14 += s22 * 136657;
  92   s15 -= s22 * 683901;
  93   s22 = 0;
  94
  95   s9 += s21 * 666643;
  96   s10 += s21 * 470296;
  97   s11 += s21 * 654183;
  98   s12 -= s21 * 997805;
  99   s13 += s21 * 136657;
 100   s14 -= s21 * 683901;
 101   s21 = 0;
 102
 103   s8 += s20 * 666643;
 104   s9 += s20 * 470296;
 105   s10 += s20 * 654183;
 106   s11 -= s20 * 997805;
 107   s12 += s20 * 136657;
 108   s13 -= s20 * 683901;
 109   s20 = 0;
 110
 111   s7 += s19 * 666643;
 112   s8 += s19 * 470296;
 113   s9 += s19 * 654183;
 114   s10 -= s19 * 997805;
 115   s11 += s19 * 136657;
 116   s12 -= s19 * 683901;
 117   s19 = 0;
 118
 119   s6 += s18 * 666643;
 120   s7 += s18 * 470296;
 121   s8 += s18 * 654183;
 122   s9 -= s18 * 997805;
 123   s10 += s18 * 136657;
 124   s11 -= s18 * 683901;
 125   s18 = 0;
 126
 127   carry6 = (s6 + (1<<20)) >> 21; s7 += carry6; s6 -= carry6 << 21;
 128   carry8 = (s8 + (1<<20)) >> 21; s9 += carry8; s8 -= carry8 << 21;
 129   carry10 = (s10 + (1<<20)) >> 21; s11 += carry10; s10 -= carry10 << 21;
 130   carry12 = (s12 + (1<<20)) >> 21; s13 += carry12; s12 -= carry12 << 21;
 131   carry14 = (s14 + (1<<20)) >> 21; s15 += carry14; s14 -= carry14 << 21;
 132   carry16 = (s16 + (1<<20)) >> 21; s17 += carry16; s16 -= carry16 << 21;
 133
 134   carry7 = (s7 + (1<<20)) >> 21; s8 += carry7; s7 -= carry7 << 21;
 135   carry9 = (s9 + (1<<20)) >> 21; s10 += carry9; s9 -= carry9 << 21;
 136   carry11 = (s11 + (1<<20)) >> 21; s12 += carry11; s11 -= carry11 << 21;
 137   carry13 = (s13 + (1<<20)) >> 21; s14 += carry13; s13 -= carry13 << 21;
 138   carry15 = (s15 + (1<<20)) >> 21; s16 += carry15; s15 -= carry15 << 21;
 139
 140   s5 += s17 * 666643;
 141   s6 += s17 * 470296;
 142   s7 += s17 * 654183;
 143   s8 -= s17 * 997805;
 144   s9 += s17 * 136657;
 145   s10 -= s17 * 683901;
 146   s17 = 0;
 147
 148   s4 += s16 * 666643;
 149   s5 += s16 * 470296;
 150   s6 += s16 * 654183;
 151   s7 -= s16 * 997805;
 152   s8 += s16 * 136657;
 153   s9 -= s16 * 683901;
 154   s16 = 0;
 155
 156   s3 += s15 * 666643;
 157   s4 += s15 * 470296;
 158   s5 += s15 * 654183;
 159   s6 -= s15 * 997805;
 160   s7 += s15 * 136657;
 161   s8 -= s15 * 683901;
 162   s15 = 0;
 163
 164   s2 += s14 * 666643;
 165   s3 += s14 * 470296;
 166   s4 += s14 * 654183;
 167   s5 -= s14 * 997805;
 168   s6 += s14 * 136657;
 169   s7 -= s14 * 683901;
 170   s14 = 0;
 171
 172   s1 += s13 * 666643;
 173   s2 += s13 * 470296;
 174   s3 += s13 * 654183;
 175   s4 -= s13 * 997805;
 176   s5 += s13 * 136657;
 177   s6 -= s13 * 683901;
 178   s13 = 0;
 179
 180   s0 += s12 * 666643;
 181   s1 += s12 * 470296;
 182   s2 += s12 * 654183;
 183   s3 -= s12 * 997805;
 184   s4 += s12 * 136657;
 185   s5 -= s12 * 683901;
 186   s12 = 0;
 187
 188   carry0 = (s0 + (1<<20)) >> 21; s1 += carry0; s0 -= carry0 << 21;
 189   carry2 = (s2 + (1<<20)) >> 21; s3 += carry2; s2 -= carry2 << 21;
 190   carry4 = (s4 + (1<<20)) >> 21; s5 += carry4; s4 -= carry4 << 21;
 191   carry6 = (s6 + (1<<20)) >> 21; s7 += carry6; s6 -= carry6 << 21;
 192   carry8 = (s8 + (1<<20)) >> 21; s9 += carry8; s8 -= carry8 << 21;
 193   carry10 = (s10 + (1<<20)) >> 21; s11 += carry10; s10 -= carry10 << 21;
