[thirdparty/openssl.git] / crypto / evp / exchange.c

/*
 * Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <openssl/crypto.h>
#include <openssl/evp.h>
#include <openssl/err.h>
#include "internal/refcount.h"
#include "internal/evp_int.h"
#include "internal/provider.h"
#include "evp_locl.h"

static EVP_KEYEXCH *evp_keyexch_new(OSSL_PROVIDER *prov)
{
    EVP_KEYEXCH *exchange = OPENSSL_zalloc(sizeof(EVP_KEYEXCH));

    exchange->lock = CRYPTO_THREAD_lock_new();
    if (exchange->lock == NULL) {
        OPENSSL_free(exchange);
        return NULL;
    }
    exchange->prov = prov;
    ossl_provider_up_ref(prov);
    exchange->refcnt = 1;

    return exchange;
}

static void *evp_keyexch_from_dispatch(const OSSL_DISPATCH *fns,
                                       OSSL_PROVIDER *prov)
{
    EVP_KEYEXCH *exchange = NULL;
    int fncnt = 0;

    if ((exchange = evp_keyexch_new(prov)) == NULL)
        return NULL;

    for (; fns->function_id != 0; fns++) {
        switch (fns->function_id) {
        case OSSL_FUNC_KEYEXCH_NEWCTX:
            if (exchange->newctx != NULL)
                break;
            exchange->newctx = OSSL_get_OP_keyexch_newctx(fns);
            fncnt++;
            break;
        case OSSL_FUNC_KEYEXCH_INIT:
            if (exchange->init != NULL)
                break;
            exchange->init = OSSL_get_OP_keyexch_init(fns);
            fncnt++;
            break;
        case OSSL_FUNC_KEYEXCH_SET_PEER:
            if (exchange->set_peer != NULL)
                break;
            exchange->set_peer = OSSL_get_OP_keyexch_set_peer(fns);
            break;
        case OSSL_FUNC_KEYEXCH_DERIVE:
            if (exchange->derive != NULL)
                break;
            exchange->derive = OSSL_get_OP_keyexch_derive(fns);
            fncnt++;
            break;
        case OSSL_FUNC_KEYEXCH_FREECTX:
            if (exchange->freectx != NULL)
                break;
            exchange->freectx = OSSL_get_OP_keyexch_freectx(fns);
            fncnt++;
            break;
        case OSSL_FUNC_KEYEXCH_DUPCTX:
            if (exchange->dupctx != NULL)
                break;
            exchange->dupctx = OSSL_get_OP_keyexch_dupctx(fns);
            break;
        }
    }
    if (fncnt != 4) {
        /*
         * In order to be a consistent set of functions we must have at least
         * a complete set of "exchange" functions: init, derive, newctx,
         * and freectx. The dupctx and set_peer functions are optional.
         */
        EVP_KEYEXCH_free(exchange);
        EVPerr(EVP_F_EVP_KEYEXCH_FROM_DISPATCH,
               EVP_R_INVALID_PROVIDER_FUNCTIONS);
        return NULL;
    }

    return exchange;
}

void EVP_KEYEXCH_free(EVP_KEYEXCH *exchange)
{
    if (exchange != NULL) {
        int i;

        CRYPTO_DOWN_REF(&exchange->refcnt, &i, exchange->lock);
        if (i > 0)
            return;
        ossl_provider_free(exchange->prov);
        CRYPTO_THREAD_lock_free(exchange->lock);
        OPENSSL_free(exchange);
    }
}

int EVP_KEYEXCH_up_ref(EVP_KEYEXCH *exchange)
{
    int ref = 0;

