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/ECDSA low level APIs are deprecated for public use, but still ok for
14 #include "internal/deprecated.h"
16 #include <openssl/core_numbers.h>
17 #include <openssl/core_names.h>
18 #include <openssl/bn.h>
19 #include <openssl/objects.h>
20 #include <openssl/params.h>
21 #include "crypto/bn.h"
22 #include "crypto/ec.h"
23 #include "internal/param_build.h"
24 #include "prov/implementations.h"
25 #include "prov/providercommon.h"
26 #include "prov/provider_ctx.h"
28 static OSSL_OP_keymgmt_new_fn ec_newdata;
29 static OSSL_OP_keymgmt_free_fn ec_freedata;
30 static OSSL_OP_keymgmt_get_params_fn ec_get_params;
31 static OSSL_OP_keymgmt_gettable_params_fn ec_gettable_params;
32 static OSSL_OP_keymgmt_set_params_fn ec_set_params;
33 static OSSL_OP_keymgmt_settable_params_fn ec_settable_params;
34 static OSSL_OP_keymgmt_has_fn ec_has;
35 static OSSL_OP_keymgmt_match_fn ec_match;
36 static OSSL_OP_keymgmt_validate_fn ec_validate;
37 static OSSL_OP_keymgmt_import_fn ec_import;
38 static OSSL_OP_keymgmt_import_types_fn ec_import_types;
39 static OSSL_OP_keymgmt_export_fn ec_export;
40 static OSSL_OP_keymgmt_export_types_fn ec_export_types;
41 static OSSL_OP_keymgmt_query_operation_name_fn ec_query_operation_name;
43 #define EC_POSSIBLE_SELECTIONS \
44 (OSSL_KEYMGMT_SELECT_KEYPAIR | OSSL_KEYMGMT_SELECT_ALL_PARAMETERS )
47 const char *ec_query_operation_name(int operation_id)
49 switch (operation_id) {
52 case OSSL_OP_SIGNATURE:
59 int params_to_domparams(EC_KEY *ec, const OSSL_PARAM params[])
61 const OSSL_PARAM *param_ec_name;
63 char *curve_name = NULL;
69 param_ec_name = OSSL_PARAM_locate_const(params, OSSL_PKEY_PARAM_EC_NAME);
70 if (param_ec_name == NULL) {
71 /* explicit parameters */
74 * TODO(3.0): should we support explicit parameters curves?
81 if (!OSSL_PARAM_get_utf8_string(param_ec_name, &curve_name, 0)
83 || (curve_nid = ec_curve_name2nid(curve_name)) == NID_undef)
86 if ((ecg = EC_GROUP_new_by_curve_name_ex(ec_key_get_libctx(ec),
91 if (!EC_KEY_set_group(ec, ecg))
95 * TODO(3.0): if the group has changed, should we invalidate the private and
102 OPENSSL_free(curve_name);
108 int domparams_to_params(const EC_KEY *ec, OSSL_PARAM_BLD *tmpl)
116 ecg = EC_KEY_get0_group(ec);
120 curve_nid = EC_GROUP_get_curve_name(ecg);
122 if (curve_nid == NID_undef) {
123 /* explicit parameters */
126 * TODO(3.0): should we support explicit parameters curves?
131 const char *curve_name = NULL;
133 if ((curve_name = ec_curve_nid2name(curve_nid)) == NULL)
136 if (!ossl_param_bld_push_utf8_string(tmpl, OSSL_PKEY_PARAM_EC_NAME,
145 * Callers of params_to_key MUST make sure that params_to_domparams has been
148 * This function only imports the bare keypair, domain parameters and other
149 * parameters are imported separately, and domain parameters are required to
153 int params_to_key(EC_KEY *ec, const OSSL_PARAM params[], int include_private)
155 const OSSL_PARAM *param_priv_key, *param_pub_key;
157 BIGNUM *priv_key = NULL;
158 unsigned char *pub_key = NULL;
160 const EC_GROUP *ecg = NULL;
161 EC_POINT *pub_point = NULL;
164 ecg = EC_KEY_get0_group(ec);
169 OSSL_PARAM_locate_const(params, OSSL_PKEY_PARAM_PRIV_KEY);
171 OSSL_PARAM_locate_const(params, OSSL_PKEY_PARAM_PUB_KEY);
173 ctx = BN_CTX_new_ex(ec_key_get_libctx(ec));
177 * We want to have at least a public key either way, so we end up
178 * requiring it unconditionally.
