doc/crypto/dh.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 dh - Diffie-Hellman key agreement
   6
   7 =head1 SYNOPSIS
   8
   9  #include <openssl/dh.h>
  10  #include <openssl/engine.h>
  11
  12  DH *   DH_new(void);
  13  void   DH_free(DH *dh);
  14
  15  int    DH_size(DH *dh);
  16
  17  DH *   DH_generate_parameters(int prime_len, int generator,
  18                 void (*callback)(int, int, void *), void *cb_arg);
  19  int    DH_check(DH *dh, int *codes);
  20
  21  int    DH_generate_key(DH *dh);
  22  int    DH_compute_key(unsigned char *key, BIGNUM *pub_key, DH *dh);
  23
  24  void DH_set_default_openssl_method(DH_METHOD *meth);
  25  DH_METHOD *DH_get_default_openssl_method(void);
  26  int DH_set_method(DH *dh, ENGINE *engine);
  27  DH *DH_new_method(ENGINE *engine);
  28  DH_METHOD *DH_OpenSSL(void);
  29
  30  int DH_get_ex_new_index(long argl, char *argp, int (*new_func)(),
  31              int (*dup_func)(), void (*free_func)());
  32  int DH_set_ex_data(DH *d, int idx, char *arg);
  33  char *DH_get_ex_data(DH *d, int idx);
  34
  35  DH *   d2i_DHparams(DH **a, unsigned char **pp, long length);
  36  int    i2d_DHparams(DH *a, unsigned char **pp);
  37
  38  int    DHparams_print_fp(FILE *fp, DH *x);
  39  int    DHparams_print(BIO *bp, DH *x);
  40
  41 =head1 DESCRIPTION
  42
  43 These functions implement the Diffie-Hellman key agreement protocol.
  44 The generation of shared DH parameters is described in
  45 L<DH_generate_parameters(3)|DH_generate_parameters(3)>; L<DH_generate_key(3)|DH_generate_key(3)> describes how
  46 to perform a key agreement.
  47
  48 The B<DH> structure consists of several BIGNUM components.
  49
  50  struct
  51         {
  52         BIGNUM *p;              // prime number (shared)
  53         BIGNUM *g;              // generator of Z_p (shared)
  54         BIGNUM *priv_key;       // private DH value x
  55         BIGNUM *pub_key;        // public DH value g^x
  56         // ...
  57         };
  58  DH
  59
  60 =head1 SEE ALSO
  61
  62 L<dhparam(1)|dhparam(1)>, L<bn(3)|bn(3)>, L<dsa(3)|dsa(3)>, L<err(3)|err(3)>,
  63 L<rand(3)|rand(3)>, L<rsa(3)|rsa(3)>, L<DH_set_method(3)|DH_set_method(3)>,
  64 L<DH_new(3)|DH_new(3)>, L<DH_get_ex_new_index(3)|DH_get_ex_new_index(3)>,
  65 L<DH_generate_parameters(3)|DH_generate_parameters(3)>,
  66 L<DH_compute_key(3)|DH_compute_key(3)>, L<d2i_DHparams(3)|d2i_DHparams(3)>,
  67 L<RSA_print(3)|RSA_print(3)>
  68
  69 =cut