    CRYPTO_UP_REF(&exchange->refcnt, &ref, exchange->lock);
    return 1;
}

EVP_KEYEXCH *EVP_KEYEXCH_fetch(OPENSSL_CTX *ctx, const char *algorithm,
                               const char *properties)
{
    return evp_generic_fetch(ctx, OSSL_OP_KEYEXCH, algorithm, properties,
                             evp_keyexch_from_dispatch,
                             (int (*)(void *))EVP_KEYEXCH_up_ref,
                             (void (*)(void *))EVP_KEYEXCH_free);
}

int EVP_PKEY_derive_init_ex(EVP_PKEY_CTX *ctx, EVP_KEYEXCH *exchange)
{
    int ret;
    OSSL_PARAM *param = NULL;
    size_t paramsz = 0;

    ctx->operation = EVP_PKEY_OP_DERIVE;

    if (ctx->engine != NULL)
        goto legacy;

    if (exchange != NULL) {
        if (!EVP_KEYEXCH_up_ref(exchange))
            goto err;
    } else {
        int nid = ctx->pkey != NULL ? ctx->pkey->type : ctx->pmeth->pkey_id;

        /*
         * TODO(3.0): Check for legacy handling. Remove this once all all
         * algorithms are moved to providers.
         */
        if (ctx->pkey != NULL) {
            switch (ctx->pkey->type) {
            case EVP_PKEY_DH:
                break;
            default:
                goto legacy;
            }
            exchange = EVP_KEYEXCH_fetch(NULL, OBJ_nid2sn(nid), NULL);
        } else {
            goto legacy;
        }

        if (exchange == NULL) {
            EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX, EVP_R_INITIALIZATION_ERROR);
            goto err;
        }
    }

    if (ctx->exchprovctx != NULL && ctx->exchange != NULL)
        ctx->exchange->freectx(ctx->exchprovctx);
    EVP_KEYEXCH_free(ctx->exchange);
    ctx->exchange = exchange;
    if (ctx->pkey != NULL) {
        param = evp_pkey_to_param(ctx->pkey, &paramsz);
        if (param == NULL) {
            EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX, EVP_R_INITIALIZATION_ERROR);
            goto err;
        }
    }
    ctx->exchprovctx = exchange->newctx(ossl_provider_ctx(exchange->prov));
    if (ctx->exchprovctx == NULL) {
        OPENSSL_secure_clear_free(param, paramsz);
        EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX, EVP_R_INITIALIZATION_ERROR);
        goto err;
    }
    ret = exchange->init(ctx->exchprovctx, param);
    /*
     * TODO(3.0): Really we should detect whether to call OPENSSL_free or
     * OPENSSL_secure_clear_free based on the presence of a private key or not.
     * Since we always expect a private key to be present we just call
     * OPENSSL_secure_clear_free for now.
     */
    OPENSSL_secure_clear_free(param, paramsz);

    return ret ? 1 : 0;
 err:
    ctx->operation = EVP_PKEY_OP_UNDEFINED;
    return 0;

 legacy:
    if (ctx == NULL || ctx->pmeth == NULL || ctx->pmeth->derive == NULL) {
        EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX,
               EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
        return -2;
    }

    if (ctx->pmeth->derive_init == NULL)
        return 1;
    ret = ctx->pmeth->derive_init(ctx);
    if (ret <= 0)
        ctx->operation = EVP_PKEY_OP_UNDEFINED;
    return ret;
}

int EVP_PKEY_derive_init(EVP_PKEY_CTX *ctx)
{
    return EVP_PKEY_derive_init_ex(ctx, NULL);
}

int EVP_PKEY_derive_set_peer(EVP_PKEY_CTX *ctx, EVP_PKEY *peer)
{
    int ret;
    OSSL_PARAM *param = NULL;

    if (ctx == NULL) {
        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER,
               EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
        return -2;
    }

    if (ctx->exchprovctx == NULL)
        goto legacy;

    if (ctx->operation != EVP_PKEY_OP_DERIVE) {
        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER,
               EVP_R_OPERATON_NOT_INITIALIZED);
        return -1;
    }

    if (ctx->exchange->set_peer == NULL) {
        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER,
               EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
        return -2;
    }

    param = evp_pkey_to_param(peer, NULL);
    if (param == NULL) {
        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER, ERR_R_INTERNAL_ERROR);
        return 0;
    }
    ret = ctx->exchange->set_peer(ctx->exchprovctx, param);
    /*
     * TODO(3.0): Really we should detect whether to call OPENSSL_free or
     * OPENSSL_secure_clear_free based on the presence of a private key or not.
     * Since we always expect a public key to be present we just call
     * OPENSSL_free for now.
     */
    OPENSSL_free(param);

