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 */
28const unsigned char *
29br_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 */
51size_t
52br_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 */
156size_t
157br_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