xref: /openssl/doc/man3/EVP_MD_meth_new.pod (revision 7ed6de99) 
1=pod
2
3=head1 NAME
4
5EVP_MD_meth_new, EVP_MD_meth_dup, EVP_MD_meth_free,
6EVP_MD_meth_set_input_blocksize,
7EVP_MD_meth_set_result_size, EVP_MD_meth_set_app_datasize,
8EVP_MD_meth_set_flags, EVP_MD_meth_set_init, EVP_MD_meth_set_update,
9EVP_MD_meth_set_final, EVP_MD_meth_set_copy, EVP_MD_meth_set_cleanup,
10EVP_MD_meth_set_ctrl, EVP_MD_meth_get_input_blocksize,
11EVP_MD_meth_get_result_size, EVP_MD_meth_get_app_datasize,
12EVP_MD_meth_get_flags, EVP_MD_meth_get_init, EVP_MD_meth_get_update,
13EVP_MD_meth_get_final, EVP_MD_meth_get_copy, EVP_MD_meth_get_cleanup,
14EVP_MD_meth_get_ctrl
15- Routines to build up legacy EVP_MD methods
16
17=head1 SYNOPSIS
18
19 #include <openssl/evp.h>
20
21The following functions have been deprecated since OpenSSL 3.0, and can be
22hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
23see L<openssl_user_macros(7)>:
24
25 EVP_MD *EVP_MD_meth_new(int md_type, int pkey_type);
26 void EVP_MD_meth_free(EVP_MD *md);
27 EVP_MD *EVP_MD_meth_dup(const EVP_MD *md);
28
29 int EVP_MD_meth_set_input_blocksize(EVP_MD *md, int blocksize);
30 int EVP_MD_meth_set_result_size(EVP_MD *md, int resultsize);
31 int EVP_MD_meth_set_app_datasize(EVP_MD *md, int datasize);
32 int EVP_MD_meth_set_flags(EVP_MD *md, unsigned long flags);
33 int EVP_MD_meth_set_init(EVP_MD *md, int (*init)(EVP_MD_CTX *ctx));
34 int EVP_MD_meth_set_update(EVP_MD *md, int (*update)(EVP_MD_CTX *ctx,
35                                                      const void *data,
36                                                      size_t count));
37 int EVP_MD_meth_set_final(EVP_MD *md, int (*final)(EVP_MD_CTX *ctx,
38                                                    unsigned char *md));
39 int EVP_MD_meth_set_copy(EVP_MD *md, int (*copy)(EVP_MD_CTX *to,
40                                                  const EVP_MD_CTX *from));
41 int EVP_MD_meth_set_cleanup(EVP_MD *md, int (*cleanup)(EVP_MD_CTX *ctx));
42 int EVP_MD_meth_set_ctrl(EVP_MD *md, int (*ctrl)(EVP_MD_CTX *ctx, int cmd,
43                                                  int p1, void *p2));
44
45 int EVP_MD_meth_get_input_blocksize(const EVP_MD *md);
46 int EVP_MD_meth_get_result_size(const EVP_MD *md);
47 int EVP_MD_meth_get_app_datasize(const EVP_MD *md);
48 unsigned long EVP_MD_meth_get_flags(const EVP_MD *md);
49 int (*EVP_MD_meth_get_init(const EVP_MD *md))(EVP_MD_CTX *ctx);
50 int (*EVP_MD_meth_get_update(const EVP_MD *md))(EVP_MD_CTX *ctx,
51                                                 const void *data,
52                                                 size_t count);
53 int (*EVP_MD_meth_get_final(const EVP_MD *md))(EVP_MD_CTX *ctx,
54                                                unsigned char *md);
55 int (*EVP_MD_meth_get_copy(const EVP_MD *md))(EVP_MD_CTX *to,
56                                               const EVP_MD_CTX *from);
57 int (*EVP_MD_meth_get_cleanup(const EVP_MD *md))(EVP_MD_CTX *ctx);
58 int (*EVP_MD_meth_get_ctrl(const EVP_MD *md))(EVP_MD_CTX *ctx, int cmd,
59                                               int p1, void *p2);
60
61=head1 DESCRIPTION
62
63All of the functions described on this page are deprecated.
64Applications should instead use the OSSL_PROVIDER APIs.
65
66The B<EVP_MD> type is a structure for digest method implementation.
67It can also have associated public/private key signing and verifying
68routines.
69
70EVP_MD_meth_new() creates a new B<EVP_MD> structure.
71These B<EVP_MD> structures are reference counted.
72
73EVP_MD_meth_dup() creates a copy of B<md>.
74
75EVP_MD_meth_free() decrements the reference count for the B<EVP_MD> structure.
76If the reference count drops to 0 then the structure is freed.
77If the argument is NULL, nothing is done.
78
79EVP_MD_meth_set_input_blocksize() sets the internal input block size
80for the method B<md> to B<blocksize> bytes.
81
82EVP_MD_meth_set_result_size() sets the size of the result that the
83digest method in B<md> is expected to produce to B<resultsize> bytes.
84
85The digest method may have its own private data, which OpenSSL will
86allocate for it.  EVP_MD_meth_set_app_datasize() should be used to
87set the size for it to B<datasize>.
