1=pod
2
3=head1 NAME
4
5EVP_MD_meth_dup,
6EVP_MD_meth_new, EVP_MD_meth_free, EVP_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 EVP_MD methods
16
17=head1 SYNOPSIS
18
19 #include <openssl/evp.h>
20
21 EVP_MD *EVP_MD_meth_new(int md_type, int pkey_type);
22 void EVP_MD_meth_free(EVP_MD *md);
23 EVP_MD *EVP_MD_meth_dup(const EVP_MD *md);
24
25 int EVP_MD_meth_set_input_blocksize(EVP_MD *md, int blocksize);
26 int EVP_MD_meth_set_result_size(EVP_MD *md, int resultsize);
27 int EVP_MD_meth_set_app_datasize(EVP_MD *md, int datasize);
28 int EVP_MD_meth_set_flags(EVP_MD *md, unsigned long flags);
29 int EVP_MD_meth_set_init(EVP_MD *md, int (*init)(EVP_MD_CTX *ctx));
30 int EVP_MD_meth_set_update(EVP_MD *md, int (*update)(EVP_MD_CTX *ctx,
31                                                      const void *data,
32                                                      size_t count));
33 int EVP_MD_meth_set_final(EVP_MD *md, int (*final)(EVP_MD_CTX *ctx,
34                                                    unsigned char *md));
35 int EVP_MD_meth_set_copy(EVP_MD *md, int (*copy)(EVP_MD_CTX *to,
36                                                  const EVP_MD_CTX *from));
37 int EVP_MD_meth_set_cleanup(EVP_MD *md, int (*cleanup)(EVP_MD_CTX *ctx));
38 int EVP_MD_meth_set_ctrl(EVP_MD *md, int (*ctrl)(EVP_MD_CTX *ctx, int cmd,
39                                                  int p1, void *p2));
40
41 int EVP_MD_meth_get_input_blocksize(const EVP_MD *md);
42 int EVP_MD_meth_get_result_size(const EVP_MD *md);
43 int EVP_MD_meth_get_app_datasize(const EVP_MD *md);
44 unsigned long EVP_MD_meth_get_flags(const EVP_MD *md);
45 int (*EVP_MD_meth_get_init(const EVP_MD *md))(EVP_MD_CTX *ctx);
46 int (*EVP_MD_meth_get_update(const EVP_MD *md))(EVP_MD_CTX *ctx,
47                                                 const void *data,
48                                                 size_t count);
49 int (*EVP_MD_meth_get_final(const EVP_MD *md))(EVP_MD_CTX *ctx,
50                                                unsigned char *md);
51 int (*EVP_MD_meth_get_copy(const EVP_MD *md))(EVP_MD_CTX *to,
52                                               const EVP_MD_CTX *from);
53 int (*EVP_MD_meth_get_cleanup(const EVP_MD *md))(EVP_MD_CTX *ctx);
54 int (*EVP_MD_meth_get_ctrl(const EVP_MD *md))(EVP_MD_CTX *ctx, int cmd,
55                                               int p1, void *p2);
56
57=head1 DESCRIPTION
58
59The B<EVP_MD> type is a structure for digest method implementation.
60It can also have associated public/private key signing and verifying
61routines.
62
63EVP_MD_meth_new() creates a new B<EVP_MD> structure.
64
65EVP_MD_meth_dup() creates a copy of B<md>.
66
67EVP_MD_meth_free() destroys a B<EVP_MD> structure.
68
69EVP_MD_meth_set_input_blocksize() sets the internal input block size
70for the method B<md> to B<blocksize> bytes.
71
72EVP_MD_meth_set_result_size() sets the size of the result that the
73digest method in B<md> is expected to produce to B<resultsize> bytes.
74
75The digest method may have its own private data, which OpenSSL will
76allocate for it.  EVP_MD_meth_set_app_datasize() should be used to
77set the size for it to B<datasize>.
78
79EVP_MD_meth_set_flags() sets the flags to describe optional
80behaviours in the particular B<md>.  Several flags can be or'd
81together.  The available flags are:
82
83=over 4
84
85=item EVP_MD_FLAG_ONESHOT
86
87This digest method can only handles one block of input.
