crypto/evp/exchange.c - third_party/openssl - Git at Google

 /*
  * 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 "internal/numbers.h"   /* includes SIZE_MAX */
 #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 char *name,
                                        const OSSL_DISPATCH *fns,
                                        OSSL_PROVIDER *prov,
                                        void *vkeymgmt_data)
 {
     /*
      * Key exchange cannot work without a key, and key management
      * from the same provider to manage its keys.  We therefore fetch
      * a key management method using the same algorithm and properties
      * and pass that down to evp_generic_fetch to be passed on to our
      * evp_keyexch_from_dispatch, which will attach the key management
      * method to the newly created key exchange method as long as the
      * provider matches.
      */
     struct keymgmt_data_st *keymgmt_data = vkeymgmt_data;
     EVP_KEYMGMT *keymgmt = EVP_KEYMGMT_fetch(keymgmt_data->ctx, name,
                                              keymgmt_data->properties);
     EVP_KEYEXCH *exchange = NULL;
     int fncnt = 0, paramfncnt = 0;

     if (keymgmt == NULL || EVP_KEYMGMT_provider(keymgmt) != prov) {
         ERR_raise(ERR_LIB_EVP, EVP_R_NO_KEYMGMT_AVAILABLE);
         goto err;
     }

     if ((exchange = evp_keyexch_new(prov)) == NULL
         || (exchange->name = OPENSSL_strdup(name)) == NULL) {
         ERR_raise(ERR_LIB_EVP, ERR_R_MALLOC_FAILURE);
         goto err;
     }

     exchange->keymgmt = keymgmt;
     keymgmt = NULL;              /* avoid double free on failure below */

     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;
         case OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS:
             if (exchange->set_ctx_params != NULL)
                 break;
             exchange->set_ctx_params = OSSL_get_OP_keyexch_set_ctx_params(fns);
             paramfncnt++;
             break;
         case OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS:
             if (exchange->settable_ctx_params != NULL)
                 break;
             exchange->settable_ctx_params
                 = OSSL_get_OP_keyexch_settable_ctx_params(fns);
             paramfncnt++;
             break;
         }
     }
     if (fncnt != 4 || (paramfncnt != 0 && paramfncnt != 2)) {
         /*
          * 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 set_ctx_params and settable_ctx_params functions are
          * optional, but if one of them is present then the other one must also
          * be present. The dupctx and set_peer functions are optional.
          */
         EVPerr(EVP_F_EVP_KEYEXCH_FROM_DISPATCH,
                EVP_R_INVALID_PROVIDER_FUNCTIONS);
         goto err;
     }

     return exchange;

  err:
     EVP_KEYEXCH_free(exchange);
     EVP_KEYMGMT_free(keymgmt);
     return NULL;
 }

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

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

 OSSL_PROVIDER *EVP_KEYEXCH_provider(const EVP_KEYEXCH *exchange)
 {
     return exchange->prov;
 }

 EVP_KEYEXCH *EVP_KEYEXCH_fetch(OPENSSL_CTX *ctx, const char *algorithm,
                                const char *properties)
 {
     EVP_KEYEXCH *keyexch = NULL;
     struct keymgmt_data_st keymgmt_data;

     keymgmt_data.ctx = ctx;
     keymgmt_data.properties = properties;
     keyexch = evp_generic_fetch(ctx, OSSL_OP_KEYEXCH, algorithm, properties,
                                 evp_keyexch_from_dispatch, &keymgmt_data,
                                 (int (*)(void *))EVP_KEYEXCH_up_ref,
                                 (void (*)(void *))EVP_KEYEXCH_free);

     return keyexch;
 }

 int EVP_PKEY_derive_init_ex(EVP_PKEY_CTX *ctx, EVP_KEYEXCH *exchange)
 {
     int ret;
     void *provkey = NULL;

     evp_pkey_ctx_free_old_ops(ctx);
     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;
         }
     }

     ctx->op.kex.exchange = exchange;
     if (ctx->pkey != NULL) {
         provkey = evp_keymgmt_export_to_provider(ctx->pkey, exchange->keymgmt);
         if (provkey == NULL) {
             EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX, EVP_R_INITIALIZATION_ERROR);
             goto err;
         }
     }
     ctx->op.kex.exchprovctx = exchange->newctx(ossl_provider_ctx(exchange->prov));
     if (ctx->op.kex.exchprovctx == NULL) {
         /* The provider key can stay in the cache */
         EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX, EVP_R_INITIALIZATION_ERROR);
         goto err;
     }
     ret = exchange->init(ctx->op.kex.exchprovctx, provkey);

     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;
     void *provkey = NULL;

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

     if (!EVP_PKEY_CTX_IS_DERIVE_OP(ctx) || ctx->op.kex.exchprovctx == NULL)
         goto legacy;

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

     provkey = evp_keymgmt_export_to_provider(peer,
                                              ctx->op.kex.exchange->keymgmt);
     if (provkey == NULL) {
         EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER, ERR_R_INTERNAL_ERROR);
         return 0;
     }
     return ctx->op.kex.exchange->set_peer(ctx->op.kex.exchprovctx, provkey);

  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 (!EVP_PKEY_CTX_IS_DERIVE_OP(ctx)) {
         EVPerr(EVP_F_EVP_PKEY_DERIVE, EVP_R_OPERATON_NOT_INITIALIZED);
         return -1;
     }

