.\" $OpenBSD: EVP_MD_meth_new.3,v 1.5 2023/09/12 16:26:30 schwarze Exp $ .\" selective merge up to: .\" OpenSSL man3/EVP_MD_meth_new 0388d212 Dec 14 12:47:07 2018 -0800 .\" .\" This file is a derived work. .\" The changes are covered by the following Copyright and license: .\" .\" Copyright (c) 2023 Ingo Schwarze .\" .\" Permission to use, copy, modify, and distribute this software for any .\" purpose with or without fee is hereby granted, provided that the above .\" copyright notice and this permission notice appear in all copies. .\" .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS. 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IN NO EVENT SHALL THE OpenSSL PROJECT OR .\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED .\" OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd $Mdocdate: September 12 2023 $ .Dt EVP_MD_METH_NEW 3 .Os .Sh NAME .Nm EVP_MD_meth_dup , .Nm EVP_MD_meth_new , .Nm EVP_MD_meth_free , .Nm EVP_MD_meth_set_input_blocksize , .Nm EVP_MD_meth_set_result_size , .Nm EVP_MD_meth_set_app_datasize , .Nm EVP_MD_meth_set_flags , .Nm EVP_MD_meth_set_init , .Nm EVP_MD_meth_set_update , .Nm EVP_MD_meth_set_final , .Nm EVP_MD_meth_set_copy , .Nm EVP_MD_meth_set_cleanup , .Nm EVP_MD_meth_set_ctrl .Nd Routines to build up EVP_MD methods .Sh SYNOPSIS .In openssl/evp.h .Ft EVP_MD * .Fo EVP_MD_meth_new .Fa "int md_type" .Fa "int pkey_type" .Fc .Ft void .Fo EVP_MD_meth_free .Fa "EVP_MD *md" .Fc .Ft EVP_MD * .Fo EVP_MD_meth_dup .Fa "const EVP_MD *md" .Fc .Ft int .Fo EVP_MD_meth_set_input_blocksize .Fa "EVP_MD *md" .Fa "int blocksize" .Fc .Ft int .Fo EVP_MD_meth_set_result_size .Fa "EVP_MD *md" .Fa "int resultsize" .Fc .Ft int .Fo EVP_MD_meth_set_app_datasize .Fa "EVP_MD *md" .Fa "int datasize" .Fc .Ft int .Fo EVP_MD_meth_set_flags .Fa "EVP_MD *md" .Fa "unsigned long flags" .Fc .Ft int .Fo EVP_MD_meth_set_init .Fa "EVP_MD *md" .Fa "int (*init)(EVP_MD_CTX *ctx)" .Fc .Ft int .Fo EVP_MD_meth_set_update .Fa "EVP_MD *md" .Fa "int (*update)(EVP_MD_CTX *ctx, const void *data, size_t count)" .Fc .Ft int .Fo EVP_MD_meth_set_final .Fa "EVP_MD *md" .Fa "int (*final)(EVP_MD_CTX *ctx, unsigned char *md)" .Fc .Ft int .Fo EVP_MD_meth_set_copy .Fa "EVP_MD *md" .Fa "int (*copy)(EVP_MD_CTX *to, const EVP_MD_CTX *from)" .Fc .Ft int .Fo EVP_MD_meth_set_cleanup .Fa "EVP_MD *md" .Fa "int (*cleanup)(EVP_MD_CTX *ctx)" .Fc .Ft int .Fo EVP_MD_meth_set_ctrl .Fa "EVP_MD *md" .Fa "int (*control)(EVP_MD_CTX *ctx, int command, int p1, void *p2)" .Fc .Sh DESCRIPTION The .Vt EVP_MD type is a structure for digest method implementation. It can also have associated public/private key signing and verifying routines. .Pp .Fn EVP_MD_meth_new creates a new .Vt EVP_MD structure. .Pp .Fn EVP_MD_meth_dup creates a copy of .Fa md . .Pp .Fn EVP_MD_meth_free destroys a .Vt EVP_MD structure. .Pp .Fn EVP_MD_meth_set_input_blocksize sets the internal input block size for the method .Fa md to .Fa blocksize bytes. .Pp .Fn EVP_MD_meth_set_result_size sets the size of the result that the digest method in .Fa md is expected to produce to .Fa resultsize bytes. .Pp The digest method may have its own private data, which OpenSSL will allocate for it. .Fn EVP_MD_meth_set_app_datasize should be used to set the size for it to .Fa datasize . .Pp .Fn EVP_MD_meth_set_flags sets the flags to describe optional behaviours in the particular .Fa md . Several flags can be or'd together. The available flags are: .Bl -tag -width Ds .It Dv EVP_MD_FLAG_DIGALGID_NULL When setting up a .Vt DigestAlgorithmIdentifier with .Xr X509_ALGOR_set_md 