1 /* $OpenBSD: bufec.c,v 1.1 2010/08/31 11:54:45 djm Exp $ */
3 * Copyright (c) 2010 Damien Miller <djm@mindrot.org>
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
20 #ifdef OPENSSL_HAS_ECC
22 #include <sys/types.h>
24 #include <openssl/bn.h>
25 #include <openssl/ec.h>
36 * Maximum supported EC GFp field length is 528 bits. SEC1 uncompressed
37 * encoding represents this as two bitstring points that should each
38 * be no longer than the field length, SEC1 specifies a 1 byte
40 * Being paranoid here may insulate us to parsing problems in
43 #define BUFFER_MAX_ECPOINT_LEN ((528*2 / 8) + 1)
46 * Append an EC_POINT to the buffer as a string containing a SEC1 encoded
47 * uncompressed point. Fortunately OpenSSL handles the gory details for us.
50 buffer_put_ecpoint_ret(Buffer *buffer, const EC_GROUP *curve,
51 const EC_POINT *point)
58 /* Determine length */
59 if ((bnctx = BN_CTX_new()) == NULL)
60 fatal("%s: BN_CTX_new failed", __func__);
61 len = EC_POINT_point2oct(curve, point, POINT_CONVERSION_UNCOMPRESSED,
63 if (len > BUFFER_MAX_ECPOINT_LEN) {
64 error("%s: giant EC point: len = %lu (max %u)",
65 __func__, (u_long)len, BUFFER_MAX_ECPOINT_LEN);
70 if (EC_POINT_point2oct(curve, point, POINT_CONVERSION_UNCOMPRESSED,
71 buf, len, bnctx) != len) {
72 error("%s: EC_POINT_point2oct length mismatch", __func__);
76 buffer_put_string(buffer, buf, len);
88 buffer_put_ecpoint(Buffer *buffer, const EC_GROUP *curve,
89 const EC_POINT *point)
91 if (buffer_put_ecpoint_ret(buffer, curve, point) == -1)
92 fatal("%s: buffer error", __func__);
96 buffer_get_ecpoint_ret(Buffer *buffer, const EC_GROUP *curve,
104 if ((buf = buffer_get_string_ret(buffer, &len)) == NULL) {
105 error("%s: invalid point", __func__);
108 if ((bnctx = BN_CTX_new()) == NULL)
109 fatal("%s: BN_CTX_new failed", __func__);
110 if (len > BUFFER_MAX_ECPOINT_LEN) {
111 error("%s: EC_POINT too long: %u > max %u", __func__,
112 len, BUFFER_MAX_ECPOINT_LEN);
116 error("%s: EC_POINT buffer is empty", __func__);
119 if (buf[0] != POINT_CONVERSION_UNCOMPRESSED) {
120 error("%s: EC_POINT is in an incorrect form: "
121 "0x%02x (want 0x%02x)", __func__, buf[0],
122 POINT_CONVERSION_UNCOMPRESSED);
125 if (EC_POINT_oct2point(curve, point, buf, len, bnctx) != 1) {
126 error("buffer_get_bignum2_ret: BN_bin2bn failed");
129 /* EC_POINT_oct2point verifies that the point is on the curve for us */
139 buffer_get_ecpoint(Buffer *buffer, const EC_GROUP *curve,
142 if (buffer_get_ecpoint_ret(buffer, curve, point) == -1)
143 fatal("%s: buffer error", __func__);
146 #endif /* OPENSSL_HAS_ECC */