openssl_dh(3)
- NetBSD Manual Pages
dh(3) OpenSSL dh(3)
NAME
dh - Diffie-Hellman key agreement
LIBRARY
libcrypto, -lcrypto
SYNOPSIS
#include <openssl/dh.h>
#include <openssl/engine.h>
DH * DH_new(void);
void DH_free(DH *dh);
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(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(const DH *a, unsigned char **pp);
int DHparams_print_fp(FILE *fp, const DH *x);
int DHparams_print(BIO *bp, const DH *x);
DESCRIPTION
These functions implement the Diffie-Hellman key agreement protocol.
The generation of shared DH parameters is described in DH_gener-
ate_parameters(3); DH_generate_key(3) describes how to perform a key
agreement.
The DH structure consists of several BIGNUM components.
struct
{
BIGNUM *p; // prime number (shared)
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 DH_METHOD implementations,
either directly or by the use of ENGINE modules. In some cases (eg. an
ENGINE providing support for hardware-embedded keys), these BIGNUM val-
ues will not be used by the implementation or may be used for alterna-
tive data storage. For this reason, applications should generally avoid
using DH structure elements directly and instead use API functions to
query or modify keys.
SEE ALSO
openssl_dhparam(1), openssl_bn(3), openssl_dsa(3), openssl_err(3),
openssl_rand(3), openssl_rsa(3), engine(3), DH_set_method(3),
DH_new(3), DH_get_ex_new_index(3), DH_generate_parameters(3), DH_com-
pute_key(3), d2i_DHparams(3), RSA_print(3)
0.9.9-dev 2003-07-24 dh(3)
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