2 * Copyright 2020 The OpenSSL Project Authors. All Rights Reserved.
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
11 * ECDH low level APIs are deprecated for public use, but still ok for
14 #include "internal/deprecated.h"
17 #include <openssl/crypto.h>
18 #include <openssl/evp.h>
19 #include <openssl/core_dispatch.h>
20 #include <openssl/core_names.h>
21 #include <openssl/ec.h>
22 #include <openssl/params.h>
23 #include <openssl/err.h>
24 #include "prov/provider_ctx.h"
25 #include "prov/providercommon.h"
26 #include "prov/implementations.h"
27 #include "prov/securitycheck.h"
28 #include "crypto/ec.h" /* ecdh_KDF_X9_63() */
30 static OSSL_FUNC_keyexch_newctx_fn ecdh_newctx;
31 static OSSL_FUNC_keyexch_init_fn ecdh_init;
32 static OSSL_FUNC_keyexch_set_peer_fn ecdh_set_peer;
33 static OSSL_FUNC_keyexch_derive_fn ecdh_derive;
34 static OSSL_FUNC_keyexch_freectx_fn ecdh_freectx;
35 static OSSL_FUNC_keyexch_dupctx_fn ecdh_dupctx;
36 static OSSL_FUNC_keyexch_set_ctx_params_fn ecdh_set_ctx_params;
37 static OSSL_FUNC_keyexch_settable_ctx_params_fn ecdh_settable_ctx_params;
38 static OSSL_FUNC_keyexch_get_ctx_params_fn ecdh_get_ctx_params;
39 static OSSL_FUNC_keyexch_gettable_ctx_params_fn ecdh_gettable_ctx_params;
42 PROV_ECDH_KDF_NONE = 0,
47 * What's passed as an actual key is defined by the KEYMGMT interface.
48 * We happen to know that our KEYMGMT simply passes EC_KEY structures, so
49 * we use that here too.
63 * . -1 use cofactor mode set for k
70 /* KDF (if any) to use for ECDH */
71 enum kdf_type kdf_type;
72 /* Message digest to use for key derivation */
74 /* User key material */
75 unsigned char *kdf_ukm;
77 /* KDF output length */
82 void *ecdh_newctx(void *provctx)
86 if (!ossl_prov_is_running())
89 pectx = OPENSSL_zalloc(sizeof(*pectx));
93 pectx->libctx = PROV_LIBRARY_CONTEXT_OF(provctx);
94 pectx->cofactor_mode = -1;
95 pectx->kdf_type = PROV_ECDH_KDF_NONE;
101 int ecdh_init(void *vpecdhctx, void *vecdh)
103 PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;
105 if (!ossl_prov_is_running()
108 || !EC_KEY_up_ref(vecdh))
110 EC_KEY_free(pecdhctx->k);
112 pecdhctx->cofactor_mode = -1;
113 pecdhctx->kdf_type = PROV_ECDH_KDF_NONE;
114 return ec_check_key(vecdh, 1);
118 int ecdh_set_peer(void *vpecdhctx, void *vecdh)
120 PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;
122 if (!ossl_prov_is_running()
125 || !EC_KEY_up_ref(vecdh))
127 EC_KEY_free(pecdhctx->peerk);
128 pecdhctx->peerk = vecdh;
129 return ec_check_key(vecdh, 1);
133 void ecdh_freectx(void *vpecdhctx)
135 PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;
137 EC_KEY_free(pecdhctx->k);
138 EC_KEY_free(pecdhctx->peerk);
140 EVP_MD_free(pecdhctx->kdf_md);
141 OPENSSL_clear_free(pecdhctx->kdf_ukm, pecdhctx->kdf_ukmlen);
143 OPENSSL_free(pecdhctx);
147 void *ecdh_dupctx(void *vpecdhctx)
149 PROV_ECDH_CTX *srcctx = (PROV_ECDH_CTX *)vpecdhctx;
150 PROV_ECDH_CTX *dstctx;
152 if (!ossl_prov_is_running())
155 dstctx = OPENSSL_zalloc(sizeof(*srcctx));
161 /* clear all pointers */
164 dstctx->peerk = NULL;
165 dstctx->kdf_md = NULL;
166 dstctx->kdf_ukm = NULL;
168 /* up-ref all ref-counted objects referenced in dstctx */
170 if (srcctx->k != NULL && !EC_KEY_up_ref(srcctx->k))
173 dstctx->k = srcctx->k;
175 if (srcctx->peerk != NULL && !EC_KEY_up_ref(srcctx->peerk))
178 dstctx->peerk = srcctx->peerk;
180 if (srcctx->kdf_md != NULL && !EVP_MD_up_ref(srcctx->kdf_md))
183 dstctx->kdf_md = srcctx->kdf_md;
185 /* Duplicate UKM data if present */
186 if (srcctx->kdf_ukm != NULL && srcctx->kdf_ukmlen > 0) {
187 dstctx->kdf_ukm = OPENSSL_memdup(srcctx->kdf_ukm,
189 if (dstctx->kdf_ukm == NULL)
196 ecdh_freectx(dstctx);
201 int ecdh_set_ctx_params(void *vpecdhctx, const OSSL_PARAM params[])
203 char name[80] = { '\0' }; /* should be big enough */
205 PROV_ECDH_CTX *pectx = (PROV_ECDH_CTX *)vpecdhctx;
208 if (pectx == NULL || params == NULL)
211 p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE);
215 if (!OSSL_PARAM_get_int(p, &mode))
218 if (mode < -1 || mode > 1)
221 pectx->cofactor_mode = mode;
224 p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
227 if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
231 pectx->kdf_type = PROV_ECDH_KDF_NONE;
232 else if (strcmp(name, OSSL_KDF_NAME_X963KDF) == 0)
233 pectx->kdf_type = PROV_ECDH_KDF_X9_63;
