EVP_MD_METH_NEW(3SSL)

📦

version 3.5.7 · 11 versions

💜 EVP_MD_METH_NEW — the `3SSL` era icon ✨

okay so bestie, this is the manual page for EVP_MD_METH_NEW(3SSL) — an OpenSSL page, section 3SSL, and it is entirely about the legacy way of building your own EVP_MD digest methods. she's giving "vintage but we still need to know her" energy. 💅

🎀 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 — the routines to build up legacy EVP_MD methods. yes, that's the whole squad. 🫶

🌈 SYNOPSIS 🌈

#include <openssl/evp.h>

⚠️ heads up bestie — 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). so like, she's still here but she's on notice. 💀

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 💖

okay so first thing, before we get into the fun stuff: all of the functions described on this page are deprecated. not me being dramatic, that's literally what it says. applications should instead use the OSSL_PROVIDER APIs. that's the glow-up, bestie. ✨

The EVP_MD type is a structure for digest method implementation. it can also have associated public/private key signing and verifying routines. versatile queen. 👑

EVP_MD_meth_new() — creates a new EVP_MD structure. and get this, these EVP_MD structures are reference counted. iconic behaviour tbh.
EVP_MD_meth_dup() — creates a copy of md. twin energy. 🫶
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. and if the argument is NULL, nothing is done — she just shrugs and moves on. 💅
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 function is the one you use to set the size for it to datasize.
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:

🦋 the flags, one by one 🦋

EVP_MD_FLAG_ONESHOT — this digest method can only handle one block of input. one and done, no cap.
EVP_MD_FLAG_XOF — this digest method is an extensible-output function (XOF) and supports the EVP_MD_CTRL_XOF_LEN control. she keeps going and going, main character energy. ✨
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. also 🙈

🌸 the function setters, aka who calls whom 🌸

EVP_MD_meth_set_init() — sets the digest init function for md. this digest init function is called by EVP_Digest(), EVP_DigestInit(), EVP_DigestInit_ex(), EVP_SignInit, EVP_SignInit_ex(), EVP_VerifyInit() and EVP_VerifyInit_ex(). she gets around, and honestly? respect. 💅
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 *, and 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 an EVP_MD_CTX *, and 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(). self-care routine fr. 🧚
EVP_MD_meth_set_ctrl() — sets the control function for md. see EVP_MD_CTX_ctrl(3) for the available controls.

and then 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. matching set. we love a coordinated moment. 💖

⭐ 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. (short king behaviour, always the same answer.)
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.

like, go read those next, bestie. iykyk. 🫶

🎀 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. glow-up confirmed. ✨

💜 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 page, bestie! 🦋 this one is from OpenSSL 3.5.7, dated 2026-06-09 — EVP_MD_METH_NEW(3SSL), legacy era, still slaying in the archive. mwah 💋👑

📦 where this page comes from

debian trixie: libssl-doc 3.5.7-1~deb13u2 · Apache-2.0
debian trixie: libssl-doc 3.5.7-1~deb13u3 · Apache-2.0
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on 2026-11-06: a language model's rewrite of the original, under its terms