    return ret;

 legacy:
    if (ctx->pmeth == NULL
        || !(ctx->pmeth->derive != NULL
             || ctx->pmeth->encrypt != NULL
             || ctx->pmeth->decrypt != NULL)
        || ctx->pmeth->ctrl == NULL) {
        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER,
               EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
        return -2;
    }
    if (ctx->operation != EVP_PKEY_OP_DERIVE
        && ctx->operation != EVP_PKEY_OP_ENCRYPT
        && ctx->operation != EVP_PKEY_OP_DECRYPT) {
        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER,
               EVP_R_OPERATON_NOT_INITIALIZED);
        return -1;
    }

    ret = ctx->pmeth->ctrl(ctx, EVP_PKEY_CTRL_PEER_KEY, 0, peer);

    if (ret <= 0)
        return ret;

    if (ret == 2)
        return 1;

    if (ctx->pkey == NULL) {
        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER, EVP_R_NO_KEY_SET);
        return -1;
    }

    if (ctx->pkey->type != peer->type) {
        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER, EVP_R_DIFFERENT_KEY_TYPES);
        return -1;
    }

    /*
     * For clarity.  The error is if parameters in peer are
     * present (!missing) but don't match.  EVP_PKEY_cmp_parameters may return
     * 1 (match), 0 (don't match) and -2 (comparison is not defined).  -1
     * (different key types) is impossible here because it is checked earlier.
     * -2 is OK for us here, as well as 1, so we can check for 0 only.
     */
    if (!EVP_PKEY_missing_parameters(peer) &&
        !EVP_PKEY_cmp_parameters(ctx->pkey, peer)) {
        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER, EVP_R_DIFFERENT_PARAMETERS);
        return -1;
    }

    EVP_PKEY_free(ctx->peerkey);
    ctx->peerkey = peer;

    ret = ctx->pmeth->ctrl(ctx, EVP_PKEY_CTRL_PEER_KEY, 1, peer);

    if (ret <= 0) {
        ctx->peerkey = NULL;
        return ret;
    }

    EVP_PKEY_up_ref(peer);
    return 1;
}

int EVP_PKEY_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *pkeylen)
{
    int ret;

    if (ctx == NULL) {
        EVPerr(EVP_F_EVP_PKEY_DERIVE,
               EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
        return -2;
    }

    if (ctx->operation != EVP_PKEY_OP_DERIVE) {
        EVPerr(EVP_F_EVP_PKEY_DERIVE, EVP_R_OPERATON_NOT_INITIALIZED);
        return -1;
    }

    if (ctx->exchprovctx == NULL)
        goto legacy;

    ret = ctx->exchange->derive(ctx->exchprovctx, key, pkeylen, SIZE_MAX);

    return ret;
 legacy:
    if (ctx ==  NULL || ctx->pmeth == NULL || ctx->pmeth->derive == NULL) {
        EVPerr(EVP_F_EVP_PKEY_DERIVE,
               EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
        return -2;
    }

