1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
|
/* $OpenBSD: bufec.c,v 1.2 2013/05/17 00:13:13 djm Exp $ */
/*
* Copyright (c) 2010 Damien Miller <djm@mindrot.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <openssl/bn.h>
#include <openssl/ec.h>
#include <string.h>
#include <stdarg.h>
#include "xmalloc.h"
#include "buffer.h"
#include "log.h"
#include "misc.h"
/*
* Maximum supported EC GFp field length is 528 bits. SEC1 uncompressed
* encoding represents this as two bitstring points that should each
* be no longer than the field length, SEC1 specifies a 1 byte
* point type header.
* Being paranoid here may insulate us to parsing problems in
* EC_POINT_oct2point.
*/
#define BUFFER_MAX_ECPOINT_LEN ((528*2 / 8) + 1)
/*
* Append an EC_POINT to the buffer as a string containing a SEC1 encoded
* uncompressed point. Fortunately OpenSSL handles the gory details for us.
*/
int
buffer_put_ecpoint_ret(Buffer *buffer, const EC_GROUP *curve,
const EC_POINT *point)
{
u_char *buf = NULL;
size_t len;
BN_CTX *bnctx;
int ret = -1;
/* Determine length */
if ((bnctx = BN_CTX_new()) == NULL)
fatal("%s: BN_CTX_new failed", __func__);
len = EC_POINT_point2oct(curve, point, POINT_CONVERSION_UNCOMPRESSED,
NULL, 0, bnctx);
if (len > BUFFER_MAX_ECPOINT_LEN) {
error("%s: giant EC point: len = %lu (max %u)",
__func__, (u_long)len, BUFFER_MAX_ECPOINT_LEN);
goto out;
}
/* Convert */
buf = xmalloc(len);
if (EC_POINT_point2oct(curve, point, POINT_CONVERSION_UNCOMPRESSED,
buf, len, bnctx) != len) {
error("%s: EC_POINT_point2oct length mismatch", __func__);
goto out;
}
/* Append */
buffer_put_string(buffer, buf, len);
ret = 0;
out:
if (buf != NULL) {
bzero(buf, len);
free(buf);
}
BN_CTX_free(bnctx);
return ret;
}
void
buffer_put_ecpoint(Buffer *buffer, const EC_GROUP *curve,
const EC_POINT *point)
{
if (buffer_put_ecpoint_ret(buffer, curve, point) == -1)
fatal("%s: buffer error", __func__);
}
int
buffer_get_ecpoint_ret(Buffer *buffer, const EC_GROUP *curve,
EC_POINT *point)
{
u_char *buf;
u_int len;
BN_CTX *bnctx;
int ret = -1;
if ((buf = buffer_get_string_ret(buffer, &len)) == NULL) {
error("%s: invalid point", __func__);
return -1;
}
if ((bnctx = BN_CTX_new()) == NULL)
fatal("%s: BN_CTX_new failed", __func__);
if (len > BUFFER_MAX_ECPOINT_LEN) {
error("%s: EC_POINT too long: %u > max %u", __func__,
len, BUFFER_MAX_ECPOINT_LEN);
goto out;
}
if (len == 0) {
error("%s: EC_POINT buffer is empty", __func__);
goto out;
}
if (buf[0] != POINT_CONVERSION_UNCOMPRESSED) {
error("%s: EC_POINT is in an incorrect form: "
"0x%02x (want 0x%02x)", __func__, buf[0],
POINT_CONVERSION_UNCOMPRESSED);
goto out;
}
if (EC_POINT_oct2point(curve, point, buf, len, bnctx) != 1) {
error("buffer_get_bignum2_ret: BN_bin2bn failed");
goto out;
}
/* EC_POINT_oct2point verifies that the point is on the curve for us */
ret = 0;
out:
BN_CTX_free(bnctx);
bzero(buf, len);
free(buf);
return ret;
}
void
buffer_get_ecpoint(Buffer *buffer, const EC_GROUP *curve,
EC_POINT *point)
{
if (buffer_get_ecpoint_ret(buffer, curve, point) == -1)
fatal("%s: buffer error", __func__);
}
|
