1 /* $OpenBSD: curve25519_internal.h,v 1.3 2019/05/11 15:55:52 tb Exp $ */ 2 /* 3 * Copyright (c) 2015, Google Inc. 4 * 5 * Permission to use, copy, modify, and/or distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 12 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 14 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 15 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #ifndef HEADER_CURVE25519_INTERNAL_H 19 #define HEADER_CURVE25519_INTERNAL_H 20 21 #include <stdint.h> 22 23 __BEGIN_HIDDEN_DECLS 24 25 /* fe means field element. Here the field is \Z/(2^255-19). An element t, 26 * entries t[0]...t[9], represents the integer t[0]+2^26 t[1]+2^51 t[2]+2^77 27 * t[3]+2^102 t[4]+...+2^230 t[9]. Bounds on each t[i] vary depending on 28 * context. */ 29 typedef int32_t fe[10]; 30 31 /* ge means group element. 32 33 * Here the group is the set of pairs (x,y) of field elements (see fe.h) 34 * satisfying -x^2 + y^2 = 1 + d x^2y^2 35 * where d = -121665/121666. 36 * 37 * Representations: 38 * ge_p2 (projective): (X:Y:Z) satisfying x=X/Z, y=Y/Z 39 * ge_p3 (extended): (X:Y:Z:T) satisfying x=X/Z, y=Y/Z, XY=ZT 40 * ge_p1p1 (completed): ((X:Z),(Y:T)) satisfying x=X/Z, y=Y/T 41 * ge_precomp (Duif): (y+x,y-x,2dxy) */ 42 43 typedef struct { 44 fe X; 45 fe Y; 46 fe Z; 47 } ge_p2; 48 49 typedef struct { 50 fe X; 51 fe Y; 52 fe Z; 53 fe T; 54 } ge_p3; 55 56 typedef struct { 57 fe X; 58 fe Y; 59 fe Z; 60 fe T; 61 } ge_p1p1; 62 63 typedef struct { 64 fe yplusx; 65 fe yminusx; 66 fe xy2d; 67 } ge_precomp; 68 69 typedef struct { 70 fe YplusX; 71 fe YminusX; 72 fe Z; 73 fe T2d; 74 } ge_cached; 75 76 void x25519_ge_tobytes(uint8_t *s, const ge_p2 *h); 77 int x25519_ge_frombytes_vartime(ge_p3 *h, const uint8_t *s); 78 void x25519_ge_p3_to_cached(ge_cached *r, const ge_p3 *p); 79 void x25519_ge_p1p1_to_p2(ge_p2 *r, const ge_p1p1 *p); 80 void x25519_ge_p1p1_to_p3(ge_p3 *r, const ge_p1p1 *p); 81 void x25519_ge_add(ge_p1p1 *r, const ge_p3 *p, const ge_cached *q); 82 void x25519_ge_sub(ge_p1p1 *r, const ge_p3 *p, const ge_cached *q); 83 void x25519_ge_scalarmult_small_precomp(ge_p3 *h, const uint8_t a[32], 84 const uint8_t precomp_table[15 * 2 * 32]); 85 void x25519_ge_scalarmult_base(ge_p3 *h, const uint8_t a[32]); 86 void x25519_ge_scalarmult(ge_p2 *r, const uint8_t *scalar, const ge_p3 *A); 87 void x25519_sc_reduce(uint8_t *s); 88 89 void x25519_public_from_private(uint8_t out_public_value[32], 90 const uint8_t private_key[32]); 91 92 void x25519_scalar_mult(uint8_t out[32], const uint8_t scalar[32], 93 const uint8_t point[32]); 94 void x25519_scalar_mult_generic(uint8_t out[32], const uint8_t scalar[32], 95 const uint8_t point[32]); 96 97 __END_HIDDEN_DECLS 98 99 #endif /* HEADER_CURVE25519_INTERNAL_H */ 100