/* * Copyright 2020 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 */ /* * ECDH/ECDSA low level APIs are deprecated for public use, but still ok for * internal use. */ #include "internal/deprecated.h" #include #include #include #include #include #include #include "crypto/bn.h" #include "internal/param_build.h" #include "prov/implementations.h" #include "prov/providercommon.h" static OSSL_OP_keymgmt_new_fn ec_newdata; static OSSL_OP_keymgmt_free_fn ec_freedata; static OSSL_OP_keymgmt_get_params_fn ec_get_params; static OSSL_OP_keymgmt_gettable_params_fn ec_gettable_params; static OSSL_OP_keymgmt_set_params_fn ec_set_params; static OSSL_OP_keymgmt_settable_params_fn ec_settable_params; static OSSL_OP_keymgmt_has_fn ec_has; static OSSL_OP_keymgmt_match_fn ec_match; static OSSL_OP_keymgmt_import_fn ec_import; static OSSL_OP_keymgmt_import_types_fn ec_import_types; static OSSL_OP_keymgmt_export_fn ec_export; static OSSL_OP_keymgmt_export_types_fn ec_export_types; static OSSL_OP_keymgmt_query_operation_name_fn ec_query_operation_name; #define EC_POSSIBLE_SELECTIONS \ (OSSL_KEYMGMT_SELECT_KEYPAIR | OSSL_KEYMGMT_SELECT_ALL_PARAMETERS ) static const char *ec_query_operation_name(int operation_id) { switch (operation_id) { case OSSL_OP_KEYEXCH: return "ECDH"; #if 0 case OSSL_OP_SIGNATURE: return deflt_signature; #endif } return NULL; } static ossl_inline int params_to_domparams(EC_KEY *ec, const OSSL_PARAM params[]) { const OSSL_PARAM *param_ec_name; EC_GROUP *ecg = NULL; char *curve_name = NULL; int ok = 0; if (ec == NULL) return 0; param_ec_name = OSSL_PARAM_locate_const(params, OSSL_PKEY_PARAM_EC_NAME); if (param_ec_name == NULL) { /* explicit parameters */ /* * TODO(3.0): should we support explicit parameters curves? */ return 0; } else { /* named curve */ int curve_nid; if (!OSSL_PARAM_get_utf8_string(param_ec_name, &curve_name, 0) || curve_name == NULL || (curve_nid = OBJ_sn2nid(curve_name)) == NID_undef) goto err; if ((ecg = EC_GROUP_new_by_curve_name(curve_nid)) == NULL) goto err; } if (!EC_KEY_set_group(ec, ecg)) goto err; /* * TODO(3.0): if the group has changed, should we invalidate the private and * public key? */ ok = 1; err: OPENSSL_free(curve_name); EC_GROUP_free(ecg); return ok; } static ossl_inline int domparams_to_params(const EC_KEY *ec, OSSL_PARAM_BLD *tmpl) { const EC_GROUP *ecg; int curve_nid; if (ec == NULL) return 0; ecg = EC_KEY_get0_group(ec); if (ecg == NULL) return 0; curve_nid = EC_GROUP_get_curve_name(ecg); if (curve_nid == NID_undef) { /* explicit parameters */ /* * TODO(3.0): should we support explicit parameters curves? */ return 0; } else { /* named curve */ const char *curve_name = NULL; if ((curve_name = OBJ_nid2sn(curve_nid)) == NULL) return 0; if (!ossl_param_bld_push_utf8_string(tmpl, OSSL_PKEY_PARAM_EC_NAME, curve_name, 0)) return 0; } return 1; } /* * Callers of params_to_key MUST make sure that params_to_domparams has been * called before! * * This function only imports the bare keypair, domain parameters and other * parameters are imported separately, and domain parameters are required to * define a keypair. */ static ossl_inline int params_to_key(EC_KEY *ec, const OSSL_PARAM params[], int include_private) { const OSSL_PARAM *param_priv_key, *param_pub_key; BIGNUM *priv_key = NULL; unsigned char *pub_key = NULL; size_t pub_key_len; const EC_GROUP *ecg = NULL; EC_POINT *pub_point = NULL; int ok = 0; ecg = EC_KEY_get0_group(ec); if (ecg == NULL) return 0; param_priv_key = OSSL_PARAM_locate_const(params, OSSL_PKEY_PARAM_PRIV_KEY); param_pub_key = OSSL_PARAM_locate_const(params, OSSL_PKEY_PARAM_PUB_KEY); /* * We want to have at least a public key either way, so we end up * requiring it unconditionally. */ if (param_pub_key == NULL || !OSSL_PARAM_get_octet_string(param_pub_key, (void **)&pub_key, 0, &pub_key_len) || (pub_point = EC_POINT_new(ecg)) == NULL || !EC_POINT_oct2point(ecg, pub_point, pub_key, pub_key_len, NULL)) goto err; if (param_priv_key != NULL && include_private) { int fixed_top; const BIGNUM *order; /* * Key import/export should never leak the bit length of the secret * scalar in the key. * * For this reason, on export we use padded BIGNUMs with fixed length. * * When importing we also should make sure that, even if short lived, * the newly created BIGNUM is marked with the BN_FLG_CONSTTIME flag as * soon as possible, so that any processing of this BIGNUM might opt for * constant time implementations in the backend. * * Setting the BN_FLG_CONSTTIME flag alone is never enough, we also have * to preallocate the BIGNUM internal buffer to a fixed public size big * enough that operations performed during the processing never trigger * a realloc which would leak the size of the scalar through memory * accesses. * * Fixed Length * ------------ * * The order of the large prime subgroup of the curve is our choice for * a fixed public size, as that is generally the upper bound for * generating a private key in EC cryptosystems and should fit all valid * secret scalars. * * For padding on export we just use the bit length of the order * converted to bytes (rounding up). * * For preallocating the BIGNUM storage we look at the number of "words" * required for the internal representation of the order, and we * preallocate 2 extra "words" in case any of the subsequent processing * might temporarily overflow the order length. */ order = EC_GROUP_get0_order(ecg); if (order == NULL || BN_is_zero(order)) goto err; fixed_top = bn_get_top(order) + 2; if ((priv_key = BN_new()) == NULL) goto err; if (bn_wexpand(priv_key, fixed_top) == NULL) goto err; BN_set_flags(priv_key, BN_FLG_CONSTTIME); if (!OSSL_PARAM_get_BN(param_priv_key, &priv_key)) goto err; } if (priv_key != NULL && !EC_KEY_set_private_key(ec, priv_key)) goto err; if (!EC_KEY_set_public_key(ec, pub_point)) goto err; ok = 1; err: BN_clear_free(priv_key); OPENSSL_free(pub_key); EC_POINT_free(pub_point); return ok; } /* * Callers of key_to_params MUST make sure that domparams_to_params is also * called! * * This function only exports the bare keypair, domain parameters and other * parameters are exported separately. */ static ossl_inline int key_to_params(const EC_KEY *eckey, OSSL_PARAM_BLD *tmpl, int include_private) { const BIGNUM *priv_key = NULL; const EC_POINT *pub_point = NULL; const EC_GROUP *ecg = NULL; unsigned char *pub_key = NULL; size_t pub_key_len = 0; int ret = 0; if (eckey == NULL) return 0; ecg = EC_KEY_get0_group(eckey); priv_key = EC_KEY_get0_private_key(eckey); pub_point = EC_KEY_get0_public_key(eckey); /* group and public_key must be present, priv_key is optional */ if (ecg == NULL || pub_point == NULL) return 0; if ((pub_key_len = EC_POINT_point2buf(ecg, pub_point, POINT_CONVERSION_COMPRESSED, &pub_key, NULL)) == 0) return 0; if (!ossl_param_bld_push_octet_string(tmpl, OSSL_PKEY_PARAM_PUB_KEY, pub_key, pub_key_len)) goto err; if (priv_key != NULL && include_private) { size_t sz; int ecbits; /* * Key import/export should never leak the bit length of the secret * scalar in the key. * * For this reason, on export we use padded BIGNUMs with fixed length. * * When importing we also should make sure that, even if short lived, * the newly created BIGNUM is marked with the BN_FLG_CONSTTIME flag as * soon as possible, so that any processing of this BIGNUM might opt for * constant time implementations in the backend. * * Setting the BN_FLG_CONSTTIME flag alone is never enough, we also have * to preallocate the BIGNUM internal buffer to a fixed public size big * enough that operations performed during the processing never trigger * a realloc which would leak the size of the scalar through memory * accesses. * * Fixed Length * ------------ * * The order of the large prime subgroup of the curve is our choice for * a fixed public size, as that is generally the upper bound for * generating a private key in EC cryptosystems and should fit all valid * secret