    M_check_autoarg(ctx, key, pkeylen, EVP_F_EVP_PKEY_DERIVE)
        return ctx->pmeth->derive(ctx, key, pkeylen);
}
Commit	Line	Data
ff64702b MC	1	/*
	2	* Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
	3	*
	4	* Licensed under the Apache License 2.0 (the "License"). You may not use
	5	* this file except in compliance with the License. You can obtain a copy
	6	* in the file LICENSE in the source distribution or at
	7	* https://www.openssl.org/source/license.html
	8	*/
	9
	10	#include <openssl/crypto.h>
	11	#include <openssl/evp.h>
	12	#include <openssl/err.h>
	13	#include "internal/refcount.h"
	14	#include "internal/evp_int.h"
	15	#include "internal/provider.h"
	16	#include "evp_locl.h"
	17
	18	static EVP_KEYEXCH evp_keyexch_new(OSSL_PROVIDER prov)
	19	{
	20	EVP_KEYEXCH *exchange = OPENSSL_zalloc(sizeof(EVP_KEYEXCH));
	21
	22	exchange->lock = CRYPTO_THREAD_lock_new();
	23	if (exchange->lock == NULL) {
	24	OPENSSL_free(exchange);
	25	return NULL;
	26	}
	27	exchange->prov = prov;
	28	ossl_provider_up_ref(prov);
	29	exchange->refcnt = 1;
	30
	31	return exchange;
	32	}
	33
	34	static void evp_keyexch_from_dispatch(const OSSL_DISPATCH fns,
	35	OSSL_PROVIDER *prov)
	36	{
	37	EVP_KEYEXCH *exchange = NULL;
	38	int fncnt = 0;
	39
	40	if ((exchange = evp_keyexch_new(prov)) == NULL)
	41	return NULL;
	42
	43	for (; fns->function_id != 0; fns++) {
	44	switch (fns->function_id) {
	45	case OSSL_FUNC_KEYEXCH_NEWCTX:
	46	if (exchange->newctx != NULL)
	47	break;
	48	exchange->newctx = OSSL_get_OP_keyexch_newctx(fns);
	49	fncnt++;
	50	break;
	51	case OSSL_FUNC_KEYEXCH_INIT:
	52	if (exchange->init != NULL)
	53	break;
	54	exchange->init = OSSL_get_OP_keyexch_init(fns);
	55	fncnt++;
	56	break;
	57	case OSSL_FUNC_KEYEXCH_SET_PEER:
	58	if (exchange->set_peer != NULL)
	59	break;
	60	exchange->set_peer = OSSL_get_OP_keyexch_set_peer(fns);
	61	break;
	62	case OSSL_FUNC_KEYEXCH_DERIVE:
	63	if (exchange->derive != NULL)
	64	break;
65	exchange->derive = OSSL_get_OP_keyexch_derive(fns);
66	fncnt++;
67	break;
68	case OSSL_FUNC_KEYEXCH_FREECTX:
69	if (exchange->freectx != NULL)
70	break;
71	exchange->freectx = OSSL_get_OP_keyexch_freectx(fns);
72	fncnt++;
73	break;
74	case OSSL_FUNC_KEYEXCH_DUPCTX:
75	if (exchange->dupctx != NULL)
76	break;
77	exchange->dupctx = OSSL_get_OP_keyexch_dupctx(fns);
78	break;
79	}
80	}
81	if (fncnt != 4) {
82	/*
83	* In order to be a consistent set of functions we must have at least
84	* a complete set of "exchange" functions: init, derive, newctx,
85	* and freectx. The dupctx and set_peer functions are optional.
86	*/
87	EVP_KEYEXCH_free(exchange);
88	EVPerr(EVP_F_EVP_KEYEXCH_FROM_DISPATCH,
89	EVP_R_INVALID_PROVIDER_FUNCTIONS);
90	return NULL;
91	}
92
93	return exchange;
94	}
95
96	void EVP_KEYEXCH_free(EVP_KEYEXCH *exchange)
97	{
98	if (exchange != NULL) {
99	int i;
100
101	CRYPTO_DOWN_REF(&exchange->refcnt, &i, exchange->lock);
102	if (i > 0)
103	return;
104	ossl_provider_free(exchange->prov);
105	CRYPTO_THREAD_lock_free(exchange->lock);
106	OPENSSL_free(exchange);
107	}
108	}
109
110	int EVP_KEYEXCH_up_ref(EVP_KEYEXCH *exchange)
111	{
112	int ref = 0;
113
114	CRYPTO_UP_REF(&exchange->refcnt, &ref, exchange->lock);
115	return 1;
116	}
117
118	EVP_KEYEXCH EVP_KEYEXCH_fetch(OPENSSL_CTX ctx, const char *algorithm,
119	const char *properties)
120	{
121	return evp_generic_fetch(ctx, OSSL_OP_KEYEXCH, algorithm, properties,