180 if (param_pub_key == NULL
181 || !OSSL_PARAM_get_octet_string(param_pub_key,
182 (void **)&pub_key, 0, &pub_key_len)
183 || (pub_point = EC_POINT_new(ecg)) == NULL
184 || !EC_POINT_oct2point(ecg, pub_point,
185 pub_key, pub_key_len, ctx))
188 if (param_priv_key != NULL && include_private) {
193 * Key import/export should never leak the bit length of the secret
196 * For this reason, on export we use padded BIGNUMs with fixed length.
198 * When importing we also should make sure that, even if short lived,
199 * the newly created BIGNUM is marked with the BN_FLG_CONSTTIME flag as
200 * soon as possible, so that any processing of this BIGNUM might opt for
201 * constant time implementations in the backend.
203 * Setting the BN_FLG_CONSTTIME flag alone is never enough, we also have
204 * to preallocate the BIGNUM internal buffer to a fixed public size big
205 * enough that operations performed during the processing never trigger
206 * a realloc which would leak the size of the scalar through memory
212 * The order of the large prime subgroup of the curve is our choice for
213 * a fixed public size, as that is generally the upper bound for
214 * generating a private key in EC cryptosystems and should fit all valid
217 * For padding on export we just use the bit length of the order
218 * converted to bytes (rounding up).
220 * For preallocating the BIGNUM storage we look at the number of "words"
221 * required for the internal representation of the order, and we
222 * preallocate 2 extra "words" in case any of the subsequent processing
223 * might temporarily overflow the order length.
225 order = EC_GROUP_get0_order(ecg);
226 if (order == NULL || BN_is_zero(order))
229 fixed_top = bn_get_top(order) + 2;
231 if ((priv_key = BN_secure_new()) == NULL)
233 if (bn_wexpand(priv_key, fixed_top) == NULL)
235 BN_set_flags(priv_key, BN_FLG_CONSTTIME);
237 if (!OSSL_PARAM_get_BN(param_priv_key, &priv_key))
242 && !EC_KEY_set_private_key(ec, priv_key))
245 if (!EC_KEY_set_public_key(ec, pub_point))
252 BN_clear_free(priv_key);
253 OPENSSL_free(pub_key);
254 EC_POINT_free(pub_point);
259 * Callers of key_to_params MUST make sure that domparams_to_params is also
262 * This function only exports the bare keypair, domain parameters and other
263 * parameters are exported separately.
266 int key_to_params(const EC_KEY *eckey, OSSL_PARAM_BLD *tmpl, int include_private)
268 const BIGNUM *priv_key = NULL;
269 const EC_POINT *pub_point = NULL;
270 const EC_GROUP *ecg = NULL;
271 unsigned char *pub_key = NULL;
272 size_t pub_key_len = 0;
278 ecg = EC_KEY_get0_group(eckey);
279 priv_key = EC_KEY_get0_private_key(eckey);
280 pub_point = EC_KEY_get0_public_key(eckey);
282 /* group and public_key must be present, priv_key is optional */
283 if (ecg == NULL || pub_point == NULL)
285 if ((pub_key_len = EC_POINT_point2buf(ecg, pub_point,
286 POINT_CONVERSION_COMPRESSED,
287 &pub_key, NULL)) == 0)
290 if (!ossl_param_bld_push_octet_string(tmpl,
291 OSSL_PKEY_PARAM_PUB_KEY,
292 pub_key, pub_key_len))
295 if (priv_key != NULL && include_private) {
300 * Key import/export should never leak the bit length of the secret
303 * For this reason, on export we use padded BIGNUMs with fixed length.
305 * When importing we also should make sure that, even if short lived,
306 * the newly created BIGNUM is marked with the BN_FLG_CONSTTIME flag as
307 * soon as possible, so that any processing of this BIGNUM might opt for
308 * constant time implementations in the backend.
310 * Setting the BN_FLG_CONSTTIME flag alone is never enough, we also have
311 * to preallocate the BIGNUM internal buffer to a fixed public size big
312 * enough that operations performed during the processing never trigger
313 * a realloc which would leak the size of the scalar through memory
319 * The order of the large prime subgroup of the curve is our choice for
320 * a fixed public size, as that is generally the upper bound for
321 * generating a private key in EC cryptosystems and should fit all valid
324 * For padding on export we just use the bit length of the order
325 * converted to bytes (rounding up).
327 * For preallocating the BIGNUM storage we look at the number of "words"
328 * required for the internal representation of the order, and we
329 * preallocate 2 extra "words" in case any of the subsequent processing
330 * might temporarily overflow the order length.
