1=pod
2
3=head1 NAME
4
5DH_get0_pqg, DH_set0_pqg, DH_get0_key, DH_set0_key,
6DH_get0_p, DH_get0_q, DH_get0_g,
7DH_get0_priv_key, DH_get0_pub_key,
8DH_clear_flags, DH_test_flags, DH_set_flags, DH_get0_engine,
9DH_get_length, DH_set_length - Routines for getting and setting data in a DH object
10
11=head1 SYNOPSIS
12
13 #include <openssl/dh.h>
14
15The following functions have been deprecated since OpenSSL 3.0, and can be
16hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
17see L<openssl_user_macros(7)>:
18
19 void DH_get0_pqg(const DH *dh,
20                  const BIGNUM **p, const BIGNUM **q, const BIGNUM **g);
21 int DH_set0_pqg(DH *dh, BIGNUM *p, BIGNUM *q, BIGNUM *g);
22 void DH_get0_key(const DH *dh,
23                  const BIGNUM **pub_key, const BIGNUM **priv_key);
24 int DH_set0_key(DH *dh, BIGNUM *pub_key, BIGNUM *priv_key);
25 const BIGNUM *DH_get0_p(const DH *dh);
26 const BIGNUM *DH_get0_q(const DH *dh);
27 const BIGNUM *DH_get0_g(const DH *dh);
28 const BIGNUM *DH_get0_priv_key(const DH *dh);
29 const BIGNUM *DH_get0_pub_key(const DH *dh);
30 void DH_clear_flags(DH *dh, int flags);
31 int DH_test_flags(const DH *dh, int flags);
32 void DH_set_flags(DH *dh, int flags);
33
34 long DH_get_length(const DH *dh);
35 int DH_set_length(DH *dh, long length);
36
37 ENGINE *DH_get0_engine(DH *d);
38
39=head1 DESCRIPTION
40
41All of the functions described on this page are deprecated.
42Applications should instead use L<EVP_PKEY_get_bn_param(3)> for any methods that
43return a B<BIGNUM>. Refer to L<EVP_PKEY-DH(7)> for more information.
44
45A DH object contains the parameters I<p>, I<q> and I<g>. Note that the I<q>
46parameter is optional. It also contains a public key (I<pub_key>) and
47(optionally) a private key (I<priv_key>).
48
49The I<p>, I<q> and I<g> parameters can be obtained by calling DH_get0_pqg().
50If the parameters have not yet been set then I<*p>, I<*q> and I<*g> will be set
51to NULL. Otherwise they are set to pointers to their respective values. These
52point directly to the internal representations of the values and therefore
53should not be freed directly.
54Any of the out parameters I<p>, I<q>, and I<g> can be NULL, in which case no
55value will be returned for that parameter.
56
57The I<p>, I<q> and I<g> values can be set by calling DH_set0_pqg() and passing
58the new values for I<p>, I<q> and I<g> as parameters to the function. Calling
59this function transfers the memory management of the values to the DH object,
60and therefore the values that have been passed in should not be freed directly
61after this function has been called. The I<q> parameter may be NULL.
62DH_set0_pqg() also checks if the parameters associated with I<p> and I<g> and
63optionally I<q> are associated with known safe prime groups. If it is a safe
64prime group then the value of I<q> will be set to q = (p - 1) / 2 if I<q> is
65NULL. The optional length parameter will be set to BN_num_bits(I<q>) if I<q>
66is not NULL.
67
68To get the public and private key values use the DH_get0_key() function. A
69pointer to the public key will be stored in I<*pub_key>, and a pointer to the
70private key will be stored in I<*priv_key>. Either may be NULL if they have not
71been set yet, although if the private key has been set then the public key must
72be. The values point to the internal representation of the public key and
73private key values. This memory should not be freed directly.
74Any of the out parameters I<pub_key> and I<priv_key> can be NULL, in which case
75no value will be returned for that parameter.
76
77The public and private key values can be set using DH_set0_key(). Either
78parameter may be NULL, which means the corresponding DH field is left
79untouched. As with DH_set0_pqg() this function transfers the memory management
80of the key values to the DH object, and therefore they should not be freed
81directly after this function has been called.
82
83Any of the values I<p>, I<q>, I<g>, I<priv_key>, and I<pub_key> can also be
84retrieved separately by the corresponding function DH_get0_p(), DH_get0_q(),
85DH_get0_g(), DH_get0_priv_key(), and DH_get0_pub_key(), respectively.
86
87DH_set_flags() sets the flags in the I<flags> parameter on the DH object.
88Multiple flags can be passed in one go (bitwise ORed together). Any flags that
89are already set are left set. DH_test_flags() tests to see whether the flags
90passed in the I<flags> parameter are currently set in the DH object. Multiple
91flags can be tested in one go. All flags that are currently set are returned, or
92zero if none of the flags are set. DH_clear_flags() clears the specified flags
93within the DH object.
94
95DH_get0_engine() returns a handle to the ENGINE that has been set for this DH
96object, or NULL if no such ENGINE has been set. This function is deprecated. All
97engines should be replaced by providers.
98
99The DH_get_length() and DH_set_length() functions get and set the optional
100length parameter associated with this DH object. If the length is nonzero then
101it is used, otherwise it is ignored. The I<length> parameter indicates the
102length of the secret exponent (private key) in bits. For safe prime groups the optional length parameter I<length> can be
103set to a value greater or equal to 2 * maximum_target_security_strength(BN_num_bits(I<p>))
104as listed in SP800-56Ar3 Table(s) 25 & 26.
105These functions are deprecated and should be replaced with
106EVP_PKEY_CTX_set_params() and EVP_PKEY_get_int_param() using the parameter key
107B<OSSL_PKEY_PARAM_DH_PRIV_LEN> as described in L<EVP_PKEY-DH(7)>.
108
109=head1 NOTES
110
111Values retrieved with DH_get0_key() are owned by the DH object used
112in the call and may therefore I<not> be passed to DH_set0_key().  If
113needed, duplicate the received value using BN_dup() and pass the
114duplicate.  The same applies to DH_get0_pqg() and DH_set0_pqg().
115
116=head1 RETURN VALUES
117
118DH_set0_pqg() and DH_set0_key() return 1 on success or 0 on failure.
119
120DH_get0_p(), DH_get0_q(), DH_get0_g(), DH_get0_priv_key(), and DH_get0_pub_key()
121return the respective value, or NULL if it is unset.
122
123DH_test_flags() returns the current state of the flags in the DH object.
124
125DH_get0_engine() returns the ENGINE set for the DH object or NULL if no ENGINE
126has been set.
127
128DH_get_length() returns the length of the secret exponent (private key) in bits,
129or zero if no such length has been explicitly set.
130
131=head1 SEE ALSO
132
133L<DH_new(3)>, L<DH_new(3)>, L<DH_generate_parameters(3)>, L<DH_generate_key(3)>,
134L<DH_set_method(3)>, L<DH_size(3)>, L<DH_meth_new(3)>
135
136=head1 HISTORY
137
138The functions described here were added in OpenSSL 1.1.0.
139
140All of these functions were deprecated in OpenSSL 3.0.
141
142=head1 COPYRIGHT
143
144Copyright 2016-2023 The OpenSSL Project Authors. All Rights Reserved.
145
146Licensed under the Apache License 2.0 (the "License").  You may not use
147this file except in compliance with the License.  You can obtain a copy
148in the file LICENSE in the source distribution or at
149L<https://www.openssl.org/source/license.html>.
150
151=cut
152