122	evp_keyexch_from_dispatch,
123	(int ()(void ))EVP_KEYEXCH_up_ref,
124	(void ()(void ))EVP_KEYEXCH_free);
125	}
126
127	int EVP_PKEY_derive_init_ex(EVP_PKEY_CTX ctx, EVP_KEYEXCH exchange)
128	{
129	int ret;
130	OSSL_PARAM *param = NULL;
131	size_t paramsz = 0;
132
133	ctx->operation = EVP_PKEY_OP_DERIVE;
134
135	if (ctx->engine != NULL)
136	goto legacy;
137
138	if (exchange != NULL) {
139	if (!EVP_KEYEXCH_up_ref(exchange))
140	goto err;
141	} else {
142	int nid = ctx->pkey != NULL ? ctx->pkey->type : ctx->pmeth->pkey_id;
143
144	/*
145	* TODO(3.0): Check for legacy handling. Remove this once all all
146	* algorithms are moved to providers.
147	*/
148	if (ctx->pkey != NULL) {
149	switch (ctx->pkey->type) {
ff64702b MC	150	case EVP_PKEY_DH:
ff64702b MC	151	break;
ff64702b MC	152	default:
	153	goto legacy;
	154	}
	155	exchange = EVP_KEYEXCH_fetch(NULL, OBJ_nid2sn(nid), NULL);
	156	} else {
	157	goto legacy;
	158	}
	159
	160	if (exchange == NULL) {
	161	EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX, EVP_R_INITIALIZATION_ERROR);
	162	goto err;
	163	}
	164	}
	165
	166	if (ctx->exchprovctx != NULL && ctx->exchange != NULL)
	167	ctx->exchange->freectx(ctx->exchprovctx);
	168	EVP_KEYEXCH_free(ctx->exchange);
	169	ctx->exchange = exchange;
	170	if (ctx->pkey != NULL) {
	171	param = evp_pkey_to_param(ctx->pkey, &paramsz);
	172	if (param == NULL) {
	173	EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX, EVP_R_INITIALIZATION_ERROR);
	174	goto err;
	175	}
	176	}
	177	ctx->exchprovctx = exchange->newctx(ossl_provider_ctx(exchange->prov));
	178	if (ctx->exchprovctx == NULL) {
	179	OPENSSL_secure_clear_free(param, paramsz);
	180	EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX, EVP_R_INITIALIZATION_ERROR);
	181	goto err;
	182	}
	183	ret = exchange->init(ctx->exchprovctx, param);
	184	/*
	185	* TODO(3.0): Really we should detect whether to call OPENSSL_free or
	186	* OPENSSL_secure_clear_free based on the presence of a private key or not.
	187	* Since we always expect a private key to be present we just call
	188	* OPENSSL_secure_clear_free for now.
	189	*/
	190	OPENSSL_secure_clear_free(param, paramsz);
	191
	192	return ret ? 1 : 0;
	193	err:
	194	ctx->operation = EVP_PKEY_OP_UNDEFINED;
	195	return 0;
	196
	197	legacy:
	198	if (ctx == NULL \|\| ctx->pmeth == NULL \|\| ctx->pmeth->derive == NULL) {
	199	EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX,
	200	EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
	201	return -2;
	202	}
	203
	204	if (ctx->pmeth->derive_init == NULL)
	205	return 1;
	206	ret = ctx->pmeth->derive_init(ctx);
	207	if (ret <= 0)
	208	ctx->operation = EVP_PKEY_OP_UNDEFINED;
	209	return ret;
	210	}
	211
	212	int EVP_PKEY_derive_init(EVP_PKEY_CTX *ctx)
	213	{
	214	return EVP_PKEY_derive_init_ex(ctx, NULL);
	215	}
216
217	int EVP_PKEY_derive_set_peer(EVP_PKEY_CTX ctx, EVP_PKEY peer)
218	{
219	int ret;
220	OSSL_PARAM *param = NULL;
221
222	if (ctx == NULL) {
223	EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER,
224	EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
225	return -2;
226	}
227
228	if (ctx->exchprovctx == NULL)
229	goto legacy;
230
231	if (ctx->operation != EVP_PKEY_OP_DERIVE) {
232	EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER,
233	EVP_R_OPERATON_NOT_INITIALIZED);
234	return -1;
235	}
236
237	if (ctx->exchange->set_peer == NULL) {