238 p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
240 char mdprops[80] = { '\0' }; /* should be big enough */
243 if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
247 p = OSSL_PARAM_locate_const(params,
248 OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS);
251 if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(mdprops)))
255 EVP_MD_free(pectx->kdf_md);
256 pectx->kdf_md = EVP_MD_fetch(pectx->libctx, name, mdprops);
257 if (!digest_is_allowed(pectx->kdf_md)) {
258 EVP_MD_free(pectx->kdf_md);
259 pectx->kdf_md = NULL;
261 if (pectx->kdf_md == NULL)
265 p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
269 if (!OSSL_PARAM_get_size_t(p, &outlen))
271 pectx->kdf_outlen = outlen;
274 p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
276 void *tmp_ukm = NULL;
279 if (!OSSL_PARAM_get_octet_string(p, &tmp_ukm, 0, &tmp_ukmlen))
281 OPENSSL_free(pectx->kdf_ukm);
282 pectx->kdf_ukm = tmp_ukm;
283 pectx->kdf_ukmlen = tmp_ukmlen;
289 static const OSSL_PARAM known_settable_ctx_params[] = {
290 OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE, NULL),
291 OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
292 OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
293 OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS, NULL, 0),
294 OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
295 OSSL_PARAM_octet_string(OSSL_EXCHANGE_PARAM_KDF_UKM, NULL, 0),
300 const OSSL_PARAM *ecdh_settable_ctx_params(ossl_unused void *provctx)
302 return known_settable_ctx_params;
306 int ecdh_get_ctx_params(void *vpecdhctx, OSSL_PARAM params[])
308 PROV_ECDH_CTX *pectx = (PROV_ECDH_CTX *)vpecdhctx;
311 if (pectx == NULL || params == NULL)
314 p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE);
316 int mode = pectx->cofactor_mode;
319 /* check what is the default for pecdhctx->k */
320 mode = EC_KEY_get_flags(pectx->k) & EC_FLAG_COFACTOR_ECDH ? 1 : 0;
323 if (!OSSL_PARAM_set_int(p, mode))
327 p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
329 const char *kdf_type = NULL;
331 switch (pectx->kdf_type) {
332 case PROV_ECDH_KDF_NONE:
335 case PROV_ECDH_KDF_X9_63:
336 kdf_type = OSSL_KDF_NAME_X963KDF;
342 if (!OSSL_PARAM_set_utf8_string(p, kdf_type))
346 p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
348 && !OSSL_PARAM_set_utf8_string(p, pectx->kdf_md == NULL
350 : EVP_MD_name(pectx->kdf_md))){
354 p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
355 if (p != NULL && !OSSL_PARAM_set_size_t(p, pectx->kdf_outlen))
358 p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
359 if (p != NULL && !OSSL_PARAM_set_octet_ptr(p, pectx->kdf_ukm, 0))
362 p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_UKM_LEN);
363 if (p != NULL && !OSSL_PARAM_set_size_t(p, pectx->kdf_ukmlen))
369 static const OSSL_PARAM known_gettable_ctx_params[] = {
370 OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE, NULL),
371 OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
372 OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
373 OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
374 OSSL_PARAM_DEFN(OSSL_EXCHANGE_PARAM_KDF_UKM, OSSL_PARAM_OCTET_PTR,
376 OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_UKM_LEN, NULL),
381 const OSSL_PARAM *ecdh_gettable_ctx_params(ossl_unused void *provctx)
383 return known_gettable_ctx_params;
387 size_t ecdh_size(const EC_KEY *k)
390 const EC_GROUP *group;
393 || (group = EC_KEY_get0_group(k)) == NULL)
396 degree = EC_GROUP_get_degree(group);
398 return (degree + 7) / 8;
402 int ecdh_plain_derive(void *vpecdhctx, unsigned char *secret,
403 size_t *psecretlen, size_t outlen)
405 PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;
407 size_t ecdhsize, size;
408 const EC_POINT *ppubkey = NULL;
409 EC_KEY *privk = NULL;
410 const EC_GROUP *group;
411 const BIGNUM *cofactor;
412 int key_cofactor_mode;
414 if (pecdhctx->k == NULL || pecdhctx->peerk == NULL) {
415 ERR_raise(ERR_LIB_PROV, EC_R_KEYS_NOT_SET);
419 ecdhsize = ecdh_size(pecdhctx->k);
420 if (secret == NULL) {
421 *psecretlen = ecdhsize;
425 if ((group = EC_KEY_get0_group(pecdhctx->k)) == NULL
426 || (cofactor = EC_GROUP_get0_cofactor(group)) == NULL )
430 * NB: unlike PKCS#3 DH, if outlen is less than maximum size this is not
431 * an error, the result is truncated.
