/* Key Exchange parameters */
int OP_keyexch_set_ctx_params(void *ctx, const OSSL_PARAM params[]);
const OSSL_PARAM *OP_keyexch_settable_ctx_params(void);
+ int OP_keyexch_get_ctx_params(void *ctx, OSSL_PARAM params[]);
+ const OSSL_PARAM *OP_keyexch_gettable_ctx_params(void);
=head1 DESCRIPTION
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<EVP_PKEY_derive_init_ex(3)>, and L<EVP_PKEY_derive(3)> (as well as
+exchange algorithms and make them available to applications via
+L<EVP_PKEY_derive(3)> and
other related functions).
All "functions" mentioned here are passed as function pointers between
OP_keyexch_set_ctx_params OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS
OP_keyexch_settable_ctx_params OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS
+ OP_keyexch_get_ctx_params OSSL_FUNC_KEYEXCH_GET_CTX_PARAMS
+ OP_keyexch_gettable_ctx_params OSSL_FUNC_KEYEXCH_GETTABLE_CTX_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
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 param
ater I<provctx> is the provider context generated during provider
+The param
eter I<provctx> is the provider context generated during provider
initialisation (see L<provider(7)>).
OP_keyexch_freectx() is passed a pointer to the provider side key exchange
=head2 Shared Secret Derivation Functions
OP_keyexch_init() initialises a key exchange operation given a provider side key
-exchange context in the I<ctx> paramter, and a pointer to a provider key object
+exchange context in the I<ctx> parameter, and a pointer to a provider key object
in the I<provkey> 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)>.
If I<secret> is NULL then the maximum length of the shared secret should be
written to I<*secretlen>.
-=head2 Key Exchange Parameters
-
-See L<OSSL_PARAM(3)> for further details on the parameters structure used by
-the OP_keyexch_set_params() function.
+=head2 Key Exchange Parameters Functions
OP_keyexch_set_ctx_params() sets key exchange parameters associated with the
-given provider side key exchange context I<ctx> to I<params>.
+given provider side key exchange context I<ctx> to I<params>,
+see L</Key Exchange Parameters>.
Any parameter settings are additional to any that were previously set.
+OP_keyexch_get_ctx_params() gets key exchange parameters associated with the
+given provider side key exchange context I<ctx> into I<params>,
+see L</Key Exchange Parameters>.
+
+OP_keyexch_settable_ctx_params() yields a constant B<OSSL_PARAM> array that
+describes the settable parameters, i.e. parameters that can be used with
+OP_signature_set_ctx_params().
+If OP_keyexch_settable_ctx_params() is present, OP_keyexch_set_ctx_params() must
+also be present, and vice versa.
+Similarly, OP_keyexch_gettable_ctx_params() yields a constant B<OSSL_PARAM>
+array that describes the gettable parameters, i.e. parameters that can be
+handled by OP_signature_get_ctx_params().
+If OP_keyexch_gettable_ctx_params() is present, OP_keyexch_get_ctx_params() must
+also be present, and vice versa.
+See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.
+
+Notice that not all settable parameters are also gettable, and vice versa.
+
+=head2 Key Exchange Parameters
+
+See L<OSSL_PARAM(3)> for further details on the parameters structure used by
+the OP_keyexch_set_ctx_params() and OP_keyexch_get_ctx_params() functions.
+
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
with 0s where necessary to make the shared secret the same size as the largest
possible secret size.
-=back
+=item "ecdh-cofactor-mode" (B<OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE>) <integer>
-OP_keyexch_settable_ctx_params() gets a constant B<OSSL_PARAM> array that
-decribes the settable parameters, i.e. parameters that can be used with
-OP_signature_set_ctx_params().
-See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.
+Sets/gets the ECDH mode of operation for the associated key exchange ctx.
+
+In the context of an Elliptic Curve Diffie-Hellman key exchange, this parameter
+can be used to select between the plain Diffie-Hellman (DH) or Cofactor
+Diffie-Hellman (CDH) variants of the key exchange algorithm.
+
+When setting, the value should be 1, 0 or -1, respectively forcing cofactor mode
+on, off, or resetting it to the default for the private key associated with the
+given key exchange ctx.
+
+When getting, the value should be either 1 or 0, respectively signaling if the
+cofactor mode is on or off.
+
+See also L<provider-keymgmt(7)> for the related
+B<OSSL_PKEY_PARAM_USE_COFACTOR_ECDH> parameter that can be set on a
+per-key basis.
+
+=item "kdf-type" (B<OSSL_EXCHANGE_PARAM_KDF_TYPE>) <utf8_string>
+
+Sets/gets the Key Derivation Function type to apply within the associated key
+exchange ctx.
+
+=item "kdf-digest" (B<OSSL_EXCHANGE_PARAM_KDF_DIGEST>) <utf8_string>
+
+Sets/gets the Digest algorithm to be used as part of the Key Derivation Function
+associated with the given key exchange ctx.
+
+=item "kdf-digest-props" (B<OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS>) <utf8_string>
+
+Sets properties to be used upon look up of the implementation for the selected
+Digest algorithm for the Key Derivation Function associated with the given key
+exchange ctx.
+
+=item "kdf-outlen" (B<OSSL_EXCHANGE_PARAM_KDF_OUTLEN>) <size_t>
+
+Sets/gets the desired size for the output of the chosen Key Derivation Function
+associated with the given key exchange ctx.
+
+=item "kdf-ukm" (B<OSSL_EXCHANGE_PARAM_KDF_UKM>) <octet_string>
+
+Sets/gets User Key Material to be used as part of the selected Key Derivation
+Function associated with the given key exchange ctx.
+
+=item "kdf-ukm-len" (B<OSSL_EXCHANGE_PARAM_KDF_UKM_LEN>) <size_t>
+
+Sets/gets the size of the User Key Material to be used as part of the selected
+Key Derivation Function associated with the given key exchange ctx.
+
+=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.
+OP_keyexch_init(), OP_keyexch_set_peer(), OP_keyexch_derive(),
+OP_keyexch_set_params(), and OP_keyexch_get_params() should return 1 for success
+or 0 on error.
+
+OP_keyexch_settable_ctx_params() and OP_keyexch_gettable_ctx_params() should
+always return a constant B<OSSL_PARAM> array.
=head1 SEE ALSO
=head1 COPYRIGHT
-Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
+Copyright 2019-2020 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
projects / openssl.git / blobdiff