332 ecbits = EC_GROUP_order_bits(ecg);
335 sz = (ecbits + 7 ) / 8;
336 if (!ossl_param_bld_push_BN_pad(tmpl,
337 OSSL_PKEY_PARAM_PRIV_KEY,
345 OPENSSL_free(pub_key);
350 int ec_set_param_ecdh_cofactor_mode(EC_KEY *ec, const OSSL_PARAM *p)
352 const EC_GROUP *ecg = EC_KEY_get0_group(ec);
353 const BIGNUM *cofactor;
356 if (!OSSL_PARAM_get_int(p, &mode))
360 * mode can be only 0 for disable, or 1 for enable here.
362 * This is in contrast with the same parameter on an ECDH EVP_PKEY_CTX that
363 * also supports mode == -1 with the meaning of "reset to the default for
364 * the associated key".
366 if (mode < 0 || mode > 1)
369 if ((cofactor = EC_GROUP_get0_cofactor(ecg)) == NULL )
372 /* ECDH cofactor mode has no effect if cofactor is 1 */
373 if (BN_is_one(cofactor))
377 EC_KEY_set_flags(ec, EC_FLAG_COFACTOR_ECDH);
379 EC_KEY_clear_flags(ec, EC_FLAG_COFACTOR_ECDH);
385 int params_to_otherparams(EC_KEY *ec, const OSSL_PARAM params[])
392 p = OSSL_PARAM_locate_const(params, OSSL_PKEY_PARAM_USE_COFACTOR_ECDH);
393 if (p != NULL && !ec_set_param_ecdh_cofactor_mode(ec, p))
400 int otherparams_to_params(const EC_KEY *ec, OSSL_PARAM_BLD *tmpl)
402 int ecdh_cofactor_mode = 0;
408 (EC_KEY_get_flags(ec) & EC_FLAG_COFACTOR_ECDH) ? 1 : 0;
409 if (!ossl_param_bld_push_int(tmpl,
410 OSSL_PKEY_PARAM_USE_COFACTOR_ECDH,
418 void *ec_newdata(void *provctx)
420 return EC_KEY_new_ex(PROV_LIBRARY_CONTEXT_OF(provctx));
424 void ec_freedata(void *keydata)
426 EC_KEY_free(keydata);
430 int ec_has(void *keydata, int selection)
432 EC_KEY *ec = keydata;
435 if ((selection & EC_POSSIBLE_SELECTIONS) != 0)
438 if ((selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0)
439 ok = ok && (EC_KEY_get0_public_key(ec) != NULL);
440 if ((selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0)
441 ok = ok && (EC_KEY_get0_private_key(ec) != NULL);
442 if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) != 0)
443 ok = ok && (EC_KEY_get0_group(ec) != NULL);
445 * We consider OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS to always be available,
446 * so no extra check is needed other than the previous one against
447 * EC_POSSIBLE_SELECTIONS.
453 static int ec_match(const void *keydata1, const void *keydata2, int selection)
455 const EC_KEY *ec1 = keydata1;
456 const EC_KEY *ec2 = keydata2;
457 const EC_GROUP *group_a = EC_KEY_get0_group(ec1);
458 const EC_GROUP *group_b = EC_KEY_get0_group(ec2);
461 if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) != 0)
462 ok = ok && group_a != NULL && group_b != NULL
463 && EC_GROUP_cmp(group_a, group_b, NULL) == 0;
464 if ((selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0) {
465 const BIGNUM *pa = EC_KEY_get0_private_key(ec1);
466 const BIGNUM *pb = EC_KEY_get0_private_key(ec2);
468 ok = ok && BN_cmp(pa, pb) == 0;
470 if ((selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0) {
471 const EC_POINT *pa = EC_KEY_get0_public_key(ec1);
472 const EC_POINT *pb = EC_KEY_get0_public_key(ec2);
474 ok = ok && EC_POINT_cmp(group_b, pa, pb, NULL);
480 int ec_import(void *keydata, int selection, const OSSL_PARAM params[])
482 EC_KEY *ec = keydata;
489 * In this implementation, we can export/import only keydata in the
490 * following combinations:
491 * - domain parameters only
492 * - public key with associated domain parameters (+optional other params)
493 * - private key with associated public key and domain parameters
494 * (+optional other params)
497 * - domain parameters must always be requested
498 * - private key must be requested alongside public key
499 * - other parameters must be requested only alongside a key
501 if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) == 0)
503 if ((selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0
504 && (selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) == 0)
506 if ((selection & OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS) != 0
507 && (selection & OSSL_KEYMGMT_SELECT_KEYPAIR) == 0)
510 if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) != 0)
511 ok = ok && params_to_domparams(ec, params);
512 if ((selection & OSSL_KEYMGMT_SELECT_KEYPAIR) != 0) {
513 int include_private =
514 selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY ? 1 : 0;
