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CMS_ADD1_SIGNER(3ossl) OpenSSL CMS_ADD1_SIGNER(3ossl)
NAME
CMS_add1_signer, CMS_SignerInfo_sign - add a signer to a
CMS_ContentInfo signed data structure
SYNOPSIS
#include <openssl/cms.h>
CMS_SignerInfo *CMS_add1_signer(CMS_ContentInfo *cms, X509 *signcert,
EVP_PKEY *pkey, const EVP_MD *md,
unsigned int flags);
int CMS_SignerInfo_sign(CMS_SignerInfo *si);
DESCRIPTION
CMS_add1_signer() adds a signer with certificate signcert and private
key pkey using message digest md to CMS_ContentInfo SignedData
structure cms.
The CMS_ContentInfo structure should be obtained from an initial call
to CMS_sign() with the flag CMS_PARTIAL set or in the case or re-
signing a valid CMS_ContentInfo SignedData structure.
If the md parameter is NULL then the default digest for the public key
algorithm will be used.
Unless the CMS_REUSE_DIGEST flag is set the returned CMS_ContentInfo
structure is not complete and must be finalized either by streaming (if
applicable) or a call to CMS_final().
The CMS_SignerInfo_sign() function will explicitly sign a
CMS_SignerInfo structure, its main use is when CMS_REUSE_DIGEST and
CMS_PARTIAL flags are both set.
NOTES
The main purpose of CMS_add1_signer() is to provide finer control over
a CMS signed data structure where the simpler CMS_sign() function
defaults are not appropriate. For example if multiple signers or non
default digest algorithms are needed. New attributes can also be added
using the returned CMS_SignerInfo structure and the CMS attribute
utility functions or the CMS signed receipt request functions.
Any of the following flags (ored together) can be passed in the flags
parameter.
If CMS_REUSE_DIGEST is set then an attempt is made to copy the content
digest value from the CMS_ContentInfo structure: to add a signer to an
existing structure. An error occurs if a matching digest value cannot
be found to copy. The returned CMS_ContentInfo structure will be valid
and finalized when this flag is set.
If CMS_PARTIAL is set in addition to CMS_REUSE_DIGEST then the
CMS_SignerInfo structure will not be finalized so additional attributes
can be added. In this case an explicit call to CMS_SignerInfo_sign() is
needed to finalize it.
If CMS_NOCERTS is set the signer's certificate will not be included in
of ciphers in an SMIMECapabilities attribute. If CMS_NOATTR is set then
no signedAttributes will be used. If CMS_NOSMIMECAP is set then just
the SMIMECapabilities are omitted.
OpenSSL will by default identify signing certificates using issuer name
and serial number. If CMS_USE_KEYID is set it will use the subject key
identifier value instead. An error occurs if the signing certificate
does not have a subject key identifier extension.
If present the SMIMECapabilities attribute indicates support for the
following algorithms in preference order: 256 bit AES, Gost R3411-94,
Gost 28147-89, 192 bit AES, 128 bit AES, triple DES, 128 bit RC2, 64
bit RC2, DES and 40 bit RC2. If any of these algorithms is not
available then it will not be included: for example the GOST algorithms
will not be included if the GOST ENGINE is not loaded.
CMS_add1_signer() returns an internal pointer to the CMS_SignerInfo
structure just added, this can be used to set additional attributes
before it is finalized.
RETURN VALUES
CMS_add1_signer() returns an internal pointer to the CMS_SignerInfo
structure just added or NULL if an error occurs.
SEE ALSO
ERR_get_error(3), CMS_sign(3), CMS_final(3),
COPYRIGHT
Copyright 2014-2016 The OpenSSL Project Authors. All Rights Reserved.
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>.
3.0.11 2023-09-19 CMS_ADD1_SIGNER(3ossl)