lax_der_privatekey_parsing.c raw
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
9 #include "lax_der_privatekey_parsing.h"
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 }
113