=pod =head1 NAME dh - Diffie-Hellman key agreement =head1 SYNOPSIS #include <openssl/dh.h> DH * DH_new(void); void DH_free(DH *dh); int DH_size(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_generate_key(DH *dh); int DH_compute_key(unsigned char *key, BIGNUM *pub_key, DH *dh); 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); 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 DHparams_print_fp(FILE *fp, DH *x); int DHparams_print(BIO *bp, 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)|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. 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 =head1 SEE ALSO 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<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