3 , set the parameter type to .Dv V_ASN1_NULL and the parameter value to .Dv NULL . This is the default, which means that it takes effect for .Vt EVP_MD objects that do not have .Dv EVP_MD_FLAG_DIGALGID_ABSENT set. Use this for PKCS#1. .It Dv EVP_MD_FLAG_DIGALGID_ABSENT When setting up a .Vt DigestAlgorithmIdentifier with .Xr X509_ALGOR_set_md 3 , set the parameter type to .Dv V_ASN1_UNDEF and the parameter value to .Dv NULL . This is used by the .Vt EVP_MD objects documented in the manual page .Xr EVP_sha3_224 3 and by the objects returned from .Xr EVP_sha512 3 , .Xr EVP_sha512_256 3 , .Xr EVP_sha512_224 3 , .Xr EVP_sha384 3 , .Xr EVP_sha256 3 , .Xr EVP_sha224 3 , .Xr EVP_sha1 3 , and .Xr EVP_sm3 3 . .It Dv EVP_MD_FLAG_DIGALGID_CUSTOM This flag is reserved for user-defined .Vt EVP_MD objects supporting custom .Vt DigestAlgorithmIdentifier handling via .Xr EVP_MD_CTX_ctrl 3 , but actually, it is ignored by both LibreSSL and OpenSSL and such user-defined behaviour is not supported by the libraries. .It Dv EVP_MD_FLAG_FIPS Mark the digest method as suitable for FIPS mode. This flag is ignored by both LibreSSL and OpenSSL. .It Dv EVP_MD_FLAG_ONESHOT Intended to indicate that the digest method can only handle one block of input, but actually, this flag is ignored by both LibreSSL and OpenSSL. .El .Pp .Fn EVP_MD_meth_set_init sets the digest init function for .Fa md . The digest init function is called by .Xr EVP_Digest 3 , .Xr EVP_DigestInit 3 , .Xr EVP_DigestInit_ex 3 , EVP_SignInit, .Xr EVP_SignInit_ex 3 , .Xr EVP_VerifyInit 3 and .Xr EVP_VerifyInit_ex 3 . .Pp .Fn EVP_MD_meth_set_update sets the digest update function for .Fa md . The digest update function is called by .Xr EVP_Digest 3 , .Xr EVP_DigestUpdate 3 and .Xr EVP_SignUpdate 3 . .Pp .Fn EVP_MD_meth_set_final sets the digest final function for .Fa md . The digest final function is called by .Xr EVP_Digest 3 , .Xr EVP_DigestFinal 3 , .Xr EVP_DigestFinal_ex 3 , .Xr EVP_SignFinal 3 and .Xr EVP_VerifyFinal 3 . .Pp .Fn EVP_MD_meth_set_copy sets the function for .Fa md to do extra computations after the method's private data structure has been copied from one .Vt EVP_MD_CTX object to another. If all that's needed is to copy the data, there is no need for this copy function. The copy function is passed two .Vt EVP_MD_CTX objects, the private data structure is then available with .Xr EVP_MD_CTX_md_data 3 . This copy function is called by .Xr EVP_MD_CTX_copy 3 and .Xr EVP_MD_CTX_copy_ex 3 . .Pp .Fn EVP_MD_meth_set_cleanup sets the function for .Fa md to do extra cleanup before the method's private data structure is cleaned out and freed. The cleanup function is passed an .Vt EVP_MD_CTX object, the private data structure is then available with .Xr EVP_MD_CTX_md_data 3 . This cleanup function is called by .Xr EVP_MD_CTX_reset 3 and .Xr EVP_MD_CTX_free 3 . .Pp .Fn EVP_MD_meth_set_ctrl sets the .Fa control function for .Fa md . The .Fa control function supplied by the application program has to return 1 to indicate success, 0 to indicate failure, or \-1 if the .Fa command is not supported for this digest method. See .Xr EVP_MD_CTX_ctrl 3 for the available .Fa command arguments. .Sh RETURN VALUES .Fn EVP_MD_meth_new and .Fn EVP_MD_meth_dup return a pointer to a newly created .Vt EVP_MD , or NULL on failure. All .Fn EVP_MD_meth_set_* functions return 1. .Sh SEE ALSO .Xr EVP_DigestInit 3 , .Xr EVP_SignInit 3 , .Xr EVP_VerifyInit 3 .Sh HISTORY All these functions first appeared in OpenSSL 1.1.0 and have been available since .Ox 7.1 .