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 "util.h"
13  #include "scalar.h"
14  #include "field.h"
15  #include "group.h"
16  #include "ecmult_gen.h"
17  
18  static int secp256k1_eckey_pubkey_parse(secp256k1_ge *elem, const unsigned char *pub, size_t size) {
19      if (size == 33 && (pub[0] == SECP256K1_TAG_PUBKEY_EVEN || pub[0] == SECP256K1_TAG_PUBKEY_ODD)) {
20          secp256k1_fe x;
21          return secp256k1_fe_set_b32_limit(&x, pub+1) && secp256k1_ge_set_xo_var(elem, &x, pub[0] == SECP256K1_TAG_PUBKEY_ODD);
22      } else if (size == 65 && (pub[0] == SECP256K1_TAG_PUBKEY_UNCOMPRESSED || pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_EVEN || pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_ODD)) {
23          secp256k1_fe x, y;
24          if (!secp256k1_fe_set_b32_limit(&x, pub+1) || !secp256k1_fe_set_b32_limit(&y, pub+33)) {
25              return 0;
26          }
27          secp256k1_ge_set_xy(elem, &x, &y);
28          if ((pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_EVEN || pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_ODD) &&
29              secp256k1_fe_is_odd(&y) != (pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_ODD)) {
30              return 0;
31          }
32          return secp256k1_ge_is_valid_var(elem);
33      } else {
34          return 0;
35      }
36  }
37  
38  static void secp256k1_eckey_pubkey_serialize33(secp256k1_ge *elem, unsigned char *pub33) {
39      VERIFY_CHECK(!secp256k1_ge_is_infinity(elem));
40  
41      secp256k1_fe_normalize_var(&elem->x);
42      secp256k1_fe_normalize_var(&elem->y);
43      pub33[0] = secp256k1_fe_is_odd(&elem->y) ? SECP256K1_TAG_PUBKEY_ODD : SECP256K1_TAG_PUBKEY_EVEN;
44      secp256k1_fe_get_b32(&pub33[1], &elem->x);
45  }
46  
47  static void secp256k1_eckey_pubkey_serialize65(secp256k1_ge *elem, unsigned char *pub65) {
48      VERIFY_CHECK(!secp256k1_ge_is_infinity(elem));
49  
50      secp256k1_fe_normalize_var(&elem->x);
51      secp256k1_fe_normalize_var(&elem->y);
52      pub65[0] = SECP256K1_TAG_PUBKEY_UNCOMPRESSED;
53      secp256k1_fe_get_b32(&pub65[1], &elem->x);
54      secp256k1_fe_get_b32(&pub65[33], &elem->y);
55  }
56  
57  static int secp256k1_eckey_privkey_tweak_add(secp256k1_scalar *key, const secp256k1_scalar *tweak) {
58      secp256k1_scalar_add(key, key, tweak);
59      return !secp256k1_scalar_is_zero(key);
60  }
61  
62  static int secp256k1_eckey_pubkey_tweak_add(secp256k1_ge *key, const secp256k1_scalar *tweak) {
63      secp256k1_gej pt;
64      secp256k1_gej_set_ge(&pt, key);
65      secp256k1_ecmult(&pt, &pt, &secp256k1_scalar_one, tweak);
66  
67      if (secp256k1_gej_is_infinity(&pt)) {
68          return 0;
69      }
70      secp256k1_ge_set_gej(key, &pt);
71      return 1;
72  }
73  
74  static int secp256k1_eckey_privkey_tweak_mul(secp256k1_scalar *key, const secp256k1_scalar *tweak) {
75      int ret;
76      ret = !secp256k1_scalar_is_zero(tweak);
77  
78      secp256k1_scalar_mul(key, key, tweak);
79      return ret;
80  }
81  
82  static int secp256k1_eckey_pubkey_tweak_mul(secp256k1_ge *key, const secp256k1_scalar *tweak) {
83      secp256k1_gej pt;
84      if (secp256k1_scalar_is_zero(tweak)) {
85          return 0;
86      }
87  
88      secp256k1_gej_set_ge(&pt, key);
89      secp256k1_ecmult(&pt, &pt, tweak, NULL);
90      secp256k1_ge_set_gej(key, &pt);
91      return 1;
92  }
93  
94  #endif /* SECP256K1_ECKEY_IMPL_H */