Bitcoin Core  0.20.99
P2P Digital Currency
lax_der_privatekey_parsing.c
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1 /**********************************************************************
2  * Copyright (c) 2014, 2015 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 #include <string.h>
8 #include <secp256k1.h>
9 
11 
12 int ec_privkey_import_der(const secp256k1_context* ctx, unsigned char *out32, const unsigned char *privkey, size_t privkeylen) {
13  const unsigned char *end = privkey + privkeylen;
14  int lenb = 0;
15  int len = 0;
16  memset(out32, 0, 32);
17  /* sequence header */
18  if (end < privkey+1 || *privkey != 0x30) {
19  return 0;
20  }
21  privkey++;
22  /* sequence length constructor */
23  if (end < privkey+1 || !(*privkey & 0x80)) {
24  return 0;
25  }
26  lenb = *privkey & ~0x80; privkey++;
27  if (lenb < 1 || lenb > 2) {
28  return 0;
29  }
30  if (end < privkey+lenb) {
31  return 0;
32  }
33  /* sequence length */
34  len = privkey[lenb-1] | (lenb > 1 ? privkey[lenb-2] << 8 : 0);
35  privkey += lenb;
36  if (end < privkey+len) {
37  return 0;
38  }
39  /* sequence element 0: version number (=1) */
40  if (end < privkey+3 || privkey[0] != 0x02 || privkey[1] != 0x01 || privkey[2] != 0x01) {
41  return 0;
42  }
43  privkey += 3;
44  /* sequence element 1: octet string, up to 32 bytes */
45  if (end < privkey+2 || privkey[0] != 0x04 || privkey[1] > 0x20 || end < privkey+2+privkey[1]) {
46  return 0;
47  }
48  memcpy(out32 + 32 - privkey[1], privkey + 2, privkey[1]);
49  if (!secp256k1_ec_seckey_verify(ctx, out32)) {
50  memset(out32, 0, 32);
51  return 0;
52  }
53  return 1;
54 }
55 
56 int ec_privkey_export_der(const secp256k1_context *ctx, unsigned char *privkey, size_t *privkeylen, const unsigned char *key32, int compressed) {
57  secp256k1_pubkey pubkey;
58  size_t pubkeylen = 0;
59  if (!secp256k1_ec_pubkey_create(ctx, &pubkey, key32)) {
60  *privkeylen = 0;
61  return 0;
62  }
63  if (compressed) {
64  static const unsigned char begin[] = {
65  0x30,0x81,0xD3,0x02,0x01,0x01,0x04,0x20
66  };
67  static const unsigned char middle[] = {
68  0xA0,0x81,0x85,0x30,0x81,0x82,0x02,0x01,0x01,0x30,0x2C,0x06,0x07,0x2A,0x86,0x48,
69  0xCE,0x3D,0x01,0x01,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
70  0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
71  0xFF,0xFF,0xFE,0xFF,0xFF,0xFC,0x2F,0x30,0x06,0x04,0x01,0x00,0x04,0x01,0x07,0x04,
72  0x21,0x02,0x79,0xBE,0x66,0x7E,0xF9,0xDC,0xBB,0xAC,0x55,0xA0,0x62,0x95,0xCE,0x87,
73  0x0B,0x07,0x02,0x9B,0xFC,0xDB,0x2D,0xCE,0x28,0xD9,0x59,0xF2,0x81,0x5B,0x16,0xF8,
74  0x17,0x98,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
75  0xFF,0xFF,0xFF,0xFF,0xFE,0xBA,0xAE,0xDC,0xE6,0xAF,0x48,0xA0,0x3B,0xBF,0xD2,0x5E,
76  0x8C,0xD0,0x36,0x41,0x41,0x02,0x01,0x01,0xA1,0x24,0x03,0x22,0x00
77  };
78  unsigned char *ptr = privkey;
79  memcpy(ptr, begin, sizeof(begin)); ptr += sizeof(begin);
80  memcpy(ptr, key32, 32); ptr += 32;
81  memcpy(ptr, middle, sizeof(middle)); ptr += sizeof(middle);
82  pubkeylen = 33;
