ed25519/ge.h

   1 #ifndef GE_H
   2 #define GE_H
   3
   4 #include "fe.h"
   5
   6
   7 /*
   8 ge means group element.
   9
  10 Here the group is the set of pairs (x,y) of field elements (see fe.h)
  11 satisfying -x^2 + y^2 = 1 + d x^2y^2
  12 where d = -121665/121666.
  13
  14 Representations:
  15   ge_p2 (projective): (X:Y:Z) satisfying x=X/Z, y=Y/Z
  16   ge_p3 (extended): (X:Y:Z:T) satisfying x=X/Z, y=Y/Z, XY=ZT
  17   ge_p1p1 (completed): ((X:Z),(Y:T)) satisfying x=X/Z, y=Y/T
  18   ge_precomp (Duif): (y+x,y-x,2dxy)
  19 */
  20
  21 typedef struct {
  22   fe X;
  23   fe Y;
  24   fe Z;
  25 } ge_p2;
  26
  27 typedef struct {
  28   fe X;
  29   fe Y;
  30   fe Z;
  31   fe T;
  32 } ge_p3;
  33
  34 typedef struct {
  35   fe X;
  36   fe Y;
  37   fe Z;
  38   fe T;
  39 } ge_p1p1;
  40
  41 typedef struct {
  42   fe yplusx;
  43   fe yminusx;
  44   fe xy2d;
  45 } ge_precomp;
  46
  47 typedef struct {
  48   fe YplusX;
  49   fe YminusX;
  50   fe Z;
  51   fe T2d;
  52 } ge_cached;
  53
  54 void ge_p3_tobytes(unsigned char *s, const ge_p3 *h);
  55 void ge_tobytes(unsigned char *s, const ge_p2 *h);
  56 int ge_frombytes_negate_vartime(ge_p3 *h, const unsigned char *s);
  57
  58 void ge_add(ge_p1p1 *r, const ge_p3 *p, const ge_cached *q);
  59 void ge_sub(ge_p1p1 *r, const ge_p3 *p, const ge_cached *q);
  60 void ge_double_scalarmult_vartime(ge_p2 *r, const unsigned char *a, const ge_p3 *A, const unsigned char *b);
  61 void ge_madd(ge_p1p1 *r, const ge_p3 *p, const ge_precomp *q);
  62 void ge_msub(ge_p1p1 *r, const ge_p3 *p, const ge_precomp *q);
  63 void ge_scalarmult_base(ge_p3 *h, const unsigned char *a);
  64
  65 void ge_p1p1_to_p2(ge_p2 *r, const ge_p1p1 *p);
  66 void ge_p1p1_to_p3(ge_p3 *r, const ge_p1p1 *p);
  67 void ge_p2_0(ge_p2 *h);
  68 void ge_p2_dbl(ge_p1p1 *r, const ge_p2 *p);
  69 void ge_p3_0(ge_p3 *h);
  70 void ge_p3_dbl(ge_p1p1 *r, const ge_p3 *p);
  71 void ge_p3_to_cached(ge_cached *r, const ge_p3 *p);
  72 void ge_p3_to_p2(ge_p2 *r, const ge_p3 *p);
  73
  74 #endif