1*0957b409SSimon J. Gerraty /*
2*0957b409SSimon J. Gerraty * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
3*0957b409SSimon J. Gerraty *
4*0957b409SSimon J. Gerraty * Permission is hereby granted, free of charge, to any person obtaining
5*0957b409SSimon J. Gerraty * a copy of this software and associated documentation files (the
6*0957b409SSimon J. Gerraty * "Software"), to deal in the Software without restriction, including
7*0957b409SSimon J. Gerraty * without limitation the rights to use, copy, modify, merge, publish,
8*0957b409SSimon J. Gerraty * distribute, sublicense, and/or sell copies of the Software, and to
9*0957b409SSimon J. Gerraty * permit persons to whom the Software is furnished to do so, subject to
10*0957b409SSimon J. Gerraty * the following conditions:
11*0957b409SSimon J. Gerraty *
12*0957b409SSimon J. Gerraty * The above copyright notice and this permission notice shall be
13*0957b409SSimon J. Gerraty * included in all copies or substantial portions of the Software.
14*0957b409SSimon J. Gerraty *
15*0957b409SSimon J. Gerraty * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16*0957b409SSimon J. Gerraty * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17*0957b409SSimon J. Gerraty * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18*0957b409SSimon J. Gerraty * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19*0957b409SSimon J. Gerraty * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20*0957b409SSimon J. Gerraty * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21*0957b409SSimon J. Gerraty * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22*0957b409SSimon J. Gerraty * SOFTWARE.
23*0957b409SSimon J. Gerraty */
24*0957b409SSimon J. Gerraty
25*0957b409SSimon J. Gerraty #include "inner.h"
26*0957b409SSimon J. Gerraty
27*0957b409SSimon J. Gerraty /* see bearssl_ec.h */
28*0957b409SSimon J. Gerraty size_t
br_ecdsa_asn1_to_raw(void * sig,size_t sig_len)29*0957b409SSimon J. Gerraty br_ecdsa_asn1_to_raw(void *sig, size_t sig_len)
30*0957b409SSimon J. Gerraty {
31*0957b409SSimon J. Gerraty /*
32*0957b409SSimon J. Gerraty * Note: this code is a bit lenient in that it accepts a few
33*0957b409SSimon J. Gerraty * deviations to DER with regards to minimality of encoding of
34*0957b409SSimon J. Gerraty * lengths and integer values. These deviations are still
35*0957b409SSimon J. Gerraty * unambiguous.
36*0957b409SSimon J. Gerraty *
37*0957b409SSimon J. Gerraty * Signature format is a SEQUENCE of two INTEGER values. We
38*0957b409SSimon J. Gerraty * support only integers of less than 127 bytes each (signed
39*0957b409SSimon J. Gerraty * encoding) so the resulting raw signature will have length
40*0957b409SSimon J. Gerraty * at most 254 bytes.
41*0957b409SSimon J. Gerraty */
42*0957b409SSimon J. Gerraty
43*0957b409SSimon J. Gerraty unsigned char *buf, *r, *s;
44*0957b409SSimon J. Gerraty size_t zlen, rlen, slen, off;
45*0957b409SSimon J. Gerraty unsigned char tmp[254];
46*0957b409SSimon J. Gerraty
47*0957b409SSimon J. Gerraty buf = sig;
48*0957b409SSimon J. Gerraty if (sig_len < 8) {
49*0957b409SSimon J. Gerraty return 0;
50*0957b409SSimon J. Gerraty }
51*0957b409SSimon J. Gerraty
52*0957b409SSimon J. Gerraty /*
53*0957b409SSimon J. Gerraty * First byte is SEQUENCE tag.
54*0957b409SSimon J. Gerraty */
55*0957b409SSimon J. Gerraty if (buf[0] != 0x30) {
56*0957b409SSimon J. Gerraty return 0;
57*0957b409SSimon J. Gerraty }
58*0957b409SSimon J. Gerraty
59*0957b409SSimon J. Gerraty /*
60*0957b409SSimon J. Gerraty * The SEQUENCE length will be encoded over one or two bytes. We
61*0957b409SSimon J. Gerraty * limit the total SEQUENCE contents to 255 bytes, because it
62*0957b409SSimon J. Gerraty * makes things simpler; this is enough for subgroup orders up
63*0957b409SSimon J. Gerraty * to 999 bits.
