EVP_MD_METH_NEW(3ossl)

📦

version 3.5.9 · 8 versions

3.5.9 · fedora 43, fedora 44 (latest)
3.5.9 · centos-stream 9
3.5.9 · centos-stream 10
3.5.9 · alpine 3.22
3.5.9 · alpine 3.23, alpine 3.24
3.5.8 · fedora 43
3.5.1 · fedora 43
3.5.5 · fedora 44

💅 EVP_MD_METH_NEW — the legacy digest-method builder page, bestie

okay so welcome to EVP_MD_METH_NEW(3ossl), the OpenSSL manual page all about building up legacy EVP_MD methods 🎀. Yes it's giving deprecated. Yes we still gotta know it. Let's go 🌸

✨ NAME ✨

EVP_MD_meth_new, EVP_MD_meth_dup, EVP_MD_meth_free, EVP_MD_meth_set_input_blocksize, EVP_MD_meth_set_result_size, EVP_MD_meth_set_app_datasize, EVP_MD_meth_set_flags, EVP_MD_meth_set_init, EVP_MD_meth_set_update, EVP_MD_meth_set_final, EVP_MD_meth_set_copy, EVP_MD_meth_set_cleanup, EVP_MD_meth_set_ctrl, EVP_MD_meth_get_input_blocksize, EVP_MD_meth_get_result_size, EVP_MD_meth_get_app_datasize, EVP_MD_meth_get_flags, EVP_MD_meth_get_init, EVP_MD_meth_get_update, EVP_MD_meth_get_final, EVP_MD_meth_get_copy, EVP_MD_meth_get_cleanup, EVP_MD_meth_get_ctrl — Routines to build up legacy EVP_MD methods 🦋

🌈 SYNOPSIS 🌈

#include <openssl/evp.h>

Lowkey important heads up: the following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):

EVP_MD *EVP_MD_meth_new(int md_type, int pkey_type);
void EVP_MD_meth_free(EVP_MD *md);
EVP_MD *EVP_MD_meth_dup(const EVP_MD *md);

int EVP_MD_meth_set_input_blocksize(EVP_MD *md, int blocksize);
int EVP_MD_meth_set_result_size(EVP_MD *md, int resultsize);
int EVP_MD_meth_set_app_datasize(EVP_MD *md, int datasize);
int EVP_MD_meth_set_flags(EVP_MD *md, unsigned long flags);
int EVP_MD_meth_set_init(EVP_MD *md, int (*init)(EVP_MD_CTX *ctx));
int EVP_MD_meth_set_update(EVP_MD *md, int (*update)(EVP_MD_CTX *ctx,
                                                     const void *data,
                                                     size_t count));
int EVP_MD_meth_set_final(EVP_MD *md, int (*final)(EVP_MD_CTX *ctx,
                                                   unsigned char *md));
int EVP_MD_meth_set_copy(EVP_MD *md, int (*copy)(EVP_MD_CTX *to,
                                                 const EVP_MD_CTX *from));
int EVP_MD_meth_set_cleanup(EVP_MD *md, int (*cleanup)(EVP_MD_CTX *ctx));
int EVP_MD_meth_set_ctrl(EVP_MD *md, int (*ctrl)(EVP_MD_CTX *ctx, int cmd,
                                                 int p1, void *p2));

int EVP_MD_meth_get_input_blocksize(const EVP_MD *md);
int EVP_MD_meth_get_result_size(const EVP_MD *md);
int EVP_MD_meth_get_app_datasize(const EVP_MD *md);
unsigned long EVP_MD_meth_get_flags(const EVP_MD *md);
int (*EVP_MD_meth_get_init(const EVP_MD *md))(EVP_MD_CTX *ctx);
int (*EVP_MD_meth_get_update(const EVP_MD *md))(EVP_MD_CTX *ctx,
                                                const void *data,
                                                size_t count);
int (*EVP_MD_meth_get_final(const EVP_MD *md))(EVP_MD_CTX *ctx,
                                               unsigned char *md);
int (*EVP_MD_meth_get_copy(const EVP_MD *md))(EVP_MD_CTX *to,
                                              const EVP_MD_CTX *from);
int (*EVP_MD_meth_get_cleanup(const EVP_MD *md))(EVP_MD_CTX *ctx);
int (*EVP_MD_meth_get_ctrl(const EVP_MD *md))(EVP_MD_CTX *ctx, int cmd,
                                              int p1, void *p2);

🫶 DESCRIPTION 🫶

⚠️ All of the functions described on this page are deprecated. Applications should instead use the OSSL_PROVIDER APIs. no cap, this is the old way 💀

So the EVP_MD type is a structure for digest method implementation. It can also have associated public/private key signing and verifying routines. multi-talented, honestly 👑

EVP_MD_meth_new() — creates a new EVP_MD structure. These EVP_MD structures are reference counted. ✨
EVP_MD_meth_dup() — creates a copy of md. 🦋
EVP_MD_meth_free() — decrements the reference count for the EVP_MD structure. If the reference count drops to 0 then the structure is freed. If the argument is NULL, nothing is done. (respectful of your time fr) 💅

🌸 the setters, one by one 🌸

EVP_MD_meth_set_input_blocksize() — sets the internal input block size for the method md to blocksize bytes.
EVP_MD_meth_set_result_size() — sets the size of the result that the digest method in md is expected to produce to resultsize bytes.
EVP_MD_meth_set_app_datasize() — the digest method may have its own private data, which OpenSSL will allocate for it. This one should be used to set the size for it to datasize. 🎀

