github.com/ethereum/go-ethereum@v1.16.1/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 https://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] == SECP256K1_TAG_PUBKEY_EVEN || pub[0] == SECP256K1_TAG_PUBKEY_ODD)) {
    19          secp256k1_fe x;
    20          return secp256k1_fe_set_b32_limit(&x, pub+1) && secp256k1_ge_set_xo_var(elem, &x, pub[0] == SECP256K1_TAG_PUBKEY_ODD);
    21      } else if (size == 65 && (pub[0] == SECP256K1_TAG_PUBKEY_UNCOMPRESSED || pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_EVEN || pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_ODD)) {
    22          secp256k1_fe x, y;
    23          if (!secp256k1_fe_set_b32_limit(&x, pub+1) || !secp256k1_fe_set_b32_limit(&y, pub+33)) {
    24              return 0;
    25          }
    26          secp256k1_ge_set_xy(elem, &x, &y);
    27          if ((pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_EVEN || pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_ODD) &&
    28              secp256k1_fe_is_odd(&y) != (pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_ODD)) {
    29              return 0;
    30          }
    31          return secp256k1_ge_is_valid_var(elem);
    32      } else {
    33          return 0;
    34      }
    35  }
    36  
    37  static int secp256k1_eckey_pubkey_serialize(secp256k1_ge *elem, unsigned char *pub, size_t *size, int compressed) {
    38      if (secp256k1_ge_is_infinity(elem)) {
    39          return 0;
    40      }
    41      secp256k1_fe_normalize_var(&elem->x);
    42      secp256k1_fe_normalize_var(&elem->y);
    43      secp256k1_fe_get_b32(&pub[1], &elem->x);
    44      if (compressed) {
    45          *size = 33;
    46          pub[0] = secp256k1_fe_is_odd(&elem->y) ? SECP256K1_TAG_PUBKEY_ODD : SECP256K1_TAG_PUBKEY_EVEN;
    47      } else {
    48          *size = 65;
    49          pub[0] = SECP256K1_TAG_PUBKEY_UNCOMPRESSED;
    50          secp256k1_fe_get_b32(&pub[33], &elem->y);
    51      }
    52      return 1;
    53  }
    54  
    55  static int secp256k1_eckey_privkey_tweak_add(secp256k1_scalar *key, const secp256k1_scalar *tweak) {
    56      secp256k1_scalar_add(key, key, tweak);
    57      return !secp256k1_scalar_is_zero(key);
    58  }
    59  
    60  static int secp256k1_eckey_pubkey_tweak_add(secp256k1_ge *key, const secp256k1_scalar *tweak) {
    61      secp256k1_gej pt;
    62      secp256k1_gej_set_ge(&pt, key);
    63      secp256k1_ecmult(&pt, &pt, &secp256k1_scalar_one, tweak);
    64  
    65      if (secp256k1_gej_is_infinity(&pt)) {
    66          return 0;
    67      }
    68      secp256k1_ge_set_gej(key, &pt);
    69      return 1;
    70  }
    71  
    72  static int secp256k1_eckey_privkey_tweak_mul(secp256k1_scalar *key, const secp256k1_scalar *tweak) {
    73      int ret;
    74      ret = !secp256k1_scalar_is_zero(tweak);
    75  
    76      secp256k1_scalar_mul(key, key, tweak);
    77      return ret;
    78  }
    79  
    80  static int secp256k1_eckey_pubkey_tweak_mul(secp256k1_ge *key, const secp256k1_scalar *tweak) {
    81      secp256k1_gej pt;
    82      if (secp256k1_scalar_is_zero(tweak)) {
    83          return 0;
    84      }
    85  
    86      secp256k1_gej_set_ge(&pt, key);
    87      secp256k1_ecmult(&pt, &pt, tweak, &secp256k1_scalar_zero);
    88      secp256k1_ge_set_gej(key, &pt);
    89      return 1;
    90  }
    91  
    92  #endif /* SECP256K1_ECKEY_IMPL_H */