release/src/router/libsodium/src/libsodium/crypto_sign/edwards25519sha512batch/ref/sc25519_edwards25519sha512batch.c

   1 #include "sc25519.h"
   2
   3 /*Arithmetic modulo the group order n = 2^252 +  27742317777372353535851937790883648493 = 7237005577332262213973186563042994240857116359379907606001950938285454250989 */
   4
   5 static const crypto_uint32 m[32] = {0xED, 0xD3, 0xF5, 0x5C, 0x1A, 0x63, 0x12, 0x58, 0xD6, 0x9C, 0xF7, 0xA2, 0xDE, 0xF9, 0xDE, 0x14,
   6                                     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10};
   7
   8 static const crypto_uint32 mu[33] = {0x1B, 0x13, 0x2C, 0x0A, 0xA3, 0xE5, 0x9C, 0xED, 0xA7, 0x29, 0x63, 0x08, 0x5D, 0x21, 0x06, 0x21,
   9                                      0xEB, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x0F};
  10
  11 /* Reduce coefficients of r before calling reduce_add_sub */
  12 static void reduce_add_sub(sc25519 *r)
  13 {
  14   int i, b, pb=0, nb;
  15   unsigned char t[32];
  16
  17   for(i=0;i<32;i++)
  18   {
  19     b = (r->v[i]<pb+m[i]);
  20     t[i] = r->v[i]-pb-m[i]+b*256;
  21     pb = b;
  22   }
  23   nb = 1-b;
  24   for(i=0;i<32;i++)
  25     r->v[i] = r->v[i]*b + t[i]*nb;
  26 }
  27
  28 /* Reduce coefficients of x before calling barrett_reduce */
  29 static void barrett_reduce(sc25519 *r, const crypto_uint32 x[64])
  30 {
  31   /* See HAC, Alg. 14.42 */
  32   int i,j;
  33   crypto_uint32 q2[66] = {0};
  34   crypto_uint32 *q3 = q2 + 33;
  35   crypto_uint32 r1[33];
  36   crypto_uint32 r2[33] = {0};
  37   crypto_uint32 carry;
  38   int b, pb=0;
  39
  40   for(i=0;i<33;i++)
  41     for(j=0;j<33;j++)
  42       if(i+j >= 31) q2[i+j] += mu[i]*x[j+31];
  43   carry = q2[31] >> 8;
  44   q2[32] += carry;
  45   carry = q2[32] >> 8;
  46   q2[33] += carry;
  47
  48   for(i=0;i<33;i++)r1[i] = x[i];
  49   for(i=0;i<32;i++)
  50     for(j=0;j<33;j++)
  51       if(i+j < 33) r2[i+j] += m[i]*q3[j];
  52
  53   for(i=0;i<32;i++)
  54   {
  55     carry = r2[i] >> 8;
  56     r2[i+1] += carry;
  57     r2[i] &= 0xff;
  58   }
  59
  60   for(i=0;i<32;i++)
  61   {
  62     b = (r1[i]<pb+r2[i]);
  63     r->v[i] = r1[i]-pb-r2[i]+b*256;
  64     pb = b;
  65   }
  66
  67   /* XXX: Can it really happen that r<0?, See HAC, Alg 14.42, Step 3
  68    * If so: Handle  it here!
  69    */
  70
  71   reduce_add_sub(r);
  72   reduce_add_sub(r);
  73 }
  74
  75 /*
  76 static int iszero(const sc25519 *x)
  77 {
  78   // Implement
  79   return 0;
  80 }
  81 */
  82
  83 void sc25519_from32bytes(sc25519 *r, const unsigned char x[32])
  84 {
  85   int i;
  86   crypto_uint32 t[64] = {0};
  87   for(i=0;i<32;i++) t[i] = x[i];
  88   barrett_reduce(r, t);
  89 }
  90
  91 void sc25519_from64bytes(sc25519 *r, const unsigned char x[64])
  92 {
  93   int i;
  94   crypto_uint32 t[64] = {0};
  95   for(i=0;i<64;i++) t[i] = x[i];
  96   barrett_reduce(r, t);
  97 }
  98
  99 /* XXX: What we actually want for crypto_group is probably just something like
 100  * void sc25519_frombytes(sc25519 *r, const unsigned char *x, size_t xlen)
 101  */
 102
 103 void sc25519_to32bytes(unsigned char r[32], const sc25519 *x)
 104 {
 105   int i;
 106   for(i=0;i<32;i++) r[i] = x->v[i];
 107 }
 108
 109 void sc25519_add(sc25519 *r, const sc25519 *x, const sc25519 *y)
 110 {
 111   int i, carry;
 112   for(i=0;i<32;i++) r->v[i] = x->v[i] + y->v[i];
 113   for(i=0;i<31;i++)
 114   {
 115     carry = r->v[i] >> 8;
 116     r->v[i+1] += carry;
 117     r->v[i] &= 0xff;
 118   }
 119   reduce_add_sub(r);
 120 }
 121
 122 void sc25519_mul(sc25519 *r, const sc25519 *x, const sc25519 *y)
 123 {
 124   int i,j,carry;
 125   crypto_uint32 t[64];
 126   for(i=0;i<64;i++)t[i] = 0;
 127
 128   for(i=0;i<32;i++)
 129     for(j=0;j<32;j++)
 130       t[i+j] += x->v[i] * y->v[j];
 131
 132   /* Reduce coefficients */
 133   for(i=0;i<63;i++)
 134   {
 135     carry = t[i] >> 8;
 136     t[i+1] += carry;
 137     t[i] &= 0xff;
 138   }
 139
 140   barrett_reduce(r, t);
 141 }
 142
 143 void sc25519_square(sc25519 *r, const sc25519 *x)
 144 {
 145   sc25519_mul(r, x, x);
 146 }