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