X-Git-Url: https://git.openssl.org/?p=openssl.git;a=blobdiff_plain;f=doc%2Fcrypto%2FDH_set_method.pod;h=cd75a9b5490f55c706e13f501ed3003780959d9b;hp=50254a9bd3e75b5554354633bb6340e39429f05e;hb=13c03c8d6da334bb1cde6ce4133e7c75b3b76947;hpb=bb075f883356589425b7e57f788c7498a83b0219 diff --git a/doc/crypto/DH_set_method.pod b/doc/crypto/DH_set_method.pod index 50254a9bd3..cd75a9b549 100644 --- a/doc/crypto/DH_set_method.pod +++ b/doc/crypto/DH_set_method.pod @@ -2,98 +2,84 @@ =head1 NAME -DH_set_default_method, DH_get_default_method, DH_set_method, -DH_new_method, DH_OpenSSL - Select RSA method +DH_set_default_method, DH_get_default_method, +DH_set_method, DH_new_method, DH_OpenSSL - select DH method =head1 SYNOPSIS #include - void DH_set_default_method(DH_METHOD *meth); + void DH_set_default_method(const DH_METHOD *meth); - DH_METHOD *DH_get_default_method(void); + const DH_METHOD *DH_get_default_method(void); - DH_METHOD *DH_set_method(DH *dh, DH_METHOD *meth); + int DH_set_method(DH *dh, const DH_METHOD *meth); - DH *DH_new_method(DH_METHOD *meth); + DH *DH_new_method(ENGINE *engine); - DH_METHOD *DH_OpenSSL(void); + const DH_METHOD *DH_OpenSSL(void); =head1 DESCRIPTION A B specifies the functions that OpenSSL uses for Diffie-Hellman operations. By modifying the method, alternative implementations -such as hardware accelerators may be used. +such as hardware accelerators may be used. IMPORTANT: See the NOTES section for +important information about how these DH API functions are affected by the use +of B API calls. -Initially, the default is to use the OpenSSL internal implementation. -DH_OpenSSL() returns a pointer to that method. +Initially, the default DH_METHOD is the OpenSSL internal implementation, as +returned by DH_OpenSSL(). -DH_set_default_method() makes B the default method for all B -structures created later. +DH_set_default_method() makes B the default method for all DH +structures created later. B: This is true only whilst no ENGINE has been set +as a default for DH, so this function is no longer recommended. -DH_get_default_method() returns a pointer to the current default -method. +DH_get_default_method() returns a pointer to the current default DH_METHOD. +However, the meaningfulness of this result is dependent on whether the ENGINE +API is being used, so this function is no longer recommended. -DH_set_method() selects B for all operations using the structure B. +DH_set_method() selects B to perform all operations using the key B. +This will replace the DH_METHOD used by the DH key and if the previous method +was supplied by an ENGINE, the handle to that ENGINE will be released during the +change. It is possible to have DH keys that only work with certain DH_METHOD +implementations (eg. from an ENGINE module that supports embedded +hardware-protected keys), and in such cases attempting to change the DH_METHOD +for the key can have unexpected results. -DH_get_method() returns a pointer to the method currently selected -for B. +DH_new_method() allocates and initializes a DH structure so that B will +be used for the DH operations. If B is NULL, the default ENGINE for DH +operations is used, and if no default ENGINE is set, the DH_METHOD controlled by +DH_set_default_method() is used. -DH_new_method() allocates and initializes a B structure so that -B will be used for the DH operations. If B is B, -the default method is used. - -=head1 THE DH_METHOD STRUCTURE - - typedef struct dh_meth_st - { - /* name of the implementation */ - const char *name; - - /* generate private and public DH values for key agreement */ - int (*generate_key)(DH *dh); - - /* compute shared secret */ - int (*compute_key)(unsigned char *key, BIGNUM *pub_key, DH *dh); - - /* compute r = a ^ p mod m. May be NULL */ - int (*bn_mod_exp)(DH *dh, BIGNUM *r, BIGNUM *a, const BIGNUM *p, - const BIGNUM *m, BN_CTX *ctx, - BN_MONT_CTX *m_ctx); - - /* called at DH_new */ - int (*init)(DH *dh); - - /* called at DH_free */ - int (*finish)(DH *dh); - - int flags; - - char *app_data; /* ?? */ - - } DH_METHOD; +A new DH_METHOD object may be constructed using DH_meth_new() (see +L). =head1 RETURN VALUES -DH_OpenSSL(), DH_get_default_method() and DH_get_method() return -pointers to the respective Bs. +DH_OpenSSL() and DH_get_default_method() return pointers to the respective +Bs. DH_set_default_method() returns no value. -DH_set_method() returns a pointer to the B previously -associated with B. +DH_set_method() returns non-zero if the provided B was successfully set as +the method for B (including unloading the ENGINE handle if the previous +method was supplied by an ENGINE). -DH_new_method() returns B and sets an error code that can be -obtained by L if the allocation fails. Otherwise it +DH_new_method() returns NULL and sets an error code that can be obtained by +L if the allocation fails. Otherwise it returns a pointer to the newly allocated structure. =head1 SEE ALSO -L, L +L, L, L + +=head1 COPYRIGHT -=head1 HISTORY +Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved. -DH_set_default_method(), DH_get_default_method(), DH_set_method(), -DH_new_method() and DH_OpenSSL() were added in OpenSSL 0.9.4. +Licensed under the OpenSSL license (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