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/* vim: set tabstop=8 shiftwidth=4 softtabstop=4 expandtab smarttab colorcolumn=80: */
/*
* Copyright 2016 Red Hat, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "misc.h"
#include "../hooks.h"
#include <jose/openssl.h>
#include <string.h>
declare_cleanup(EC_POINT)
declare_cleanup(EC_KEY)
declare_cleanup(BN_CTX)
static bool
jwk_prep_handles(jose_cfg_t *cfg, const json_t *jwk)
{
const char *alg = NULL;
if (json_unpack((json_t *) jwk, "{s:s}", "alg", &alg) == -1)
return false;
return strcmp(alg, "ECDH") == 0;
}
static bool
jwk_prep_execute(jose_cfg_t *cfg, json_t *jwk)
{
const char *crv = "P-521";
const char *alg = NULL;
const char *kty = NULL;
if (json_unpack(jwk, "{s:s,s?s,s?s}",
"alg", &alg, "crv", &crv, "kty", &kty) < 0)
return false;
if (strcmp(alg, "ECDH") != 0)
return false;
if (kty && strcmp(kty, "EC") != 0)
return false;
if (json_object_set_new(jwk, "kty", json_string("EC")) < 0)
return false;
if (json_object_set_new(jwk, "crv", json_string(crv)) < 0)
return false;
return true;
}
static const char *
alg_exch_sug(const jose_hook_alg_t *alg, jose_cfg_t *cfg,
const json_t *prv, const json_t *pub)
{
const char *crva = NULL;
const char *crvb = NULL;
const char *ktya = NULL;
const char *ktyb = NULL;
if (json_unpack((json_t *) prv, "{s:s,s:s}", "kty", &ktya, "crv", &crva) < 0)
return NULL;
if (json_unpack((json_t *) pub, "{s:s,s:s}", "kty", &ktyb, "crv", &crvb) < 0)
return NULL;
if (strcmp("EC", ktya) != 0 || strcmp("EC", ktyb) != 0)
return NULL;
if (strcmp(crva, crvb) != 0)
return NULL;
if (str2enum(crva, "P-256", "P-384", "P-521", NULL) == SIZE_MAX)
return NULL;
return "ECDH";
}
static json_t *
alg_exch_exc(const jose_hook_alg_t *alg, jose_cfg_t *cfg,
const json_t *prv, const json_t *pub)
{
openssl_auto(EC_KEY) *lcl = NULL;
openssl_auto(EC_KEY) *rem = NULL;
openssl_auto(BN_CTX) *bnc = NULL;
openssl_auto(EC_POINT) *p = NULL;
const EC_GROUP *grp = NULL;
bnc = BN_CTX_new();
if (!bnc)
return NULL;
lcl = jose_openssl_jwk_to_EC_KEY(cfg, prv);
if (!lcl)
return NULL;
rem = jose_openssl_jwk_to_EC_KEY(cfg, pub);
if (!rem)
return NULL;
grp = EC_KEY_get0_group(lcl);
if (EC_GROUP_cmp(grp, EC_KEY_get0_group(rem), bnc) != 0)
return NULL;
p = EC_POINT_new(grp);
if (!p)
return NULL;
if (EC_POINT_mul(grp, p, NULL, EC_KEY_get0_public_key(rem),
EC_KEY_get0_private_key(lcl), bnc) <= 0)
return NULL;
return jose_openssl_jwk_from_EC_POINT(cfg, EC_KEY_get0_group(rem), p, NULL);
}
static void __attribute__((constructor))
constructor(void)
{
static jose_hook_jwk_t jwk = {
.kind = JOSE_HOOK_JWK_KIND_PREP,
.prep.handles = jwk_prep_handles,
.prep.execute = jwk_prep_execute
};
static jose_hook_alg_t ecdh[] = {
{ .name = "ECDH",
.kind = JOSE_HOOK_ALG_KIND_EXCH,
.exch.prm = "deriveKey",
.exch.sug = alg_exch_sug,
.exch.exc = alg_exch_exc },
{}
};
jose_hook_jwk_push(&jwk);
for (size_t i = 0; ecdh[i].name; i++)
jose_hook_alg_push(&ecdh[i]);
}
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