scalars. * * For padding on export we just use the bit length of the order * converted to bytes (rounding up). * * For preallocating the BIGNUM storage we look at the number of "words" * required for the internal representation of the order, and we * preallocate 2 extra "words" in case any of the subsequent processing * might temporarily overflow the order length. */ ecbits = EC_GROUP_order_bits(ecg); if (ecbits <= 0) goto err; sz = (ecbits + 7 ) / 8; if (!ossl_param_bld_push_BN_pad(tmpl, OSSL_PKEY_PARAM_PRIV_KEY, priv_key, sz)) goto err; } ret = 1; err: OPENSSL_free(pub_key); return ret; } static ossl_inline int ec_set_param_ecdh_cofactor_mode(EC_KEY *ec, const OSSL_PARAM *p) { const EC_GROUP *ecg = EC_KEY_get0_group(ec); const BIGNUM *cofactor; int mode; if (!OSSL_PARAM_get_int(p, &mode)) return 0; /* * mode can be only 0 for disable, or 1 for enable here. * * This is in contrast with the same parameter on an ECDH EVP_PKEY_CTX that * also supports mode == -1 with the meaning of "reset to the default for * the associated key". */ if (mode < 0 || mode > 1) return 0; if ((cofactor = EC_GROUP_get0_cofactor(ecg)) == NULL ) return 0; /* ECDH cofactor mode has no effect if cofactor is 1 */ if (BN_is_one(cofactor)) return 1; if (mode == 1) EC_KEY_set_flags(ec, EC_FLAG_COFACTOR_ECDH); else if (mode == 0) EC_KEY_clear_flags(ec, EC_FLAG_COFACTOR_ECDH); return 1; } static ossl_inline int params_to_otherparams(EC_KEY *ec, const OSSL_PARAM params[]) { const OSSL_PARAM *p; if (ec == NULL) return 0; p = OSSL_PARAM_locate_const(params, OSSL_PKEY_PARAM_USE_COFACTOR_ECDH); if (p != NULL && !ec_set_param_ecdh_cofactor_mode(ec, p)) return 0; return 1; } static ossl_inline int otherparams_to_params(const EC_KEY *ec, OSSL_PARAM_BLD *tmpl) { int ecdh_cofactor_mode = 0; if (ec == NULL) return 0; ecdh_cofactor_mode = (EC_KEY_get_flags(ec) & EC_FLAG_COFACTOR_ECDH) ? 1 : 0; if (!ossl_param_bld_push_int(tmpl, OSSL_PKEY_PARAM_USE_COFACTOR_ECDH, ecdh_cofactor_mode)) return 0; return 1; } static void *ec_newdata(void *provctx) { return EC_KEY_new(); } static void ec_freedata(void *keydata) { EC_KEY_free(keydata); } static int ec_has(void *keydata, int selection) { EC_KEY *ec = keydata; int ok = 0; if ((selection & EC_POSSIBLE_SELECTIONS) != 0) ok = 1; if ((selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0) ok = ok && (EC_KEY_get0_public_key(ec) != NULL); if ((selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0) ok = ok && (EC_KEY_get0_private_key(ec) != NULL); if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) != 0) ok = ok && (EC_KEY_get0_group(ec) != NULL); /* * We consider OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS to always be available, * so no extra check is needed other than the previous one against * EC_POSSIBLE_SELECTIONS. */ return ok; } static int ec_match(const void *keydata1, const void *keydata2, int selection) { const EC_KEY *ec1 = keydata1; const EC_KEY *ec2 = keydata2; const EC_GROUP *group_a = EC_KEY_get0_group(ec1); const EC_GROUP *group_b = EC_KEY_get0_group(ec2); int ok = 1; if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) != 0) ok = ok && group_a != NULL && group_b != NULL && EC_GROUP_cmp(group_a, group_b, NULL) == 0; if ((selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0) { const BIGNUM *pa = EC_KEY_get0_private_key(ec1); const BIGNUM *pb = EC_KEY_get0_private_key(ec2); ok = ok && BN_cmp(pa, pb) == 0; } if ((selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0) { const EC_POINT *pa = EC_KEY_get0_public_key(ec1); const EC_POINT *pb = EC_KEY_get0_public_key(ec2); ok = ok && EC_POINT_cmp(group_b, pa, pb, NULL); } return ok; } static int ec_import(void *keydata, int selection, const OSSL_PARAM params[]) { EC_KEY *ec = keydata; int ok = 1; if (ec == NULL) return 0; /* * In this implementation, we can export/import only keydata in the * following combinations: * - domain parameters only * - public key with associated domain parameters (+optional other params) * - private key with associated public key and domain parameters * (+optional other params) * * This means: * - domain parameters must always be requested * - private key must be requested alongside public key * - other parameters must be requested only alongside a key */ if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) == 0) return 0; if ((selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0 && (selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) == 0) return 0; if ((selection & OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS) != 0 && (selection & OSSL_KEYMGMT_SELECT_KEYPAIR) == 0) return 0; if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) != 0) ok = ok && params_to_domparams(ec, params); if ((selection & OSSL_KEYMGMT_SELECT_KEYPAIR) != 0) { int include_private = selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY ? 1 : 0; ok = ok && params_to_key(ec, params, include_private); } if ((selection & OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS) != 0) ok = ok && params_to_otherparams(ec, params); return ok; } static int ec_export(void *keydata, int selection, OSSL_CALLBACK *param_cb, void *cbarg) { EC_KEY *ec = keydata; OSSL_PARAM_BLD tmpl; OSSL_PARAM *params = NULL; int ok = 1; if (ec == NULL) return 0; /* * In this implementation, we can export/import only keydata in the * following combinations: * - domain parameters only * - public key with associated domain parameters (+optional other params) * - private key with associated public key and domain parameters * (+optional other params) * * This means: * - domain parameters must always be requested * - private key must be requested alongside public key * - other parameters must be requested only alongside a key */ if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) == 0) return 0; if ((selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0 && (selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) == 0) return 0; if ((selection & OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS) != 0 && (selection & OSSL_KEYMGMT_SELECT_KEYPAIR) == 0) return 0; ossl_param_bld_init(&tmpl); if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) != 0) ok = ok && domparams_to_params(ec, &tmpl); if ((selection & OSSL_KEYMGMT_SELECT_KEYPAIR) != 0) { int include_private = selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY ? 1 : 0; ok = ok && key_to_params(ec, &tmpl, include_private); } if ((selection & OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS) != 0) ok = ok && otherparams_to_params(ec, &tmpl); if (!ok || (params = ossl_param_bld_to_param(&tmpl)) == NULL) return 0; ok = param_cb(params, cbarg); ossl_param_bld_free(params); return ok; } /* IMEXPORT = IMPORT + EXPORT */ # define EC_IMEXPORTABLE_DOM_PARAMETERS \ OSSL_PARAM_utf8_string(OSSL_PKEY_PARAM_EC_NAME, NULL, 0) # define EC_IMEXPORTABLE_PUBLIC_KEY \ OSSL_PARAM_octet_string(OSSL_PKEY_PARAM_PUB_KEY, NULL, 0) # define EC_IMEXPORTABLE_PRIVATE_KEY \ OSSL_PARAM_BN(OSSL_PKEY_PARAM_PRIV_KEY, NULL, 0) # define EC_IMEXPORTABLE_OTHER_PARAMETERS \ OSSL_PARAM_int(OSSL_PKEY_PARAM_USE_COFACTOR_ECDH, NULL) /* * Include all the possible combinations of OSSL_PARAM arrays for * ec_imexport_types(). * * They are in a separate file as it is ~100 lines of unreadable and * uninteresting machine generated stuff. * * TODO(3.0): the generated list looks quite ugly, as to cover all possible * combinations of the bits in `selection`, it also includes combinations that * are not really useful: we might want to consider alternatives to this * solution. */ #include "ec_kmgmt_imexport.inc" static ossl_inline const OSSL_PARAM *ec_imexport_types(int selection) { int type_select = 0; if ((selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0) type_select += 1; if ((selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0) type_select += 2; if ((selection & OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS) != 