433 size = outlen < ecdhsize ? outlen : ecdhsize;
436 * The ctx->cofactor_mode flag has precedence over the
437 * cofactor_mode flag set on ctx->k.
439 * - if ctx->cofactor_mode == -1, use ctx->k directly
440 * - if ctx->cofactor_mode == key_cofactor_mode, use ctx->k directly
441 * - if ctx->cofactor_mode != key_cofactor_mode:
442 * - if ctx->k->cofactor == 1, the cofactor_mode flag is irrelevant, use
444 * - if ctx->k->cofactor != 1, use a duplicate of ctx->k with the flag
445 * set to ctx->cofactor_mode
448 (EC_KEY_get_flags(pecdhctx->k) & EC_FLAG_COFACTOR_ECDH) ? 1 : 0;
449 if (pecdhctx->cofactor_mode != -1
450 && pecdhctx->cofactor_mode != key_cofactor_mode
451 && !BN_is_one(cofactor)) {
452 if ((privk = EC_KEY_dup(pecdhctx->k)) == NULL)
455 if (pecdhctx->cofactor_mode == 1)
456 EC_KEY_set_flags(privk, EC_FLAG_COFACTOR_ECDH);
458 EC_KEY_clear_flags(privk, EC_FLAG_COFACTOR_ECDH);
463 ppubkey = EC_KEY_get0_public_key(pecdhctx->peerk);
465 retlen = ECDH_compute_key(secret, size, ppubkey, privk, NULL);
470 *psecretlen = retlen;
474 if (privk != pecdhctx->k)
480 int ecdh_X9_63_kdf_derive(void *vpecdhctx, unsigned char *secret,
481 size_t *psecretlen, size_t outlen)
483 PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;
484 unsigned char *stmp = NULL;
488 if (secret == NULL) {
489 *psecretlen = pecdhctx->kdf_outlen;
493 if (pecdhctx->kdf_outlen > outlen)
495 if (!ecdh_plain_derive(vpecdhctx, NULL, &stmplen, 0))
497 if ((stmp = OPENSSL_secure_malloc(stmplen)) == NULL) {
498 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
501 if (!ecdh_plain_derive(vpecdhctx, stmp, &stmplen, stmplen))
505 if (!ecdh_KDF_X9_63(secret, pecdhctx->kdf_outlen,
508 pecdhctx->kdf_ukmlen,
510 pecdhctx->libctx, NULL))
512 *psecretlen = pecdhctx->kdf_outlen;
516 OPENSSL_secure_clear_free(stmp, stmplen);
521 int ecdh_derive(void *vpecdhctx, unsigned char *secret,
522 size_t *psecretlen, size_t outlen)
524 PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;
526 switch (pecdhctx->kdf_type) {
527 case PROV_ECDH_KDF_NONE:
528 return ecdh_plain_derive(vpecdhctx, secret, psecretlen, outlen);
529 case PROV_ECDH_KDF_X9_63:
530 return ecdh_X9_63_kdf_derive(vpecdhctx, secret, psecretlen, outlen);
537 const OSSL_DISPATCH ecossl_dh_keyexch_functions[] = {
538 { OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))ecdh_newctx },
539 { OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))ecdh_init },
540 { OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))ecdh_derive },
541 { OSSL_FUNC_KEYEXCH_SET_PEER, (void (*)(void))ecdh_set_peer },
542 { OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))ecdh_freectx },
543 { OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))ecdh_dupctx },
544 { OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS, (void (*)(void))ecdh_set_ctx_params },
545 { OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS,
546 (void (*)(void))ecdh_settable_ctx_params },
547 { OSSL_FUNC_KEYEXCH_GET_CTX_PARAMS, (void (*)(void))ecdh_get_ctx_params },
548 { OSSL_FUNC_KEYEXCH_GETTABLE_CTX_PARAMS,
549 (void (*)(void))ecdh_gettable_ctx_params },