Bitcoin Core  22.99.0
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 https://www.opensource.org/licenses/mit-license.php.*
5  ***********************************************************************/
6 
7 #include <string.h>
8 
10 
11 int ec_privkey_import_der(const secp256k1_context* ctx, unsigned char *out32, const unsigned char *privkey, size_t privkeylen) {
12  const unsigned char *end = privkey + privkeylen;
13  int lenb = 0;
14  int len = 0;
15  memset(out32, 0, 32);
16  /* sequence header */
17  if (end < privkey+1 || *privkey != 0x30) {
18  return 0;
19  }
20  privkey++;
21  /* sequence length constructor */
22  if (end < privkey+1 || !(*privkey & 0x80)) {
23  return 0;
24  }
25  lenb = *privkey & ~0x80; privkey++;
26  if (lenb < 1 || lenb > 2) {
27  return 0;
28  }
29  if (end < privkey+lenb) {
30  return 0;
31  }
32  /* sequence length */
33  len = privkey[lenb-1] | (lenb > 1 ? privkey[lenb-2] << 8 : 0);
34  privkey += lenb;
35  if (end < privkey+len) {
36  return 0;
37  }
38  /* sequence element 0: version number (=1) */
39  if (end < privkey+3 || privkey[0] != 0x02 || privkey[1] != 0x01 || privkey[2] != 0x01) {
40  return 0;
41  }
42  privkey += 3;
43  /* sequence element 1: octet string, up to 32 bytes */
44  if (end < privkey+2 || privkey[0] != 0x04 || privkey[1] > 0x20 || end < privkey+2+privkey[1]) {
45  return 0;
46  }
47  if (privkey[1]) memcpy(out32 + 32 - privkey[1], privkey + 2, privkey[1]);
48  if (!secp256k1_ec_seckey_verify(ctx, out32)) {
49  memset(out32, 0, 32);
50  return 0;
51  }
52  return 1;
53 }
54 
55 int ec_privkey_export_der(const secp256k1_context *ctx, unsigned char *privkey, size_t *privkeylen, const unsigned char *key32, int compressed) {
56  secp256k1_pubkey pubkey;
57  size_t pubkeylen = 0;
58  if (!secp256k1_ec_pubkey_create(ctx, &pubkey, key32)) {
59  *privkeylen = 0;
60  return 0;
61  }
62  if (compressed) {
63  static const unsigned char begin[] = {
64  0x30,0x81,0xD3,0x02,0x01,0x01,0x04,0x20
65  };
66  static const unsigned char middle[] = {
67  0xA0,0x81,0x85,0x30,0x81,0x82,0x02,0x01,0x01,0x30,0x2C,0x06,0x07,0x2A,0x86,0x48,
68  0xCE,0x3D,0x01,0x01,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
69  0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
70  0xFF,0xFF,0xFE,0xFF,0xFF,0xFC,0x2F,0x30,0x06,0x04,0x01,0x00,0x04,0x01,0x07,0x04,
71  0x21,0x02,0x79,0xBE,0x66,0x7E,0xF9,0xDC,0xBB,0xAC,0x55,0xA0,0x62,0x95,0xCE,0x87,
72  0x0B,0x07,0x02,0x9B,0xFC,0xDB,0x2D,0xCE,0x28,0xD9,0x59,0xF2,0x81,0x5B,0x16,0xF8,
73  0x17,0x98,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
74  0xFF,0xFF,0xFF,0xFF,0xFE,0xBA,0xAE,0xDC,0xE6,0xAF,0x48,0xA0,0x3B,0xBF,0xD2,0x5E,
75  0x8C,0xD0,0x36,0x41,0x41,0x02,0x01,0x01,0xA1,0x24,0x03,0x22,0x00
76  };
77  unsigned char *ptr = privkey;
78  memcpy(ptr, begin, sizeof(begin)); ptr += sizeof(begin);
79  memcpy(ptr, key32, 32); ptr += 32;
80  memcpy(ptr, middle, sizeof(middle)); ptr += sizeof(middle);
81  pubkeylen = 33;
82  secp256k1_ec_pubkey_serialize(ctx, ptr, &pubkeylen, &pubkey, SECP256K1_EC_COMPRESSED);
83  ptr += pubkeylen;
84  *privkeylen = ptr - privkey;
85  } else {
86  static const unsigned char begin[] = {
87  0x30,0x82,0x01,0x13,0x02,0x01,0x01,0x04,0x20
88  };
89  static const unsigned char middle[] = {
90  0xA0,0x81,0xA5,0x30,0x81,0xA2,0x02,0x01,0x01,0x30,0x2C,0x06,0x07,0x2A,0x86,0x48,
91  0xCE,0x3D,0x01,0x01,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
92  0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
93  0xFF,0xFF,0xFE,0xFF,0xFF,0xFC,0x2F,0x30,0x06,0x04,0x01,0x00,0x04,0x01,0x07,0x04,
94  0x41,0x04,0x79,0xBE,0x66,0x7E,0xF9,0xDC,0xBB,0xAC,0x55,0xA0,0x62,0x95,0xCE,0x87,
95  0x0B,0x07,0x02,0x9B,0xFC,0xDB,0x2D,0xCE,0x28,0xD9,0x59,0xF2,0x81,0x5B,0x16,0xF8,
96  0x17,0x98,0x48,0x3A,0xDA,0x77,0x26,0xA3,0xC4,0x65,0x5D,0xA4,0xFB,0xFC,0x0E,0x11,
97  0x08,0xA8,0xFD,0x17,0xB4,0x48,0xA6,0x85,0x54,0x19,0x9C,0x47,0xD0,0x8F,0xFB,0x10,
98  0xD4,0xB8,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
99  0xFF,0xFF,0xFF,0xFF,0xFE,0xBA,0xAE,0xDC,0xE6,0xAF,0x48,0xA0,0x3B,0xBF,0xD2,0x5E,
100  0x8C,0xD0,0x36,0x41,0x41,0x02,0x01,0x01,0xA1,0x44,0x03,0x42,0x00
101  };
102  unsigned char *ptr = privkey;
103  memcpy(ptr, begin, sizeof(begin)); ptr += sizeof(begin);
104  memcpy(ptr, key32, 32); ptr += 32;
105  memcpy(ptr, middle, sizeof(middle)); ptr += sizeof(middle);
106  pubkeylen = 65;
107  secp256k1_ec_pubkey_serialize(ctx, ptr, &pubkeylen, &pubkey, SECP256K1_EC_UNCOMPRESSED);
108  ptr += pubkeylen;
109  *privkeylen = ptr - privkey;
110  }
111  return 1;
112 }
secp256k1_context_struct
Definition: secp256k1.c:75
string.h
secp256k1_ec_pubkey_serialize
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:302
ec_privkey_export_der
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.
Definition: lax_der_privatekey_parsing.c:55
SECP256K1_EC_COMPRESSED
#define SECP256K1_EC_COMPRESSED
Flag to pass to secp256k1_ec_pubkey_serialize.
Definition: secp256k1.h:190
SECP256K1_EC_UNCOMPRESSED
#define SECP256K1_EC_UNCOMPRESSED
Definition: secp256k1.h:191
lax_der_privatekey_parsing.h
secp256k1_ec_seckey_verify
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:581
ec_privkey_import_der
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.
Definition: lax_der_privatekey_parsing.c:11
secp256k1_ec_pubkey_create
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:604
secp256k1_pubkey
Opaque data structure that holds a parsed and valid public key.
Definition: secp256k1.h:70
ctx
static secp256k1_context * ctx
Definition: tests.c:42