238	EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER,
239	EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
240	return -2;
241	}
242
243	param = evp_pkey_to_param(peer, NULL);
244	if (param == NULL) {
245	EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER, ERR_R_INTERNAL_ERROR);
246	return 0;
247	}
248	ret = ctx->exchange->set_peer(ctx->exchprovctx, param);
249	/*
250	* TODO(3.0): Really we should detect whether to call OPENSSL_free or
251	* OPENSSL_secure_clear_free based on the presence of a private key or not.
252	* Since we always expect a public key to be present we just call
253	* OPENSSL_free for now.
254	*/
255	OPENSSL_free(param);
256
257	return ret;
258
259	legacy:
260	if (ctx->pmeth == NULL
261	\|\| !(ctx->pmeth->derive != NULL
262	\|\| ctx->pmeth->encrypt != NULL
263	\|\| ctx->pmeth->decrypt != NULL)
264	\|\| ctx->pmeth->ctrl == NULL) {
265	EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER,
266	EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
267	return -2;
268	}
269	if (ctx->operation != EVP_PKEY_OP_DERIVE
270	&& ctx->operation != EVP_PKEY_OP_ENCRYPT
271	&& ctx->operation != EVP_PKEY_OP_DECRYPT) {
272	EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER,
273	EVP_R_OPERATON_NOT_INITIALIZED);
274	return -1;
275	}
276
277	ret = ctx->pmeth->ctrl(ctx, EVP_PKEY_CTRL_PEER_KEY, 0, peer);
278
279	if (ret <= 0)
280	return ret;
281
282	if (ret == 2)
283	return 1;
284
285	if (ctx->pkey == NULL) {
286	EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER, EVP_R_NO_KEY_SET);
287	return -1;
288	}
289
290	if (ctx->pkey->type != peer->type) {
291	EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER, EVP_R_DIFFERENT_KEY_TYPES);
292	return -1;
293	}
294
295	/*
296	* For clarity. The error is if parameters in peer are
297	* present (!missing) but don't match. EVP_PKEY_cmp_parameters may return
298	* 1 (match), 0 (don't match) and -2 (comparison is not defined). -1
299	* (different key types) is impossible here because it is checked earlier.
300	* -2 is OK for us here, as well as 1, so we can check for 0 only.
301	*/
302	if (!EVP_PKEY_missing_parameters(peer) &&
303	!EVP_PKEY_cmp_parameters(ctx->pkey, peer)) {
304	EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER, EVP_R_DIFFERENT_PARAMETERS);
305	return -1;
306	}
307
308	EVP_PKEY_free(ctx->peerkey);
309	ctx->peerkey = peer;
310
311	ret = ctx->pmeth->ctrl(ctx, EVP_PKEY_CTRL_PEER_KEY, 1, peer);
312
313	if (ret <= 0) {
314	ctx->peerkey = NULL;
315	return ret;
316	}
317
318	EVP_PKEY_up_ref(peer);
319	return 1;
320	}
321
322	int EVP_PKEY_derive(EVP_PKEY_CTX ctx, unsigned char key, size_t *pkeylen)
323	{
324	int ret;
325
326	if (ctx == NULL) {
327	EVPerr(EVP_F_EVP_PKEY_DERIVE,
328	EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
329	return -2;
330	}
331
332	if (ctx->operation != EVP_PKEY_OP_DERIVE) {
333	EVPerr(EVP_F_EVP_PKEY_DERIVE, EVP_R_OPERATON_NOT_INITIALIZED);
334	return -1;
335	}
336
337	if (ctx->exchprovctx == NULL)
338	goto legacy;
339
340	ret = ctx->exchange->derive(ctx->exchprovctx, key, pkeylen, SIZE_MAX);
341
342	return ret;
343	legacy:
344	if (ctx == NULL \|\| ctx->pmeth == NULL \|\| ctx->pmeth->derive == NULL) {
345	EVPerr(EVP_F_EVP_PKEY_DERIVE,
346	EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
347	return -2;
348	}
349
350	M_check_autoarg(ctx, key, pkeylen, EVP_F_EVP_PKEY_DERIVE)
351	return ctx->pmeth->derive(ctx, key, pkeylen);
352	}