🦋 `EVP_MD_meth_set_flags()` and the flag lore 🦋

EVP_MD_meth_set_flags() sets the flags to describe optional behaviours in the particular md. Several flags can be or'd together. The available flags are:

EVP_MD_FLAG_ONESHOT — This digest method can only handle one block of input.
EVP_MD_FLAG_XOF — This digest method is an extensible-output function (XOF) and supports the EVP_MD_CTRL_XOF_LEN control.
EVP_MD_FLAG_DIGALGID_NULL — When setting up a DigestAlgorithmIdentifier, this flag will have the parameter set to NULL by default. Use this for PKCS#1. Note: if combined with EVP_MD_FLAG_DIGALGID_ABSENT, the latter will override.
EVP_MD_FLAG_DIGALGID_ABSENT — When setting up a DigestAlgorithmIdentifier, this flag will have the parameter be left absent by default. Note: if combined with EVP_MD_FLAG_DIGALGID_NULL, the latter will be overridden.
EVP_MD_FLAG_DIGALGID_CUSTOM — Custom DigestAlgorithmIdentifier handling via ctrl, with EVP_MD_FLAG_DIGALGID_ABSENT as default. Note: if combined with EVP_MD_FLAG_DIGALGID_NULL, the latter will be overridden. Currently unused.
EVP_MD_FLAG_FIPS — This digest method is suitable for use in FIPS mode. Currently unused.

💜 the rest of the setters 💜

EVP_MD_meth_set_init() — sets the digest init function for md. The digest init function is called by EVP_Digest(), EVP_DigestInit(), EVP_DigestInit_ex(), EVP_SignInit, EVP_SignInit_ex(), EVP_VerifyInit() and EVP_VerifyInit_ex().
EVP_MD_meth_set_update() — sets the digest update function for md. The digest update function is called by EVP_Digest(), EVP_DigestUpdate() and EVP_SignUpdate().
EVP_MD_meth_set_final() — sets the digest final function for md. The digest final function is called by EVP_Digest(), EVP_DigestFinal(), EVP_DigestFinal_ex(), EVP_SignFinal() and EVP_VerifyFinal().
EVP_MD_meth_set_copy() — sets the function for md to do extra computations after the method's private data structure has been copied from one EVP_MD_CTX to another. If all that's needed is to copy the data, there is no need for this copy function. Note that the copy function is passed two EVP_MD_CTX *, the private data structure is then available with EVP_MD_CTX_get0_md_data(). This copy function is called by EVP_MD_CTX_copy() and EVP_MD_CTX_copy_ex().
EVP_MD_meth_set_cleanup() — sets the function for md to do extra cleanup before the method's private data structure is cleaned out and freed. Note that the cleanup function is passed a EVP_MD_CTX *, the private data structure is then available with EVP_MD_CTX_get0_md_data(). This cleanup function is called by EVP_MD_CTX_reset() and EVP_MD_CTX_free().
EVP_MD_meth_set_ctrl() — sets the control function for md. See EVP_MD_CTX_ctrl(3) for the available controls.

🎀 and the getters 🎀

EVP_MD_meth_get_input_blocksize(), EVP_MD_meth_get_result_size(), EVP_MD_meth_get_app_datasize(), EVP_MD_meth_get_flags(), EVP_MD_meth_get_init(), EVP_MD_meth_get_update(), EVP_MD_meth_get_final(), EVP_MD_meth_get_copy(), EVP_MD_meth_get_cleanup() and EVP_MD_meth_get_ctrl() are all used to retrieve the method data given with the EVP_MD_meth_set_*() functions above. they're the lil read-back girlies 💖

🔥 RETURN VALUES 🔥

EVP_MD_meth_new() and EVP_MD_meth_dup() return a pointer to a newly created EVP_MD, or NULL on failure. 😭
All EVP_MD_meth_set_*() functions return 1. iconic, consistent, slay ✨
EVP_MD_get_input_blocksize(), EVP_MD_meth_get_result_size(), EVP_MD_meth_get_app_datasize() and EVP_MD_meth_get_flags() return the indicated sizes or flags.
All other EVP_CIPHER_meth_get_*() functions return pointers to their respective md function.

📜 HISTORY 📜

All of these functions were deprecated in OpenSSL 3.0.
The EVP_MD structure was openly available in OpenSSL before version 1.1.
The functions described here were added in OpenSSL 1.1.
The EVP_MD structure created with these functions became reference counted in OpenSSL 3.0.

💖 COPYRIGHT 💖

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

and that's the whole page bestie, you ate 🫶 this was 3.5.9 of the OpenSSL manual, dated 2026-09-29, and it lives at EVP_MD_METH_NEW(3ossl) — go build something cute (with the provider APIs tho, fr fr) 💅✨

📦 where this page comes from

fedora 43: openssl-devel 1:3.5.9-1.fc43 · Apache-2.0
fedora 43: openssl-devel 1:3.5.9-1.fc43 · Apache-2.0
fedora 44: openssl-devel 1:3.5.9-1.fc44 · Apache-2.0
fedora 44: openssl-devel 1:3.5.9-1.fc44 · Apache-2.0
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on 2026-10-14: a language model's rewrite of the original, under its terms