88
89=item EVP_MD_FLAG_DIGALGID_NULL
90
91When setting up a DigestAlgorithmIdentifier, this flag will have the
92parameter set to NULL by default.  Use this for PKCS#1.  I<Note: if
93combined with EVP_MD_FLAG_DIGALGID_ABSENT, the latter will override.>
94
95=item EVP_MD_FLAG_DIGALGID_ABSENT
96
97When setting up a DigestAlgorithmIdentifier, this flag will have the
98parameter be left absent by default.  I<Note: if combined with
99EVP_MD_FLAG_DIGALGID_NULL, the latter will be overridden.>
100
101=item EVP_MD_FLAG_DIGALGID_CUSTOM
102
103Custom DigestAlgorithmIdentifier handling via ctrl, with
104B<EVP_MD_FLAG_DIGALGID_ABSENT> as default.  I<Note: if combined with
105EVP_MD_FLAG_DIGALGID_NULL, the latter will be overridden.>
106Currently unused.
107
108=back
109
110EVP_MD_meth_set_init() sets the digest init function for B<md>.
111The digest init function is called by EVP_DigestInit(),
112EVP_DigestInit_ex(), EVP_SignInit, EVP_SignInit_ex(), EVP_VerifyInit()
113and EVP_VerifyInit_ex().
114
115EVP_MD_meth_set_update() sets the digest update function for B<md>.
116The digest update function is called by EVP_DigestUpdate(),
117EVP_SignUpdate().
118
119EVP_MD_meth_set_final() sets the digest final function for B<md>.
120The digest final function is called by EVP_DigestFinal(),
121EVP_DigestFinal_ex(), EVP_SignFinal() and EVP_VerifyFinal().
122
123EVP_MD_meth_set_copy() sets the function for B<md> to do extra
124computations after the method's private data structure has been copied
125from one B<EVP_MD_CTX> to another.  If all that's needed is to copy
126the data, there is no need for this copy function.
127Note that the copy function is passed two B<EVP_MD_CTX *>, the private
128data structure is then available with EVP_MD_CTX_md_data().
129This copy function is called by EVP_MD_CTX_copy() and
130EVP_MD_CTX_copy_ex().
131
132EVP_MD_meth_set_cleanup() sets the function for B<md> to do extra
133cleanup before the method's private data structure is cleaned out and
134freed.
135Note that the cleanup function is passed a B<EVP_MD_CTX *>, the
136private data structure is then available with EVP_MD_CTX_md_data().
137This cleanup function is called by EVP_MD_CTX_reset() and
138EVP_MD_CTX_free().
139
140EVP_MD_meth_set_ctrl() sets the control function for B<md>.
141
142EVP_MD_meth_get_input_blocksize(), EVP_MD_meth_get_result_size(),
143EVP_MD_meth_get_app_datasize(), EVP_MD_meth_get_flags(),
144EVP_MD_meth_get_init(), EVP_MD_meth_get_update(),
145EVP_MD_meth_get_final(), EVP_MD_meth_get_copy(),
146EVP_MD_meth_get_cleanup() and EVP_MD_meth_get_ctrl() are all used
147to retrieve the method data given with the EVP_MD_meth_set_*()
148functions above.
149
150=head1 RETURN VALUES
151
152EVP_MD_meth_new() and EVP_MD_meth_dup() return a pointer to a newly
153created B<EVP_MD>, or NULL on failure.
154All EVP_MD_meth_set_*() functions return 1.
155EVP_MD_get_input_blocksize(), EVP_MD_meth_get_result_size(),
156EVP_MD_meth_get_app_datasize() and EVP_MD_meth_get_flags() return the
157indicated sizes or flags.
158All other EVP_CIPHER_meth_get_*() functions return pointers to their
159respective B<md> function.
160
161=head1 SEE ALSO
162
163L<EVP_DigestInit(3)>, L<EVP_SignInit(3)>, L<EVP_VerifyInit(3)>
164
165=head1 HISTORY
166
167The B<EVP_MD> structure was openly available in OpenSSL before version
1681.1.  The functions described here were added in OpenSSL 1.1.
169
170=head1 COPYRIGHT
171
172Copyright 2015-2017 The OpenSSL Project Authors. All Rights Reserved.
173
174Licensed under the OpenSSL license (the "License").  You may not use
175this file except in compliance with the License.  You can obtain a copy
176in the file LICENSE in the source distribution or at
177L<https://www.openssl.org/source/license.html>.
178
179=cut
180