1 /*
2 * Copyright (c) 2018 Thomas Pornin <pornin@bolet.org>
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files (the
6 * "Software"), to deal in the Software without restriction, including
7 * without limitation the rights to use, copy, modify, merge, publish,
8 * distribute, sublicense, and/or sell copies of the Software, and to
9 * permit persons to whom the Software is furnished to do so, subject to
10 * the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 */
24
25 #include "inner.h"
26
27 /* see inner.h */
28 const unsigned char *
br_get_curve_OID(int curve)29 br_get_curve_OID(int curve)
30 {
31 static const unsigned char OID_secp256r1[] = {
32 0x08, 0x2a, 0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07
33 };
34 static const unsigned char OID_secp384r1[] = {
35 0x05, 0x2b, 0x81, 0x04, 0x00, 0x22
36 };
37 static const unsigned char OID_secp521r1[] = {
38 0x05, 0x2b, 0x81, 0x04, 0x00, 0x23
39 };
40
41 switch (curve) {
42 case BR_EC_secp256r1: return OID_secp256r1;
43 case BR_EC_secp384r1: return OID_secp384r1;
44 case BR_EC_secp521r1: return OID_secp521r1;
45 default:
46 return NULL;
47 }
48 }
49
50 /* see inner.h */
51 size_t
br_encode_ec_raw_der_inner(void * dest,const br_ec_private_key * sk,const br_ec_public_key * pk,int include_curve_oid)52 br_encode_ec_raw_der_inner(void *dest,
53 const br_ec_private_key *sk, const br_ec_public_key *pk,
54 int include_curve_oid)
55 {
56 /*
57 * ASN.1 format:
58 *
59 * ECPrivateKey ::= SEQUENCE {
60 * version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),
61 * privateKey OCTET STRING,
62 * parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,
63 * publicKey [1] BIT STRING OPTIONAL
64 * }
65 *
66 * The tages '[0]' and '[1]' are explicit. The 'ECParameters'
67 * is a CHOICE; in our case, it will always be an OBJECT IDENTIFIER
68 * that identifies the curve.
69 *
70 * The value of the 'privateKey' field is the raw unsigned big-endian
71 * encoding of the private key (integer modulo the curve subgroup
72 * order); there is no INTEGER tag, and the leading bit may be 1.
73 * Also, leading bytes of value 0x00 are _not_ removed.
74 *
75 * The 'publicKey' contents are the raw encoded public key point,
76 * normally uncompressed (leading byte of value 0x04, followed
77 * by the unsigned big-endian encodings of the X and Y coordinates,
78 * padded to the full field length if necessary).
79 */
80
81 size_t len_version, len_privateKey, len_parameters, len_publicKey;
82 size_t len_publicKey_bits, len_seq;
83 const unsigned char *oid;
84
85 if (include_curve_oid) {
86 oid = br_get_curve_OID(sk->curve);
87 if (oid == NULL) {
88 return 0;
89 }
90 } else {
91 oid = NULL;
92 }
93 len_version = 3;
94 len_privateKey = 1 + len_of_len(sk->xlen) + sk->xlen;
95 if (include_curve_oid) {
96 len_parameters = 4 + oid[0];
97 } else {
98 len_parameters = 0;
99 }
100 if (pk == NULL) {
101 len_publicKey = 0;
102 len_publicKey_bits = 0;
103 } else {
104 len_publicKey_bits = 2 + len_of_len(pk->qlen) + pk->qlen;
105 len_publicKey = 1 + len_of_len(len_publicKey_bits)
106 + len_publicKey_bits;
107 }
108 len_seq = len_version + len_privateKey + len_parameters + len_publicKey;
109 if (dest == NULL) {
110 return 1 + len_of_len(len_seq) + len_seq;
111 } else {
112 unsigned char *buf;
113 size_t lenlen;
114
115 buf = dest;
116 *buf ++ = 0x30; /* SEQUENCE tag */
117 lenlen = br_asn1_encode_length(buf, len_seq);
118 buf += lenlen;
119
120 /* version */
121 *buf ++ = 0x02;
122 *buf ++ = 0x01;
123 *buf ++ = 0x01;
124
125 /* privateKey */
126 *buf ++ = 0x04;
127 buf += br_asn1_encode_length(buf, sk->xlen);
128 memcpy(buf, sk->x, sk->xlen);
129 buf += sk->xlen;
130
131 /* parameters */
132 if (include_curve_oid) {
133 *buf ++ = 0xA0;
134 *buf ++ = oid[0] + 2;
135 *buf ++ = 0x06;
136 memcpy(buf, oid, oid[0] + 1);
137 buf += oid[0] + 1;
138 }
139
140 /* publicKey */
141 if (pk != NULL) {
142 *buf ++ = 0xA1;
143 buf += br_asn1_encode_length(buf, len_publicKey_bits);
144 *buf ++ = 0x03;
145 buf += br_asn1_encode_length(buf, pk->qlen + 1);
146 *buf ++ = 0x00;
147 memcpy(buf, pk->q, pk->qlen);
148 /* buf += pk->qlen; */
149 }
150
151 return 1 + lenlen + len_seq;
152 }
153 }
154
155 /* see bearssl_x509.h */
156 size_t
br_encode_ec_raw_der(void * dest,const br_ec_private_key * sk,const br_ec_public_key * pk)157 br_encode_ec_raw_der(void *dest,
158 const br_ec_private_key *sk, const br_ec_public_key *pk)
159 {
160 return br_encode_ec_raw_der_inner(dest, sk, pk, 1);
161 }
162