182 lines
3.9 KiB
C
Executable file
182 lines
3.9 KiB
C
Executable file
/* $OpenBSD: ssl_kex.c,v 1.2 2020/04/18 14:07:56 jsing Exp $ */
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/*
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* Copyright (c) 2020 Joel Sing <jsing@openbsd.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <stdlib.h>
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#include <openssl/ec.h>
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#include <openssl/ecdh.h>
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#include <openssl/evp.h>
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#include <openssl/objects.h>
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#include "bytestring.h"
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int
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ssl_kex_dummy_ecdhe_x25519(EVP_PKEY *pkey)
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{
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EC_GROUP *group = NULL;
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EC_POINT *point = NULL;
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EC_KEY *ec_key = NULL;
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BIGNUM *order = NULL;
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int ret = 0;
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/* Fudge up an EC_KEY that looks like X25519... */
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if ((group = EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1)) == NULL)
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goto err;
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if ((point = EC_POINT_new(group)) == NULL)
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goto err;
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if ((order = BN_new()) == NULL)
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goto err;
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if (!BN_set_bit(order, 252))
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goto err;
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if (!EC_GROUP_set_generator(group, point, order, NULL))
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goto err;
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EC_GROUP_set_curve_name(group, NID_X25519);
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if ((ec_key = EC_KEY_new()) == NULL)
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goto err;
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if (!EC_KEY_set_group(ec_key, group))
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goto err;
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if (!EVP_PKEY_set1_EC_KEY(pkey, ec_key))
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goto err;
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ret = 1;
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err:
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EC_GROUP_free(group);
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EC_POINT_free(point);
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EC_KEY_free(ec_key);
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BN_free(order);
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return ret;
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}
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int
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ssl_kex_generate_ecdhe_ecp(EC_KEY *ecdh, int nid)
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{
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EC_GROUP *group;
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int ret = 0;
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if ((group = EC_GROUP_new_by_curve_name(nid)) == NULL)
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goto err;
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if (!EC_KEY_set_group(ecdh, group))
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goto err;
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if (!EC_KEY_generate_key(ecdh))
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goto err;
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ret = 1;
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err:
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EC_GROUP_free(group);
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return ret;
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}
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int
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ssl_kex_public_ecdhe_ecp(EC_KEY *ecdh, CBB *cbb)
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{
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const EC_GROUP *group;
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const EC_POINT *point;
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uint8_t *ecp;
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size_t ecp_len;
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int ret = 0;
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if ((group = EC_KEY_get0_group(ecdh)) == NULL)
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goto err;
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if ((point = EC_KEY_get0_public_key(ecdh)) == NULL)
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goto err;
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if ((ecp_len = EC_POINT_point2oct(group, point,
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POINT_CONVERSION_UNCOMPRESSED, NULL, 0, NULL)) == 0)
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goto err;
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if (!CBB_add_space(cbb, &ecp, ecp_len))
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goto err;
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if ((EC_POINT_point2oct(group, point, POINT_CONVERSION_UNCOMPRESSED,
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ecp, ecp_len, NULL)) == 0)
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goto err;
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ret = 1;
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err:
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return ret;
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}
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int
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ssl_kex_peer_public_ecdhe_ecp(EC_KEY *ecdh, int nid, CBS *cbs)
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{
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EC_GROUP *group = NULL;
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EC_POINT *point = NULL;
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int ret = 0;
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if ((group = EC_GROUP_new_by_curve_name(nid)) == NULL)
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goto err;
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if (!EC_KEY_set_group(ecdh, group))
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goto err;
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if ((point = EC_POINT_new(group)) == NULL)
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goto err;
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if (EC_POINT_oct2point(group, point, CBS_data(cbs), CBS_len(cbs),
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NULL) == 0)
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goto err;
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if (!EC_KEY_set_public_key(ecdh, point))
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goto err;
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ret = 1;
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err:
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EC_GROUP_free(group);
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EC_POINT_free(point);
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return ret;
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}
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int
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ssl_kex_derive_ecdhe_ecp(EC_KEY *ecdh, EC_KEY *ecdh_peer,
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uint8_t **shared_key, size_t *shared_key_len)
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{
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const EC_POINT *point;
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uint8_t *sk = NULL;
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int sk_len = 0;
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int ret = 0;
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if (!EC_GROUP_check(EC_KEY_get0_group(ecdh), NULL))
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goto err;
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if (!EC_GROUP_check(EC_KEY_get0_group(ecdh_peer), NULL))
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goto err;
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if ((point = EC_KEY_get0_public_key(ecdh_peer)) == NULL)
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goto err;
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if ((sk_len = ECDH_size(ecdh)) <= 0)
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goto err;
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if ((sk = calloc(1, sk_len)) == NULL)
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goto err;
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if (ECDH_compute_key(sk, sk_len, point, ecdh, NULL) <= 0)
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goto err;
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*shared_key = sk;
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*shared_key_len = sk_len;
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sk = NULL;
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ret = 1;
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err:
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freezero(sk, sk_len);
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return ret;
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}
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