github.com/digdeepmining/go-atheios@v1.5.13-0.20180902133602-d5687a2e6f43/crypto/secp256k1/libsecp256k1/src/eckey_impl.h (about)

     1  /**********************************************************************
     2   * Copyright (c) 2013, 2014 Pieter Wuille                             *
     3   * Distributed under the MIT software license, see the accompanying   *
     4   * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
     5   **********************************************************************/
     6  
     7  #ifndef _SECP256K1_ECKEY_IMPL_H_
     8  #define _SECP256K1_ECKEY_IMPL_H_
     9  
    10  #include "eckey.h"
    11  
    12  #include "scalar.h"
    13  #include "field.h"
    14  #include "group.h"
    15  #include "ecmult_gen.h"
    16  
    17  static int secp256k1_eckey_pubkey_parse(secp256k1_ge *elem, const unsigned char *pub, size_t size) {
    18      if (size == 33 && (pub[0] == 0x02 || pub[0] == 0x03)) {
    19          secp256k1_fe x;
    20          return secp256k1_fe_set_b32(&x, pub+1) && secp256k1_ge_set_xo_var(elem, &x, pub[0] == 0x03);
    21      } else if (size == 65 && (pub[0] == 0x04 || pub[0] == 0x06 || pub[0] == 0x07)) {
    22          secp256k1_fe x, y;
    23          if (!secp256k1_fe_set_b32(&x, pub+1) || !secp256k1_fe_set_b32(&y, pub+33)) {
    24              return 0;
    25          }
    26          secp256k1_ge_set_xy(elem, &x, &y);
    27          if ((pub[0] == 0x06 || pub[0] == 0x07) && secp256k1_fe_is_odd(&y) != (pub[0] == 0x07)) {
    28              return 0;
    29          }
    30          return secp256k1_ge_is_valid_var(elem);
    31      } else {
    32          return 0;
    33      }
    34  }
    35  
    36  static int secp256k1_eckey_pubkey_serialize(secp256k1_ge *elem, unsigned char *pub, size_t *size, int compressed) {
    37      if (secp256k1_ge_is_infinity(elem)) {
    38          return 0;
    39      }
    40      secp256k1_fe_normalize_var(&elem->x);
    41      secp256k1_fe_normalize_var(&elem->y);
    42      secp256k1_fe_get_b32(&pub[1], &elem->x);
    43      if (compressed) {
    44          *size = 33;
    45          pub[0] = 0x02 | (secp256k1_fe_is_odd(&elem->y) ? 0x01 : 0x00);
    46      } else {
    47          *size = 65;
    48          pub[0] = 0x04;
    49          secp256k1_fe_get_b32(&pub[33], &elem->y);
    50      }
    51      return 1;
    52  }
    53  
    54  static int secp256k1_eckey_privkey_tweak_add(secp256k1_scalar *key, const secp256k1_scalar *tweak) {
    55      secp256k1_scalar_add(key, key, tweak);
    56      if (secp256k1_scalar_is_zero(key)) {
    57          return 0;
    58      }
    59      return 1;
    60  }
    61  
    62  static int secp256k1_eckey_pubkey_tweak_add(const secp256k1_ecmult_context *ctx, secp256k1_ge *key, const secp256k1_scalar *tweak) {
    63      secp256k1_gej pt;
    64      secp256k1_scalar one;
    65      secp256k1_gej_set_ge(&pt, key);
    66      secp256k1_scalar_set_int(&one, 1);
    67      secp256k1_ecmult(ctx, &pt, &pt, &one, tweak);
    68  
    69      if (secp256k1_gej_is_infinity(&pt)) {
    70          return 0;
    71      }
    72      secp256k1_ge_set_gej(key, &pt);
    73      return 1;
    74  }
    75  
    76  static int secp256k1_eckey_privkey_tweak_mul(secp256k1_scalar *key, const secp256k1_scalar *tweak) {
    77      if (secp256k1_scalar_is_zero(tweak)) {
    78          return 0;
    79      }
    80  
    81      secp256k1_scalar_mul(key, key, tweak);
    82      return 1;
    83  }
    84  
    85  static int secp256k1_eckey_pubkey_tweak_mul(const secp256k1_ecmult_context *ctx, secp256k1_ge *key, const secp256k1_scalar *tweak) {
    86      secp256k1_scalar zero;
    87      secp256k1_gej pt;
    88      if (secp256k1_scalar_is_zero(tweak)) {
    89          return 0;
    90      }
    91  
    92      secp256k1_scalar_set_int(&zero, 0);
    93      secp256k1_gej_set_ge(&pt, key);
    94      secp256k1_ecmult(ctx, &pt, &pt, tweak, &zero);
    95      secp256k1_ge_set_gej(key, &pt);
    96      return 1;
    97  }
    98  
    99  #endif