=head1 SYNOPSIS
#include <openssl/dh.h>
-
- void DH_set_default_method(DH_METHOD *meth);
- DH_METHOD *DH_get_default_method(void);
- DH_METHOD *DH_set_method(DH *dh, DH_METHOD *meth);
- DH *DH_new_method(DH_METHOD *meth);
- DH_METHOD *DH_OpenSSL(void);
+ #include <openssl/engine.h>
DH * DH_new(void);
void DH_free(DH *dh);
- int DH_size(DH *dh);
-
- int DH_get_ex_new_index(long argl, char *argp, int (*new_func)(),
- int (*dup_func)(), void (*free_func)());
- int DH_set_ex_data(DH *d, int idx, char *arg);
- char *DH_get_ex_data(DH *d, int idx);
+ int DH_size(const DH *dh);
DH * DH_generate_parameters(int prime_len, int generator,
void (*callback)(int, int, void *), void *cb_arg);
- int DH_check(DH *dh, int *codes);
+ int DH_check(const DH *dh, int *codes);
int DH_generate_key(DH *dh);
int DH_compute_key(unsigned char *key, BIGNUM *pub_key, DH *dh);
+ void DH_set_default_method(const DH_METHOD *meth);
+ const DH_METHOD *DH_get_default_method(void);
+ int DH_set_method(DH *dh, const DH_METHOD *meth);
+ DH *DH_new_method(ENGINE *engine);
+ const DH_METHOD *DH_OpenSSL(void);
+
+ int DH_get_ex_new_index(long argl, char *argp, int (*new_func)(),
+ int (*dup_func)(), void (*free_func)());
+ int DH_set_ex_data(DH *d, int idx, char *arg);
+ char *DH_get_ex_data(DH *d, int idx);
+
DH * d2i_DHparams(DH **a, unsigned char **pp, long length);
- int i2d_DHparams(DH *a, unsigned char **pp);
+ int i2d_DHparams(const DH *a, unsigned char **pp);
- int DHparams_print_fp(FILE *fp, DH *x);
- int DHparams_print(BIO *bp, DH *x);
+ int DHparams_print_fp(FILE *fp, const DH *x);
+ int DHparams_print(BIO *bp, const DH *x);
=head1 DESCRIPTION
These functions implement the Diffie-Hellman key agreement protocol.
The generation of shared DH parameters is described in
-L<DH_generate_parameters(3)>; L<DH_generate_key(3)> describes how
+L<DH_generate_parameters(3)|DH_generate_parameters(3)>; L<DH_generate_key(3)|DH_generate_key(3)> describes how
to perform a key agreement.
The B<DH> structure consists of several BIGNUM components.
BIGNUM *g; // generator of Z_p (shared)
BIGNUM *priv_key; // private DH value x
BIGNUM *pub_key; // public DH value g^x
- // ...
+ // ...
};
DH
+Note that DH keys may use non-standard B<DH_METHOD> implementations,
+either directly or by the use of B<ENGINE> modules. In some cases (eg. an
+ENGINE providing support for hardware-embedded keys), these BIGNUM values
+will not be used by the implementation or may be used for alternative data
+storage. For this reason, applications should generally avoid using DH
+structure elements directly and instead use API functions to query or
+modify keys.
+
=head1 SEE ALSO
-dhparam(1), bn(3), dsa(3), err(3), rand(3), rsa(3), DH_set_method(3),
-DH_new(3), DH_get_ex_new_index(3), DH_generate_parameters(3),
-DH_compute_key(3), d2i_DHparams(3), DHparams_print(3)
+L<dhparam(1)|dhparam(1)>, L<bn(3)|bn(3)>, L<dsa(3)|dsa(3)>, L<err(3)|err(3)>,
+L<rand(3)|rand(3)>, L<rsa(3)|rsa(3)>, L<engine(3)|engine(3)>,
+L<DH_set_method(3)|DH_set_method(3)>, L<DH_new(3)|DH_new(3)>,
+L<DH_get_ex_new_index(3)|DH_get_ex_new_index(3)>,
+L<DH_generate_parameters(3)|DH_generate_parameters(3)>,
+L<DH_compute_key(3)|DH_compute_key(3)>, L<d2i_DHparams(3)|d2i_DHparams(3)>,
+L<RSA_print(3)|RSA_print(3)>
=cut