X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=blobdiff_plain;f=doc%2Fcrypto%2Fdh.pod;h=c3ccd062078304ad6f237417dae48047bfe0c4f8;hp=6f0f73f0a118613b6aa78828f6eb67f386c6149d;hb=e640fa02005422c8783b7a452329e8a5059be0b5;hpb=223fc8654a790c204536cd7c61520154418915b8

diff --git a/doc/crypto/dh.pod b/doc/crypto/dh.pod
index 6f0f73f0a1..c3ccd06207 100644
--- a/doc/crypto/dh.pod
+++ b/doc/crypto/dh.pod
@@ -7,41 +7,42 @@ dh - Diffie-Hellman key agreement
 =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.
@@ -56,10 +57,22 @@ The B<DH> structure consists of several BIGNUM components.
         };
  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), RSA_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