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

     ret = ctx->op.kex.exchange->derive(ctx->op.kex.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);
 }
	/*
	* 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 "internal/numbers.h" /* includes SIZE_MAX */
	#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 char name,
	const OSSL_DISPATCH *fns,
	OSSL_PROVIDER *prov,
	void *vkeymgmt_data)
	{
	/*
	* Key exchange cannot work without a key, and key management
	* from the same provider to manage its keys. We therefore fetch
	* a key management method using the same algorithm and properties
	* and pass that down to evp_generic_fetch to be passed on to our
	* evp_keyexch_from_dispatch, which will attach the key management
	* method to the newly created key exchange method as long as the
	* provider matches.
	*/
	struct keymgmt_data_st *keymgmt_data = vkeymgmt_data;
	EVP_KEYMGMT *keymgmt = EVP_KEYMGMT_fetch(keymgmt_data->ctx, name,
	keymgmt_data->properties);
	EVP_KEYEXCH *exchange = NULL;
	int fncnt = 0, paramfncnt = 0;

	if (keymgmt == NULL \|\| EVP_KEYMGMT_provider(keymgmt) != prov) {
	ERR_raise(ERR_LIB_EVP, EVP_R_NO_KEYMGMT_AVAILABLE);
	goto err;
	}

	if ((exchange = evp_keyexch_new(prov)) == NULL
	\|\| (exchange->name = OPENSSL_strdup(name)) == NULL) {
	ERR_raise(ERR_LIB_EVP, ERR_R_MALLOC_FAILURE);
	goto err;
	}

	exchange->keymgmt = keymgmt;
	keymgmt = NULL; /* avoid double free on failure below */

	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;
	case OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS:
	if (exchange->set_ctx_params != NULL)
	break;
	exchange->set_ctx_params = OSSL_get_OP_keyexch_set_ctx_params(fns);
	paramfncnt++;
	break;
	case OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS:
	if (exchange->settable_ctx_params != NULL)
	break;
	exchange->settable_ctx_params
	= OSSL_get_OP_keyexch_settable_ctx_params(fns);
	paramfncnt++;
	break;
	}
	}
	if (fncnt != 4 \|\| (paramfncnt != 0 && paramfncnt != 2)) {
	/*
	* 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 set_ctx_params and settable_ctx_params functions are
	* optional, but if one of them is present then the other one must also
	* be present. The dupctx and set_peer functions are optional.
	*/
	EVPerr(EVP_F_EVP_KEYEXCH_FROM_DISPATCH,
	EVP_R_INVALID_PROVIDER_FUNCTIONS);
	goto err;
	}

	return exchange;

	err:
	EVP_KEYEXCH_free(exchange);
	EVP_KEYMGMT_free(keymgmt);
	return NULL;
	}

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

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

	OSSL_PROVIDER EVP_KEYEXCH_provider(const EVP_KEYEXCH exchange)
	{
	return exchange->prov;
	}

	EVP_KEYEXCH EVP_KEYEXCH_fetch(OPENSSL_CTX ctx, const char *algorithm,
	const char *properties)
	{
	EVP_KEYEXCH *keyexch = NULL;
	struct keymgmt_data_st keymgmt_data;

	keymgmt_data.ctx = ctx;
	keymgmt_data.properties = properties;
	keyexch = evp_generic_fetch(ctx, OSSL_OP_KEYEXCH, algorithm, properties,
	evp_keyexch_from_dispatch, &keymgmt_data,
	(int ()(void ))EVP_KEYEXCH_up_ref,
	(void ()(void ))EVP_KEYEXCH_free);

	return keyexch;
	}

	int EVP_PKEY_derive_init_ex(EVP_PKEY_CTX ctx, EVP_KEYEXCH exchange)
	{
	int ret;
	void *provkey = NULL;

	evp_pkey_ctx_free_old_ops(ctx);
	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;
	}
	}

	ctx->op.kex.exchange = exchange;
	if (ctx->pkey != NULL) {
	provkey = evp_keymgmt_export_to_provider(ctx->pkey, exchange->keymgmt);
	if (provkey == NULL) {
	EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX, EVP_R_INITIALIZATION_ERROR);
	goto err;
	}
	}
	ctx->op.kex.exchprovctx = exchange->newctx(ossl_provider_ctx(exchange->prov));
	if (ctx->op.kex.exchprovctx == NULL) {
	/* The provider key can stay in the cache */
	EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX, EVP_R_INITIALIZATION_ERROR);
	goto err;
	}
	ret = exchange->init(ctx->op.kex.exchprovctx, provkey);

	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;
	void *provkey = NULL;

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

	if (!EVP_PKEY_CTX_IS_DERIVE_OP(ctx) \|\| ctx->op.kex.exchprovctx == NULL)
	goto legacy;

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

	provkey = evp_keymgmt_export_to_provider(peer,
	ctx->op.kex.exchange->keymgmt);
	if (provkey == NULL) {
	EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER, ERR_R_INTERNAL_ERROR);
	return 0;
	}
	return ctx->op.kex.exchange->set_peer(ctx->op.kex.exchprovctx, provkey);

	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 (!EVP_PKEY_CTX_IS_DERIVE_OP(ctx)) {
	EVPerr(EVP_F_EVP_PKEY_DERIVE, EVP_R_OPERATON_NOT_INITIALIZED);
	return -1;
	}

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

	ret = ctx->op.kex.exchange->derive(ctx->op.kex.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);
	}