From: Matt Caswell Date: Mon, 29 Jul 2019 09:24:44 +0000 (+0100) Subject: Documentation for the provider Key Exchange operation X-Git-Tag: openssl-3.0.0-alpha1~1675 X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=59972370e391d6f6314cee26529cbda41eb0a198;p=oweals%2Fopenssl.git Documentation for the provider Key Exchange operation Reviewed-by: Paul Dale (Merged from https://github.com/openssl/openssl/pull/9506) --- diff --git a/doc/man7/provider-keyexch.pod b/doc/man7/provider-keyexch.pod new file mode 100644 index 0000000000..875d6e267e --- /dev/null +++ b/doc/man7/provider-keyexch.pod @@ -0,0 +1,179 @@ +=pod + +=head1 NAME + +provider-keyexch - The keyexch library E-E provider functions + +=head1 SYNOPSIS + +=for comment multiple includes + + #include + #include + + /* + * None of these are actual functions, but are displayed like this for + * the function signatures for functions that are offered as function + * pointers in OSSL_DISPATCH arrays. + */ + + /* Context management */ + void *OP_keyexch_newctx(void *provctx); + void OP_keyexch_freectx(void *ctx); + void *OP_keyexch_dupctx(void *ctx); + + /* Shared secret derivation */ + int OP_keyexch_init(void *ctx, void *provkey); + int OP_keyexch_set_peer(void *ctx, void *provkey); + int OP_keyexch_derive(void *ctx, unsigned char *secret, size_t *secretlen, + size_t outlen); + + /* Key Exchange parameters */ + int OP_keyexch_set_params(void *ctx, const OSSL_PARAM params[]); + + +=head1 DESCRIPTION + +This documentation is primarily aimed at provider authors. See L +for further information. + +The key exchange (OSSL_OP_KEYEXCH) operation enables providers to implement key +exchange algorithms and make them available to applications via the API +functions L, and L (as well as +other related functions). + +All "functions" mentioned here are passed as function pointers between +F and the provider in B arrays via +B arrays that are returned by the provider's +provider_query_operation() function +(see L). + +All these "functions" have a corresponding function type definition +named B, and a helper function to retrieve the +function pointer from an B element named +B. +For example, the "function" OP_keyexch_newctx() has these: + + typedef void *(OSSL_OP_keyexch_newctx_fn)(void *provctx); + static ossl_inline OSSL_OP_keyexch_newctx_fn + OSSL_get_OP_keyexch_newctx(const OSSL_DISPATCH *opf); + +B arrays are indexed by numbers that are provided as +macros in L, as follows: + + OP_keyexch_newctx OSSL_FUNC_KEYEXCH_NEWCTX + OP_keyexch_freectx OSSL_FUNC_KEYEXCH_FREECTX + OP_keyexch_dupctx OSSL_FUNC_KEYEXCH_DUPCTX + + OP_keyexch_init OSSL_FUNC_KEYEXCH_INIT + OP_keyexch_set_peer OSSL_FUNC_KEYEXCH_SET_PEER + OP_keyexch_derive OSSL_FUNC_KEYEXCH_DERIVE + + OP_keyexch_set_params OSSL_FUNC_KEYEXCH_SET_PARAMS + +A key exchange algorithm implementation may not implement all of these functions. +In order to be a consistent set of functions a provider must implement +OP_keyexch_newctx, OP_keyexch_freectx, OP_keyexch_init and OP_keyexch_derive. +All other functions are optional. + +A key exchange algorithm must also implement some mechanism for generating, +loading or importing keys via the key management (OSSL_OP_KEYMGMT) operation. +See L for further details. + +=head2 Context Management Functions + +OP_keyexch_newctx() should create and return a pointer to a provider side +structure for holding context information during a key exchange operation. +A pointer to this context will be passed back in a number of the other key +exchange operation function calls. +The paramater B is the provider context generated during provider +initialisation (see L). + +OP_keyexch_freectx() is passed a pointer to the provider side key exchange +context in the B parameter. +This function should free any resources associated with that context. + +OP_keyexch_dupctx() should duplicate the provider side key exchange context in +the B parameter and return the duplicate copy. + +=head2 Shared Secret Derivation Functions + +OP_keyexch_init() initialises a key exchange operation given a provider side key +exchange context in the B paramter, and a pointer to a provider key object +in the B parameter. The key object should have been previously +generated, loaded or imported into the provider using the key management +(OSSL_OP_KEYMGMT) operation (see provider-keymgmt(7)>. + +OP_keyexch_set_peer() is called to supply the peer's public key (in the +B parameter) to be used when deriving the shared secret. +It is also passed a previously initialised key exchange context in the B +parameter. +The key object should have been previously generated, loaded or imported into +the provider using the key management (OSSL_OP_KEYMGMT) operation (see +provider-keymgmt(7)>. + +OP_keyexch_derive() performs the actual key exchange itself by deriving a shared +secret. +A previously initialised key exchange context is passed in the B +parameter. +The derived secret should be written to the location B which should not +exceed B bytes. +The length of the shared secret should be written to B<*secretlen>. +If B is NULL then the maximum length of the shared secret should be +written to B<*secretlen>. + +=head2 Key Exchange Parameters + +See L for further details on the parameters structure used by +the OP_keyexch_set_params() function. + +OP_keyexch_set_params() sets key exchange parameters associated with the given +provider side key exchange context B to B. +Any parameter settings are additional to any that were previously set. + +Parameters currently recognised by built-in key exchange algorithms are as +follows. +Not all parameters are relevant to, or are understood by all key exchange +algorithms: + +=over 4 + +=item B (int) + +Sets the padding mode for the associated key exchange ctx. +Setting a value of 1 will turn padding on. +Setting a vlue of 0 will turn padding off. +If padding is off then the derived shared secret may be smaller than the largest +possible secret size. +If padding is on then the derived shared secret will have its first bytes filled +with 0s where necessary to make the shared secret the same size as the largest +possible secret size. + +=back + +=head1 RETURN VALUES + +OP_keyexch_newctx() and OP_keyexch_dupctx() should return the newly created +provider side key exchange context, or NULL on failure. + +OP_keyexch_init(), OP_keyexch_set_peer(), OP_keyexch_derive() and +OP_keyexch_set_params() should return 1 for success or 0 on error. + +=head1 SEE ALSO + +L + +=head1 HISTORY + +The provider KEYEXCH interface was introduced in OpenSSL 3.0. + +=head1 COPYRIGHT + +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 +L. + +=cut diff --git a/include/openssl/core_numbers.h b/include/openssl/core_numbers.h index 0bbe92709c..f4c4a61ada 100644 --- a/include/openssl/core_numbers.h +++ b/include/openssl/core_numbers.h @@ -302,8 +302,8 @@ OSSL_CORE_MAKE_FUNC(const OSSL_PARAM *, OP_keymgmt_exportkey_types, (void)) OSSL_CORE_MAKE_FUNC(void *, OP_keyexch_newctx, (void *provctx)) OSSL_CORE_MAKE_FUNC(int, OP_keyexch_init, (void *ctx, void *provkey)) -OSSL_CORE_MAKE_FUNC(int, OP_keyexch_derive, (void *ctx, unsigned char *key, - size_t *keylen, size_t outlen)) +OSSL_CORE_MAKE_FUNC(int, OP_keyexch_derive, (void *ctx, unsigned char *secret, + size_t *secretlen, size_t outlen)) OSSL_CORE_MAKE_FUNC(int, OP_keyexch_set_peer, (void *ctx, void *provkey)) OSSL_CORE_MAKE_FUNC(void, OP_keyexch_freectx, (void *ctx)) OSSL_CORE_MAKE_FUNC(void *, OP_keyexch_dupctx, (void *ctx)) diff --git a/providers/common/exchange/dh_exch.c b/providers/common/exchange/dh_exch.c index 62041daab3..69980d8e97 100644 --- a/providers/common/exchange/dh_exch.c +++ b/providers/common/exchange/dh_exch.c @@ -60,7 +60,7 @@ static int dh_set_peer(void *vpdhctx, void *vdh) return 1; } -static int dh_derive(void *vpdhctx, unsigned char *key, size_t *keylen, +static int dh_derive(void *vpdhctx, unsigned char *secret, size_t *secretlen, size_t outlen) { PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx; @@ -73,20 +73,20 @@ static int dh_derive(void *vpdhctx, unsigned char *key, size_t *keylen, return 0; dhsize = (size_t)DH_size(pdhctx->dh); - if (key == NULL) { - *keylen = dhsize; + if (secret == NULL) { + *secretlen = dhsize; return 1; } if (outlen < dhsize) return 0; DH_get0_key(pdhctx->dhpeer, &pub_key, NULL); - ret = (pdhctx->pad) ? DH_compute_key_padded(key, pub_key, pdhctx->dh) - : DH_compute_key(key, pub_key, pdhctx->dh); + ret = (pdhctx->pad) ? DH_compute_key_padded(secret, pub_key, pdhctx->dh) + : DH_compute_key(secret, pub_key, pdhctx->dh); if (ret <= 0) return 0; - *keylen = ret; + *secretlen = ret; return 1; }