 194
 195   carry1 = (s1 + (1<<20)) >> 21; s2 += carry1; s1 -= carry1 << 21;
 196   carry3 = (s3 + (1<<20)) >> 21; s4 += carry3; s3 -= carry3 << 21;
 197   carry5 = (s5 + (1<<20)) >> 21; s6 += carry5; s5 -= carry5 << 21;
 198   carry7 = (s7 + (1<<20)) >> 21; s8 += carry7; s7 -= carry7 << 21;
 199   carry9 = (s9 + (1<<20)) >> 21; s10 += carry9; s9 -= carry9 << 21;
 200   carry11 = (s11 + (1<<20)) >> 21; s12 += carry11; s11 -= carry11 << 21;
 201
 202   s0 += s12 * 666643;
 203   s1 += s12 * 470296;
 204   s2 += s12 * 654183;
 205   s3 -= s12 * 997805;
 206   s4 += s12 * 136657;
 207   s5 -= s12 * 683901;
 208   s12 = 0;
 209
 210   carry0 = s0 >> 21; s1 += carry0; s0 -= carry0 << 21;
 211   carry1 = s1 >> 21; s2 += carry1; s1 -= carry1 << 21;
 212   carry2 = s2 >> 21; s3 += carry2; s2 -= carry2 << 21;
 213   carry3 = s3 >> 21; s4 += carry3; s3 -= carry3 << 21;
 214   carry4 = s4 >> 21; s5 += carry4; s4 -= carry4 << 21;
 215   carry5 = s5 >> 21; s6 += carry5; s5 -= carry5 << 21;
 216   carry6 = s6 >> 21; s7 += carry6; s6 -= carry6 << 21;
 217   carry7 = s7 >> 21; s8 += carry7; s7 -= carry7 << 21;
 218   carry8 = s8 >> 21; s9 += carry8; s8 -= carry8 << 21;
 219   carry9 = s9 >> 21; s10 += carry9; s9 -= carry9 << 21;
 220   carry10 = s10 >> 21; s11 += carry10; s10 -= carry10 << 21;
 221   carry11 = s11 >> 21; s12 += carry11; s11 -= carry11 << 21;
 222
 223   s0 += s12 * 666643;
 224   s1 += s12 * 470296;
 225   s2 += s12 * 654183;
 226   s3 -= s12 * 997805;
 227   s4 += s12 * 136657;
 228   s5 -= s12 * 683901;
 229   s12 = 0;
 230
 231   carry0 = s0 >> 21; s1 += carry0; s0 -= carry0 << 21;
 232   carry1 = s1 >> 21; s2 += carry1; s1 -= carry1 << 21;
 233   carry2 = s2 >> 21; s3 += carry2; s2 -= carry2 << 21;
 234   carry3 = s3 >> 21; s4 += carry3; s3 -= carry3 << 21;
 235   carry4 = s4 >> 21; s5 += carry4; s4 -= carry4 << 21;
 236   carry5 = s5 >> 21; s6 += carry5; s5 -= carry5 << 21;
 237   carry6 = s6 >> 21; s7 += carry6; s6 -= carry6 << 21;
 238   carry7 = s7 >> 21; s8 += carry7; s7 -= carry7 << 21;
 239   carry8 = s8 >> 21; s9 += carry8; s8 -= carry8 << 21;
 240   carry9 = s9 >> 21; s10 += carry9; s9 -= carry9 << 21;
 241   carry10 = s10 >> 21; s11 += carry10; s10 -= carry10 << 21;
 242
 243   s[0] = s0 >> 0;
 244   s[1] = s0 >> 8;
 245   s[2] = (s0 >> 16) | (s1 << 5);
 246   s[3] = s1 >> 3;
 247   s[4] = s1 >> 11;
 248   s[5] = (s1 >> 19) | (s2 << 2);
 249   s[6] = s2 >> 6;
 250   s[7] = (s2 >> 14) | (s3 << 7);
 251   s[8] = s3 >> 1;
 252   s[9] = s3 >> 9;
 253   s[10] = (s3 >> 17) | (s4 << 4);
 254   s[11] = s4 >> 4;
 255   s[12] = s4 >> 12;
 256   s[13] = (s4 >> 20) | (s5 << 1);
 257   s[14] = s5 >> 7;
 258   s[15] = (s5 >> 15) | (s6 << 6);
 259   s[16] = s6 >> 2;
 260   s[17] = s6 >> 10;
 261   s[18] = (s6 >> 18) | (s7 << 3);
 262   s[19] = s7 >> 5;
 263   s[20] = s7 >> 13;
 264   s[21] = s8 >> 0;
 265   s[22] = s8 >> 8;
 266   s[23] = (s8 >> 16) | (s9 << 5);
 267   s[24] = s9 >> 3;
 268   s[25] = s9 >> 11;
 269   s[26] = (s9 >> 19) | (s10 << 2);
 270   s[27] = s10 >> 6;
 271   s[28] = (s10 >> 14) | (s11 << 7);
 272   s[29] = s11 >> 1;
 273   s[30] = s11 >> 9;
 274   s[31] = s11 >> 17;
 275 }