0) type_select += 4; if ((selection & OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS) != 0) type_select += 8; return ec_types[type_select]; } static const OSSL_PARAM *ec_import_types(int selection) { return ec_imexport_types(selection); } static const OSSL_PARAM *ec_export_types(int selection) { return ec_imexport_types(selection); } static int ec_get_params(void *key, OSSL_PARAM params[]) { EC_KEY *eck = key; const EC_GROUP *ecg = NULL; OSSL_PARAM *p; ecg = EC_KEY_get0_group(eck); if (ecg == NULL) return 0; if ((p = OSSL_PARAM_locate(params, OSSL_PKEY_PARAM_MAX_SIZE)) != NULL && !OSSL_PARAM_set_int(p, ECDSA_size(eck))) return 0; if ((p = OSSL_PARAM_locate(params, OSSL_PKEY_PARAM_BITS)) != NULL && !OSSL_PARAM_set_int(p, EC_GROUP_order_bits(ecg))) return 0; if ((p = OSSL_PARAM_locate(params, OSSL_PKEY_PARAM_SECURITY_BITS)) != NULL) { int ecbits, sec_bits; ecbits = EC_GROUP_order_bits(ecg); /* * The following estimates are based on the values published * in Table 2 of "NIST Special Publication 800-57 Part 1 Revision 4" * at http://dx.doi.org/10.6028/NIST.SP.800-57pt1r4 . * * Note that the above reference explicitly categorizes algorithms in a * discrete set of values {80, 112, 128, 192, 256}, and that it is * relevant only for NIST approved Elliptic Curves, while OpenSSL * applies the same logic also to other curves. * * Classifications produced by other standardazing bodies might differ, * so the results provided for "bits of security" by this provider are * to be considered merely indicative, and it is the users' * responsibility to compare these values against the normative * references that may be relevant for their intent and purposes. */ if (ecbits >= 512) sec_bits = 256; else if (ecbits >= 384) sec_bits = 192; else if (ecbits >= 256) sec_bits = 128; else if (ecbits >= 224) sec_bits = 112; else if (ecbits >= 160) sec_bits = 80; else sec_bits = ecbits / 2; if (!OSSL_PARAM_set_int(p, sec_bits)) return 0; } p = OSSL_PARAM_locate(params, OSSL_PKEY_PARAM_USE_COFACTOR_ECDH); if (p != NULL) { int ecdh_cofactor_mode = 0; ecdh_cofactor_mode = (EC_KEY_get_flags(eck) & EC_FLAG_COFACTOR_ECDH) ? 1 : 0; if (!OSSL_PARAM_set_int(p, ecdh_cofactor_mode)) return 0; } return 1; } static const OSSL_PARAM ec_known_gettable_params[] = { OSSL_PARAM_int(OSSL_PKEY_PARAM_BITS, NULL), OSSL_PARAM_int(OSSL_PKEY_PARAM_SECURITY_BITS, NULL), OSSL_PARAM_int(OSSL_PKEY_PARAM_MAX_SIZE, NULL), OSSL_PARAM_int(OSSL_PKEY_PARAM_USE_COFACTOR_ECDH, NULL), OSSL_PARAM_END }; static const OSSL_PARAM *ec_gettable_params(void) { return ec_known_gettable_params; } static const OSSL_PARAM ec_known_settable_params[] = { OSSL_PARAM_int(OSSL_PKEY_PARAM_USE_COFACTOR_ECDH, NULL), OSSL_PARAM_END }; static const OSSL_PARAM *ec_settable_params(void) { return ec_known_settable_params; } static int ec_set_params(void *key, const OSSL_PARAM params[]) { EC_KEY *eck = key; const OSSL_PARAM *p; p = OSSL_PARAM_locate_const(params, OSSL_PKEY_PARAM_USE_COFACTOR_ECDH); if (p != NULL && !ec_set_param_ecdh_cofactor_mode(eck, p)) return 0; return 1; } const OSSL_DISPATCH ec_keymgmt_functions[] = { { OSSL_FUNC_KEYMGMT_NEW, (void (*)(void))ec_newdata }, { OSSL_FUNC_KEYMGMT_FREE, (void (*)(void))ec_freedata }, { OSSL_FUNC_KEYMGMT_GET_PARAMS, (void (*) (void))ec_get_params }, { OSSL_FUNC_KEYMGMT_GETTABLE_PARAMS, (void (*) (void))ec_gettable_params }, { OSSL_FUNC_KEYMGMT_SET_PARAMS, (void (*) (void))ec_set_params }, { OSSL_FUNC_KEYMGMT_SETTABLE_PARAMS, (void (*) (void))ec_settable_params }, { OSSL_FUNC_KEYMGMT_HAS, (void (*)(void))ec_has }, { OSSL_FUNC_KEYMGMT_MATCH, (void (*)(void))ec_match }, { OSSL_FUNC_KEYMGMT_IMPORT, (void (*)(void))ec_import }, { OSSL_FUNC_KEYMGMT_IMPORT_TYPES, (void (*)(void))ec_import_types }, { OSSL_FUNC_KEYMGMT_EXPORT, (void (*)(void))ec_export }, { OSSL_FUNC_KEYMGMT_EXPORT_TYPES, (void (*)(void))ec_export_types }, { OSSL_FUNC_KEYMGMT_QUERY_OPERATION_NAME, (void (*)(void))ec_query_operation_name }, { 0, NULL } };