Annotation of src/usr.bin/ssh/bufec.c, Revision 1.1
1.1 ! djm 1: /* $OpenBSD$ */
! 2: /*
! 3: * Copyright (c) 2010 Damien Miller <djm@mindrot.org>
! 4: *
! 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.
! 8: *
! 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.
! 16: */
! 17: #include <sys/types.h>
! 18:
! 19: #include <openssl/bn.h>
! 20: #include <openssl/ec.h>
! 21:
! 22: #include <string.h>
! 23: #include <stdarg.h>
! 24:
! 25: #include "xmalloc.h"
! 26: #include "buffer.h"
! 27: #include "log.h"
! 28: #include "misc.h"
! 29:
! 30: /*
! 31: * Maximum supported EC GFp field length is 528 bits. SEC1 uncompressed
! 32: * encoding represents this as two bitstring points that should each
! 33: * be no longer than the field length, SEC1 specifies a 1 byte
! 34: * point type header.
! 35: * Being paranoid here may insulate us to parsing problems in
! 36: * EC_POINT_oct2point.
! 37: */
! 38: #define BUFFER_MAX_ECPOINT_LEN ((528*2 / 8) + 1)
! 39:
! 40: /*
! 41: * Append an EC_POINT to the buffer as a string containing a SEC1 encoded
! 42: * uncompressed point. Fortunately OpenSSL handles the gory details for us.
! 43: */
! 44: int
! 45: buffer_put_ecpoint_ret(Buffer *buffer, const EC_GROUP *curve,
! 46: const EC_POINT *point)
! 47: {
! 48: u_char *buf = NULL;
! 49: size_t len;
! 50: BN_CTX *bnctx;
! 51: int ret = -1;
! 52:
! 53: /* Determine length */
! 54: if ((bnctx = BN_CTX_new()) == NULL)
! 55: fatal("%s: BN_CTX_new failed", __func__);
! 56: len = EC_POINT_point2oct(curve, point, POINT_CONVERSION_UNCOMPRESSED,
! 57: NULL, 0, bnctx);
! 58: if (len > BUFFER_MAX_ECPOINT_LEN) {
! 59: error("%s: giant EC point: len = %lu (max %u)",
! 60: __func__, (u_long)len, BUFFER_MAX_ECPOINT_LEN);
! 61: goto out;
! 62: }
! 63: /* Convert */
! 64: buf = xmalloc(len);
! 65: if (EC_POINT_point2oct(curve, point, POINT_CONVERSION_UNCOMPRESSED,
! 66: buf, len, bnctx) != len) {
! 67: error("%s: EC_POINT_point2oct length mismatch", __func__);
! 68: goto out;
! 69: }
! 70: /* Append */
! 71: buffer_put_string(buffer, buf, len);
! 72: ret = 0;
! 73: out:
! 74: if (buf != NULL) {
! 75: bzero(buf, len);
! 76: xfree(buf);
! 77: }
! 78: BN_CTX_free(bnctx);
! 79: return ret;
! 80: }
! 81:
! 82: void
! 83: buffer_put_ecpoint(Buffer *buffer, const EC_GROUP *curve,
! 84: const EC_POINT *point)
! 85: {
! 86: if (buffer_put_ecpoint_ret(buffer, curve, point) == -1)
! 87: fatal("%s: buffer error", __func__);
! 88: }
! 89:
! 90: int
! 91: buffer_get_ecpoint_ret(Buffer *buffer, const EC_GROUP *curve,
! 92: EC_POINT *point)
! 93: {
! 94: u_char *buf;
! 95: u_int len;
! 96: BN_CTX *bnctx;
! 97: int ret = -1;
! 98:
! 99: if ((buf = buffer_get_string_ret(buffer, &len)) == NULL) {
! 100: error("%s: invalid point", __func__);
! 101: return -1;
! 102: }
! 103: if ((bnctx = BN_CTX_new()) == NULL)
! 104: fatal("%s: BN_CTX_new failed", __func__);
! 105: if (len > BUFFER_MAX_ECPOINT_LEN) {
! 106: error("%s: EC_POINT too long: %u > max %u", __func__,
! 107: len, BUFFER_MAX_ECPOINT_LEN);
! 108: goto out;
! 109: }
! 110: if (len == 0) {
! 111: error("%s: EC_POINT buffer is empty", __func__);
! 112: goto out;
! 113: }
! 114: if (buf[0] != POINT_CONVERSION_UNCOMPRESSED) {
! 115: error("%s: EC_POINT is in an incorrect form: "
! 116: "0x%02x (want 0x%02x)", __func__, buf[0],
! 117: POINT_CONVERSION_UNCOMPRESSED);
! 118: goto out;
! 119: }
! 120: if (EC_POINT_oct2point(curve, point, buf, len, bnctx) != 1) {
! 121: error("buffer_get_bignum2_ret: BN_bin2bn failed");
! 122: goto out;
! 123: }
! 124: /* EC_POINT_oct2point verifies that the point is on the curve for us */
! 125: ret = 0;
! 126: out:
! 127: BN_CTX_free(bnctx);
! 128: bzero(buf, len);
! 129: xfree(buf);
! 130: return ret;
! 131: }
! 132:
! 133: void
! 134: buffer_get_ecpoint(Buffer *buffer, const EC_GROUP *curve,
! 135: EC_POINT *point)
! 136: {
! 137: if (buffer_get_ecpoint_ret(buffer, curve, point) == -1)
! 138: fatal("%s: buffer error", __func__);
! 139: }
! 140:
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