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 /*
28*0957b409SSimon J. Gerraty * Compute ASN.1 encoded length for the provided integer. The ASN.1
29*0957b409SSimon J. Gerraty * encoding is signed, so its leading bit must have value 0; it must
30*0957b409SSimon J. Gerraty * also be of minimal length (so leading bytes of value 0 must be
31*0957b409SSimon J. Gerraty * removed, except if that would contradict the rule about the sign
32*0957b409SSimon J. Gerraty * bit).
33*0957b409SSimon J. Gerraty */
34*0957b409SSimon J. Gerraty static size_t
asn1_int_length(const unsigned char * x,size_t xlen)35*0957b409SSimon J. Gerraty asn1_int_length(const unsigned char *x, size_t xlen)
36*0957b409SSimon J. Gerraty {
37*0957b409SSimon J. Gerraty while (xlen > 0 && *x == 0) {
38*0957b409SSimon J. Gerraty x ++;
39*0957b409SSimon J. Gerraty xlen --;
40*0957b409SSimon J. Gerraty }
41*0957b409SSimon J. Gerraty if (xlen == 0 || *x >= 0x80) {
42*0957b409SSimon J. Gerraty xlen ++;
43*0957b409SSimon J. Gerraty }
44*0957b409SSimon J. Gerraty return xlen;
45*0957b409SSimon J. Gerraty }
46*0957b409SSimon J. Gerraty
47*0957b409SSimon J. Gerraty /* see bearssl_ec.h */
48*0957b409SSimon J. Gerraty size_t
br_ecdsa_raw_to_asn1(void * sig,size_t sig_len)49*0957b409SSimon J. Gerraty br_ecdsa_raw_to_asn1(void *sig, size_t sig_len)
50*0957b409SSimon J. Gerraty {
51*0957b409SSimon J. Gerraty /*
52*0957b409SSimon J. Gerraty * Internal buffer is large enough to accommodate a signature
53*0957b409SSimon J. Gerraty * such that r and s fit on 125 bytes each (signed encoding),
54*0957b409SSimon J. Gerraty * meaning a curve order of up to 999 bits. This is the limit
55*0957b409SSimon J. Gerraty * that ensures "simple" length encodings.
56*0957b409SSimon J. Gerraty */
57*0957b409SSimon J. Gerraty unsigned char *buf;
58*0957b409SSimon J. Gerraty size_t hlen, rlen, slen, zlen, off;
59*0957b409SSimon J. Gerraty unsigned char tmp[257];
60*0957b409SSimon J. Gerraty
61*0957b409SSimon J. Gerraty buf = sig;
62*0957b409SSimon J. Gerraty if ((sig_len & 1) != 0) {
63*0957b409SSimon J. Gerraty return 0;
64*0957b409SSimon J. Gerraty }
65*0957b409SSimon J. Gerraty
66*0957b409SSimon J. Gerraty /*
67*0957b409SSimon J. Gerraty * Compute lengths for the two integers.
68*0957b409SSimon J. Gerraty */
69*0957b409SSimon J. Gerraty hlen = sig_len >> 1;
70*0957b409SSimon J. Gerraty rlen = asn1_int_length(buf, hlen);
71*0957b409SSimon J. Gerraty slen = asn1_int_length(buf + hlen, hlen);
72*0957b409SSimon J. Gerraty if (rlen > 125 || slen > 125) {
73*0957b409SSimon J. Gerraty return 0;
74*0957b409SSimon J. Gerraty }
75*0957b409SSimon J. Gerraty
76*0957b409SSimon J. Gerraty /*
77*0957b409SSimon J. Gerraty * SEQUENCE header.
78*0957b409SSimon J. Gerraty */
79*0957b409SSimon J. Gerraty tmp[0] = 0x30;
80*0957b409SSimon J. Gerraty zlen = rlen + slen + 4;
81*0957b409SSimon J. Gerraty if (zlen >= 0x80) {
82*0957b409SSimon J. Gerraty tmp[1] = 0x81;
83*0957b409SSimon J. Gerraty tmp[2] = zlen;
84*0957b409SSimon J. Gerraty off = 3;
85*0957b409SSimon J. Gerraty } else {
86*0957b409SSimon J. Gerraty tmp[1] = zlen;
87*0957b409SSimon J. Gerraty off = 2;
88*0957b409SSimon J. Gerraty }
89*0957b409SSimon J. Gerraty
90*0957b409SSimon J. Gerraty /*
91*0957b409SSimon J. Gerraty * First INTEGER (r).
92*0957b409SSimon J. Gerraty */
93*0957b409SSimon J. Gerraty tmp[off ++] = 0x02;
94*0957b409SSimon J. Gerraty tmp[off ++] = rlen;
95*0957b409SSimon J. Gerraty if (rlen > hlen) {
96*0957b409SSimon J. Gerraty tmp[off] = 0x00;
97*0957b409SSimon J. Gerraty memcpy(tmp + off + 1, buf, hlen);
98*0957b409SSimon J. Gerraty } else {
99*0957b409SSimon J. Gerraty memcpy(tmp + off, buf + hlen - rlen, rlen);
100*0957b409SSimon J. Gerraty }
101*0957b409SSimon J. Gerraty off += rlen;
102*0957b409SSimon J. Gerraty
103*0957b409SSimon J. Gerraty /*
104*0957b409SSimon J. Gerraty * Second INTEGER (s).
105*0957b409SSimon J. Gerraty */
106*0957b409SSimon J. Gerraty tmp[off ++] = 0x02;
107*0957b409SSimon J. Gerraty tmp[off ++] = slen;
108*0957b409SSimon J. Gerraty if (slen > hlen) {
109*0957b409SSimon J. Gerraty tmp[off] = 0x00;
110*0957b409SSimon J. Gerraty memcpy(tmp + off + 1, buf + hlen, hlen);
111*0957b409SSimon J. Gerraty } else {
112*0957b409SSimon J. Gerraty memcpy(tmp + off, buf + sig_len - slen, slen);
113*0957b409SSimon J. Gerraty }
114*0957b409SSimon J. Gerraty off += slen;
115*0957b409SSimon J. Gerraty
116*0957b409SSimon J. Gerraty /*
117*0957b409SSimon J. Gerraty * Return ASN.1 signature.
118*0957b409SSimon J. Gerraty */
119*0957b409SSimon J. Gerraty memcpy(sig, tmp, off);
120*0957b409SSimon J. Gerraty return off;
121*0957b409SSimon J. Gerraty }
122