83  secp256k1_ec_pubkey_serialize(ctx, ptr, &pubkeylen, &pubkey, SECP256K1_EC_COMPRESSED);
84  ptr += pubkeylen;
85  *privkeylen = ptr - privkey;
86  } else {
87  static const unsigned char begin[] = {
88  0x30,0x82,0x01,0x13,0x02,0x01,0x01,0x04,0x20
89  };
90  static const unsigned char middle[] = {
91  0xA0,0x81,0xA5,0x30,0x81,0xA2,0x02,0x01,0x01,0x30,0x2C,0x06,0x07,0x2A,0x86,0x48,
92  0xCE,0x3D,0x01,0x01,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
93  0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
94  0xFF,0xFF,0xFE,0xFF,0xFF,0xFC,0x2F,0x30,0x06,0x04,0x01,0x00,0x04,0x01,0x07,0x04,
95  0x41,0x04,0x79,0xBE,0x66,0x7E,0xF9,0xDC,0xBB,0xAC,0x55,0xA0,0x62,0x95,0xCE,0x87,
96  0x0B,0x07,0x02,0x9B,0xFC,0xDB,0x2D,0xCE,0x28,0xD9,0x59,0xF2,0x81,0x5B,0x16,0xF8,
97  0x17,0x98,0x48,0x3A,0xDA,0x77,0x26,0xA3,0xC4,0x65,0x5D,0xA4,0xFB,0xFC,0x0E,0x11,
98  0x08,0xA8,0xFD,0x17,0xB4,0x48,0xA6,0x85,0x54,0x19,0x9C,0x47,0xD0,0x8F,0xFB,0x10,
99  0xD4,0xB8,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
100  0xFF,0xFF,0xFF,0xFF,0xFE,0xBA,0xAE,0xDC,0xE6,0xAF,0x48,0xA0,0x3B,0xBF,0xD2,0x5E,
101  0x8C,0xD0,0x36,0x41,0x41,0x02,0x01,0x01,0xA1,0x44,0x03,0x42,0x00
102  };
103  unsigned char *ptr = privkey;
104  memcpy(ptr, begin, sizeof(begin)); ptr += sizeof(begin);
105  memcpy(ptr, key32, 32); ptr += 32;
106  memcpy(ptr, middle, sizeof(middle)); ptr += sizeof(middle);
107  pubkeylen = 65;
108  secp256k1_ec_pubkey_serialize(ctx, ptr, &pubkeylen, &pubkey, SECP256K1_EC_UNCOMPRESSED);
109  ptr += pubkeylen;
110  *privkeylen = ptr - privkey;
111  }
112  return 1;
113 }
int ec_privkey_export_der(const secp256k1_context *ctx, unsigned char *privkey, size_t *privkeylen, const unsigned char *key32, int compressed)
Export a private key in DER format.
SECP256K1_API int secp256k1_ec_pubkey_serialize(const secp256k1_context *ctx, unsigned char *output, size_t *outputlen, const secp256k1_pubkey *pubkey, unsigned int flags) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4)
Serialize a pubkey object into a serialized byte sequence.
Definition: secp256k1.c:287
int ec_privkey_import_der(const secp256k1_context *ctx, unsigned char *out32, const unsigned char *privkey, size_t privkeylen)
Import a private key in DER format.
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_create(const secp256k1_context *ctx, secp256k1_pubkey *pubkey, const unsigned char *seckey) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3)
Compute the public key for a secret key.
Definition: secp256k1.c:551
#define SECP256K1_EC_UNCOMPRESSED
Definition: secp256k1.h:177
#define SECP256K1_EC_COMPRESSED
Flag to pass to secp256k1_ec_pubkey_serialize.
Definition: secp256k1.h:176
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_verify(const secp256k1_context *ctx, const unsigned char *seckey) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2)
Verify an ECDSA secret key.
Definition: secp256k1.c:540
static secp256k1_context * ctx
Definition: tests.c:36
void * memcpy(void *a, const void *b, size_t c)
Opaque data structure that holds a parsed and valid public key.
Definition: secp256k1.h:67