88
89EVP_MD_meth_set_flags() sets the flags to describe optional
90behaviours in the particular B<md>.  Several flags can be or'd
91together.  The available flags are:
92
93=over 4
94
95=item EVP_MD_FLAG_ONESHOT
96
97This digest method can only handle one block of input.
98
99=item EVP_MD_FLAG_XOF
100
101This digest method is an extensible-output function (XOF) and supports
102the B<EVP_MD_CTRL_XOF_LEN> control.
103
104=item EVP_MD_FLAG_DIGALGID_NULL
105
106When setting up a DigestAlgorithmIdentifier, this flag will have the
107parameter set to NULL by default.  Use this for PKCS#1.  I<Note: if
108combined with EVP_MD_FLAG_DIGALGID_ABSENT, the latter will override.>
109
110=item EVP_MD_FLAG_DIGALGID_ABSENT
111
112When setting up a DigestAlgorithmIdentifier, this flag will have the
113parameter be left absent by default.  I<Note: if combined with
114EVP_MD_FLAG_DIGALGID_NULL, the latter will be overridden.>
115
116=item EVP_MD_FLAG_DIGALGID_CUSTOM
117
118Custom DigestAlgorithmIdentifier handling via ctrl, with
119B<EVP_MD_FLAG_DIGALGID_ABSENT> as default.  I<Note: if combined with
120EVP_MD_FLAG_DIGALGID_NULL, the latter will be overridden.>
121Currently unused.
122
123=item EVP_MD_FLAG_FIPS
124
125This digest method is suitable for use in FIPS mode.
126Currently unused.
127
128=back
129
130EVP_MD_meth_set_init() sets the digest init function for B<md>.
131The digest init function is called by EVP_Digest(), EVP_DigestInit(),
132EVP_DigestInit_ex(), EVP_SignInit, EVP_SignInit_ex(), EVP_VerifyInit()
133and EVP_VerifyInit_ex().
134
135EVP_MD_meth_set_update() sets the digest update function for B<md>.
136The digest update function is called by EVP_Digest(), EVP_DigestUpdate() and
137EVP_SignUpdate().
138
139EVP_MD_meth_set_final() sets the digest final function for B<md>.
140The digest final function is called by EVP_Digest(), EVP_DigestFinal(),
141EVP_DigestFinal_ex(), EVP_SignFinal() and EVP_VerifyFinal().
142
143EVP_MD_meth_set_copy() sets the function for B<md> to do extra
144computations after the method's private data structure has been copied
145from one B<EVP_MD_CTX> to another.  If all that's needed is to copy
146the data, there is no need for this copy function.
147Note that the copy function is passed two B<EVP_MD_CTX *>, the private
148data structure is then available with EVP_MD_CTX_get0_md_data().
149This copy function is called by EVP_MD_CTX_copy() and
150EVP_MD_CTX_copy_ex().
151
152EVP_MD_meth_set_cleanup() sets the function for B<md> to do extra
153cleanup before the method's private data structure is cleaned out and
154freed.
155Note that the cleanup function is passed a B<EVP_MD_CTX *>, the
156private data structure is then available with EVP_MD_CTX_get0_md_data().
157This cleanup function is called by EVP_MD_CTX_reset() and
158EVP_MD_CTX_free().
159
160EVP_MD_meth_set_ctrl() sets the control function for B<md>.
161See L<EVP_MD_CTX_ctrl(3)> for the available controls.
162
163EVP_MD_meth_get_input_blocksize(), EVP_MD_meth_get_result_size(),
164EVP_MD_meth_get_app_datasize(), EVP_MD_meth_get_flags(),
165EVP_MD_meth_get_init(), EVP_MD_meth_get_update(),
166EVP_MD_meth_get_final(), EVP_MD_meth_get_copy(),
167EVP_MD_meth_get_cleanup() and EVP_MD_meth_get_ctrl() are all used
168to retrieve the method data given with the EVP_MD_meth_set_*()
169functions above.
170
171=head1 RETURN VALUES
172
173EVP_MD_meth_new() and EVP_MD_meth_dup() return a pointer to a newly
174created B<EVP_MD>, or NULL on failure.
175All EVP_MD_meth_set_*() functions return 1.
176EVP_MD_get_input_blocksize(), EVP_MD_meth_get_result_size(),
177EVP_MD_meth_get_app_datasize() and EVP_MD_meth_get_flags() return the
178indicated sizes or flags.
179All other EVP_CIPHER_meth_get_*() functions return pointers to their
180respective B<md> function.
181
182=head1 SEE ALSO
183
184L<EVP_DigestInit(3)>, L<EVP_SignInit(3)>, L<EVP_VerifyInit(3)>
185
186=head1 HISTORY
187
188All of these functions were deprecated in OpenSSL 3.0.
189
190The B<EVP_MD> structure was openly available in OpenSSL before version
1911.1.
192The functions described here were added in OpenSSL 1.1.
193The B<EVP_MD> structure created with these functions became reference
194counted in OpenSSL 3.0.
195
196=head1 COPYRIGHT
197
198Copyright 2015-2024 The OpenSSL Project Authors. All Rights Reserved.
199
200Licensed under the Apache License 2.0 (the "License").  You may not use
201this file except in compliance with the License.  You can obtain a copy
202in the file LICENSE in the source distribution or at
203L<https://www.openssl.org/source/license.html>.
204
205=cut
206