516 ok = ok && params_to_key(ec, params, include_private);
518 if ((selection & OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS) != 0)
519 ok = ok && params_to_otherparams(ec, params);
525 int ec_export(void *keydata, int selection, OSSL_CALLBACK *param_cb,
528 EC_KEY *ec = keydata;
530 OSSL_PARAM *params = NULL;
537 * In this implementation, we can export/import only keydata in the
538 * following combinations:
539 * - domain parameters only
540 * - public key with associated domain parameters (+optional other params)
541 * - private key with associated public key and domain parameters
542 * (+optional other params)
545 * - domain parameters must always be requested
546 * - private key must be requested alongside public key
547 * - other parameters must be requested only alongside a key
549 if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) == 0)
551 if ((selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0
552 && (selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) == 0)
554 if ((selection & OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS) != 0
555 && (selection & OSSL_KEYMGMT_SELECT_KEYPAIR) == 0)
558 ossl_param_bld_init(&tmpl);
560 if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) != 0)
561 ok = ok && domparams_to_params(ec, &tmpl);
562 if ((selection & OSSL_KEYMGMT_SELECT_KEYPAIR) != 0) {
563 int include_private =
564 selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY ? 1 : 0;
566 ok = ok && key_to_params(ec, &tmpl, include_private);
568 if ((selection & OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS) != 0)
569 ok = ok && otherparams_to_params(ec, &tmpl);
572 || (params = ossl_param_bld_to_param(&tmpl)) == NULL)
575 ok = param_cb(params, cbarg);
576 ossl_param_bld_free(params);
580 /* IMEXPORT = IMPORT + EXPORT */
582 # define EC_IMEXPORTABLE_DOM_PARAMETERS \
583 OSSL_PARAM_utf8_string(OSSL_PKEY_PARAM_EC_NAME, NULL, 0)
584 # define EC_IMEXPORTABLE_PUBLIC_KEY \
585 OSSL_PARAM_octet_string(OSSL_PKEY_PARAM_PUB_KEY, NULL, 0)
586 # define EC_IMEXPORTABLE_PRIVATE_KEY \
587 OSSL_PARAM_BN(OSSL_PKEY_PARAM_PRIV_KEY, NULL, 0)
588 # define EC_IMEXPORTABLE_OTHER_PARAMETERS \
589 OSSL_PARAM_int(OSSL_PKEY_PARAM_USE_COFACTOR_ECDH, NULL)
592 * Include all the possible combinations of OSSL_PARAM arrays for
593 * ec_imexport_types().
595 * They are in a separate file as it is ~100 lines of unreadable and
596 * uninteresting machine generated stuff.
598 * TODO(3.0): the generated list looks quite ugly, as to cover all possible
599 * combinations of the bits in `selection`, it also includes combinations that
600 * are not really useful: we might want to consider alternatives to this
603 #include "ec_kmgmt_imexport.inc"
606 const OSSL_PARAM *ec_imexport_types(int selection)
610 if ((selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0)
612 if ((selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0)
614 if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) != 0)
616 if ((selection & OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS) != 0)
618 return ec_types[type_select];
622 const OSSL_PARAM *ec_import_types(int selection)
624 return ec_imexport_types(selection);
628 const OSSL_PARAM *ec_export_types(int selection)
630 return ec_imexport_types(selection);
634 int ec_get_params(void *key, OSSL_PARAM params[])
637 const EC_GROUP *ecg = NULL;
640 ecg = EC_KEY_get0_group(eck);
644 if ((p = OSSL_PARAM_locate(params, OSSL_PKEY_PARAM_MAX_SIZE)) != NULL
645 && !OSSL_PARAM_set_int(p, ECDSA_size(eck)))
647 if ((p = OSSL_PARAM_locate(params, OSSL_PKEY_PARAM_BITS)) != NULL
648 && !OSSL_PARAM_set_int(p, EC_GROUP_order_bits(ecg)))
650 if ((p = OSSL_PARAM_locate(params, OSSL_PKEY_PARAM_SECURITY_BITS)) != NULL) {
651 int ecbits, sec_bits;
653 ecbits = EC_GROUP_order_bits(ecg);
656 * The following estimates are based on the values published
657 * in Table 2 of "NIST Special Publication 800-57 Part 1 Revision 4"
658 * at http://dx.doi.org/10.6028/NIST.SP.800-57pt1r4 .
660 * Note that the above reference explicitly categorizes algorithms in a
661 * discrete set of values {80, 112, 128, 192, 256}, and that it is
662 * relevant only for NIST approved Elliptic Curves, while OpenSSL
663 * applies the same logic also to other curves.