64*0957b409SSimon J. Gerraty */
65*0957b409SSimon J. Gerraty zlen = buf[1];
66*0957b409SSimon J. Gerraty if (zlen > 0x80) {
67*0957b409SSimon J. Gerraty if (zlen != 0x81) {
68*0957b409SSimon J. Gerraty return 0;
69*0957b409SSimon J. Gerraty }
70*0957b409SSimon J. Gerraty zlen = buf[2];
71*0957b409SSimon J. Gerraty if (zlen != sig_len - 3) {
72*0957b409SSimon J. Gerraty return 0;
73*0957b409SSimon J. Gerraty }
74*0957b409SSimon J. Gerraty off = 3;
75*0957b409SSimon J. Gerraty } else {
76*0957b409SSimon J. Gerraty if (zlen != sig_len - 2) {
77*0957b409SSimon J. Gerraty return 0;
78*0957b409SSimon J. Gerraty }
79*0957b409SSimon J. Gerraty off = 2;
80*0957b409SSimon J. Gerraty }
81*0957b409SSimon J. Gerraty
82*0957b409SSimon J. Gerraty /*
83*0957b409SSimon J. Gerraty * First INTEGER (r).
84*0957b409SSimon J. Gerraty */
85*0957b409SSimon J. Gerraty if (buf[off ++] != 0x02) {
86*0957b409SSimon J. Gerraty return 0;
87*0957b409SSimon J. Gerraty }
88*0957b409SSimon J. Gerraty rlen = buf[off ++];
89*0957b409SSimon J. Gerraty if (rlen >= 0x80) {
90*0957b409SSimon J. Gerraty return 0;
91*0957b409SSimon J. Gerraty }
92*0957b409SSimon J. Gerraty r = buf + off;
93*0957b409SSimon J. Gerraty off += rlen;
94*0957b409SSimon J. Gerraty
95*0957b409SSimon J. Gerraty /*
96*0957b409SSimon J. Gerraty * Second INTEGER (s).
97*0957b409SSimon J. Gerraty */
98*0957b409SSimon J. Gerraty if (off + 2 > sig_len) {
99*0957b409SSimon J. Gerraty return 0;
100*0957b409SSimon J. Gerraty }
101*0957b409SSimon J. Gerraty if (buf[off ++] != 0x02) {
102*0957b409SSimon J. Gerraty return 0;
103*0957b409SSimon J. Gerraty }
104*0957b409SSimon J. Gerraty slen = buf[off ++];
105*0957b409SSimon J. Gerraty if (slen >= 0x80 || slen != sig_len - off) {
106*0957b409SSimon J. Gerraty return 0;
107*0957b409SSimon J. Gerraty }
108*0957b409SSimon J. Gerraty s = buf + off;
109*0957b409SSimon J. Gerraty
110*0957b409SSimon J. Gerraty /*
111*0957b409SSimon J. Gerraty * Removing leading zeros from r and s.
112*0957b409SSimon J. Gerraty */
113*0957b409SSimon J. Gerraty while (rlen > 0 && *r == 0) {
114*0957b409SSimon J. Gerraty rlen --;
115*0957b409SSimon J. Gerraty r ++;
116*0957b409SSimon J. Gerraty }
117*0957b409SSimon J. Gerraty while (slen > 0 && *s == 0) {
118*0957b409SSimon J. Gerraty slen --;
119*0957b409SSimon J. Gerraty s ++;
120*0957b409SSimon J. Gerraty }
121*0957b409SSimon J. Gerraty
122*0957b409SSimon J. Gerraty /*
123*0957b409SSimon J. Gerraty * Compute common length for the two integers, then copy integers
124*0957b409SSimon J. Gerraty * into the temporary buffer, and finally copy it back over the
125*0957b409SSimon J. Gerraty * signature buffer.
126*0957b409SSimon J. Gerraty */
127*0957b409SSimon J. Gerraty zlen = rlen > slen ? rlen : slen;
128*0957b409SSimon J. Gerraty sig_len = zlen << 1;
129*0957b409SSimon J. Gerraty memset(tmp, 0, sig_len);
130*0957b409SSimon J. Gerraty memcpy(tmp + zlen - rlen, r, rlen);
131*0957b409SSimon J. Gerraty memcpy(tmp + sig_len - slen, s, slen);
132*0957b409SSimon J. Gerraty memcpy(sig, tmp, sig_len);
133*0957b409SSimon J. Gerraty return sig_len;
134*0957b409SSimon J. Gerraty }
135