665 * Classifications produced by other standardazing bodies might differ,
666 * so the results provided for "bits of security" by this provider are
667 * to be considered merely indicative, and it is the users'
668 * responsibility to compare these values against the normative
669 * references that may be relevant for their intent and purposes.
673 else if (ecbits >= 384)
675 else if (ecbits >= 256)
677 else if (ecbits >= 224)
679 else if (ecbits >= 160)
682 sec_bits = ecbits / 2;
684 if (!OSSL_PARAM_set_int(p, sec_bits))
688 p = OSSL_PARAM_locate(params, OSSL_PKEY_PARAM_USE_COFACTOR_ECDH);
690 int ecdh_cofactor_mode = 0;
693 (EC_KEY_get_flags(eck) & EC_FLAG_COFACTOR_ECDH) ? 1 : 0;
695 if (!OSSL_PARAM_set_int(p, ecdh_cofactor_mode))
702 static const OSSL_PARAM ec_known_gettable_params[] = {
703 OSSL_PARAM_int(OSSL_PKEY_PARAM_BITS, NULL),
704 OSSL_PARAM_int(OSSL_PKEY_PARAM_SECURITY_BITS, NULL),
705 OSSL_PARAM_int(OSSL_PKEY_PARAM_MAX_SIZE, NULL),
706 OSSL_PARAM_int(OSSL_PKEY_PARAM_USE_COFACTOR_ECDH, NULL),
711 const OSSL_PARAM *ec_gettable_params(void)
713 return ec_known_gettable_params;
716 static const OSSL_PARAM ec_known_settable_params[] = {
717 OSSL_PARAM_int(OSSL_PKEY_PARAM_USE_COFACTOR_ECDH, NULL),
722 const OSSL_PARAM *ec_settable_params(void)
724 return ec_known_settable_params;
728 int ec_set_params(void *key, const OSSL_PARAM params[])
733 p = OSSL_PARAM_locate_const(params, OSSL_PKEY_PARAM_USE_COFACTOR_ECDH);
734 if (p != NULL && !ec_set_param_ecdh_cofactor_mode(eck, p))
741 int ec_validate(void *keydata, int selection)
743 EC_KEY *eck = keydata;
745 BN_CTX *ctx = BN_CTX_new_ex(ec_key_get_libctx(eck));
750 if ((selection & EC_POSSIBLE_SELECTIONS) != 0)
753 if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) != 0)
754 ok = ok && EC_GROUP_check(EC_KEY_get0_group(eck), ctx);
756 if ((selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0)
757 ok = ok && ec_key_public_check(eck, ctx);
759 if ((selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0)
760 ok = ok && ec_key_private_check(eck);
762 if ((selection & OSSL_KEYMGMT_SELECT_KEYPAIR) == OSSL_KEYMGMT_SELECT_KEYPAIR)
763 ok = ok && ec_key_pairwise_check(eck, ctx);
769 const OSSL_DISPATCH ec_keymgmt_functions[] = {
770 { OSSL_FUNC_KEYMGMT_NEW, (void (*)(void))ec_newdata },
771 { OSSL_FUNC_KEYMGMT_FREE, (void (*)(void))ec_freedata },
772 { OSSL_FUNC_KEYMGMT_GET_PARAMS, (void (*) (void))ec_get_params },
773 { OSSL_FUNC_KEYMGMT_GETTABLE_PARAMS, (void (*) (void))ec_gettable_params },
774 { OSSL_FUNC_KEYMGMT_SET_PARAMS, (void (*) (void))ec_set_params },
775 { OSSL_FUNC_KEYMGMT_SETTABLE_PARAMS, (void (*) (void))ec_settable_params },
776 { OSSL_FUNC_KEYMGMT_HAS, (void (*)(void))ec_has },
777 { OSSL_FUNC_KEYMGMT_MATCH, (void (*)(void))ec_match },
778 { OSSL_FUNC_KEYMGMT_VALIDATE, (void (*)(void))ec_validate },
779 { OSSL_FUNC_KEYMGMT_IMPORT, (void (*)(void))ec_import },
780 { OSSL_FUNC_KEYMGMT_IMPORT_TYPES, (void (*)(void))ec_import_types },
781 { OSSL_FUNC_KEYMGMT_EXPORT, (void (*)(void))ec_export },
782 { OSSL_FUNC_KEYMGMT_EXPORT_TYPES, (void (*)(void))ec_export_types },
783 { OSSL_FUNC_KEYMGMT_QUERY_OPERATION_NAME,
784 (void (*)(void))ec_query_operation_name },