[thirdparty/openssl.git] / doc / man3 / CMS_add1_signer.pod

=pod

=head1 NAME

CMS_add1_signer, CMS_SignerInfo_sign - add a signer to a CMS_ContentInfo signed data structure

=head1 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);

=head1 DESCRIPTION

CMS_add1_signer() adds a signer with certificate B<signcert> and private
key B<pkey> using message digest B<md> to CMS_ContentInfo SignedData
structure B<cms>.

The CMS_ContentInfo structure should be obtained from an initial call to
CMS_sign() with the flag B<CMS_PARTIAL> set or in the case or re-signing a
valid CMS_ContentInfo SignedData structure.

If the B<md> parameter is B<NULL> then the default digest for the public
key algorithm will be used.

Unless the B<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 B<CMS_REUSE_DIGEST> and B<CMS_PARTIAL> flags
are both set.

=head1 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 B<flags>
parameter.

If B<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 B<CMS_PARTIAL> is set in addition to B<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 B<CMS_NOCERTS> is set the signer's certificate will not be included in the
CMS_ContentInfo structure, the signer's certificate must still be supplied in
the B<signcert> parameter though. This can reduce the size of the signature if
the signers certificate can be obtained by other means: for example a
previously signed message.

The SignedData structure includes several CMS signedAttributes including the
signing time, the CMS content type and the supported list of ciphers in an
SMIMECapabilities attribute. If B<CMS_NOATTR> is set then no signedAttributes
will be used. If B<CMS_NOSMIMECAP> is set then just the SMIMECapabilities are
omitted.

OpenSSL will by default identify signing certificates using issuer name
and serial number. If B<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.

=head1 RETURN VALUES

CMS_add1_signer() returns an internal pointer to the CMS_SignerInfo
structure just added or NULL if an error occurs.

=head1 SEE ALSO

L<ERR_get_error(3)>, L<CMS_sign(3)>,
L<CMS_final(3)>,

=head1 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
L<https://www.openssl.org/source/license.html>.

=cut
Commit	Line	Data
e33ffaca DSH	1	=pod
	2
	3	=head1 NAME
	4
bb9ad09e	5	CMS_add1_signer, CMS_SignerInfo_sign - add a signer to a CMS_ContentInfo signed data structure
e33ffaca DSH	6
	7	=head1 SYNOPSIS
	8
	9	#include <openssl/cms.h>
	10
e9b77246 BB	11	CMS_SignerInfo CMS_add1_signer(CMS_ContentInfo cms, X509 *signcert,
	12	EVP_PKEY pkey, const EVP_MD md,
	13	unsigned int flags);
e33ffaca	14
38d3a738	15	int CMS_SignerInfo_sign(CMS_SignerInfo *si);
e33ffaca	16
e33ffaca DSH	17	=head1 DESCRIPTION
e33ffaca DSH	18
5886354d	19	CMS_add1_signer() adds a signer with certificate B<signcert> and private
38d3a738	20	key B<pkey> using message digest B<md> to CMS_ContentInfo SignedData
e33ffaca DSH	21	structure B<cms>.
	22
	23	The CMS_ContentInfo structure should be obtained from an initial call to
	24	CMS_sign() with the flag B<CMS_PARTIAL> set or in the case or re-signing a
38d3a738	25	valid CMS_ContentInfo SignedData structure.
e33ffaca DSH	26
	27	If the B<md> parameter is B<NULL> then the default digest for the public
	28	key algorithm will be used.
	29
	30	Unless the B<CMS_REUSE_DIGEST> flag is set the returned CMS_ContentInfo
	31	structure is not complete and must be finalized either by streaming (if
	32	applicable) or a call to CMS_final().
	33
	34	The CMS_SignerInfo_sign() function will explicitly sign a CMS_SignerInfo
	35	structure, its main use is when B<CMS_REUSE_DIGEST> and B<CMS_PARTIAL> flags
	36	are both set.
	37
	38	=head1 NOTES
	39
5886354d	40	The main purpose of CMS_add1_signer() is to provide finer control
86173db8 DSH	41	over a CMS signed data structure where the simpler CMS_sign() function defaults
86173db8 DSH	42	are not appropriate. For example if multiple signers or non default digest
e33ffaca	43	algorithms are needed. New attributes can also be added using the returned
c420fab5	44	CMS_SignerInfo structure and the CMS attribute utility functions or the
6469a1fd	45	CMS signed receipt request functions.
e33ffaca DSH	46
	47	Any of the following flags (ored together) can be passed in the B<flags>
	48	parameter.
	49
	50	If B<CMS_REUSE_DIGEST> is set then an attempt is made to copy the content
c420fab5	51	digest value from the CMS_ContentInfo structure: to add a signer to an existing
e33ffaca DSH	52	structure. An error occurs if a matching digest value cannot be found to copy.
	53	The returned CMS_ContentInfo structure will be valid and finalized when this
	54	flag is set.
	55
1bc74519	56	If B<CMS_PARTIAL> is set in addition to B<CMS_REUSE_DIGEST> then the
86173db8 DSH	57	CMS_SignerInfo structure will not be finalized so additional attributes
86173db8 DSH	58	can be added. In this case an explicit call to CMS_SignerInfo_sign() is
e33ffaca DSH	59	needed to finalize it.
	60
	61	If B<CMS_NOCERTS> is set the signer's certificate will not be included in the
	62	CMS_ContentInfo structure, the signer's certificate must still be supplied in
	63	the B<signcert> parameter though. This can reduce the size of the signature if
	64	the signers certificate can be obtained by other means: for example a
	65	previously signed message.
	66
38d3a738	67	The SignedData structure includes several CMS signedAttributes including the
e33ffaca DSH	68	signing time, the CMS content type and the supported list of ciphers in an
	69	SMIMECapabilities attribute. If B<CMS_NOATTR> is set then no signedAttributes
	70	will be used. If B<CMS_NOSMIMECAP> is set then just the SMIMECapabilities are
	71	omitted.
	72
	73	OpenSSL will by default identify signing certificates using issuer name
	74	and serial number. If B<CMS_USE_KEYID> is set it will use the subject key
	75	identifier value instead. An error occurs if the signing certificate does not
	76	have a subject key identifier extension.
	77
	78	If present the SMIMECapabilities attribute indicates support for the following
86173db8 DSH	79	algorithms in preference order: 256 bit AES, Gost R3411-94, Gost 28147-89, 192
	80	bit AES, 128 bit AES, triple DES, 128 bit RC2, 64 bit RC2, DES and 40 bit RC2.
	81	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
	82	not loaded.
e33ffaca	83
5886354d	84	CMS_add1_signer() returns an internal pointer to the CMS_SignerInfo
1bc74519	85	structure just added, this can be used to set additional attributes
e33ffaca DSH	86	before it is finalized.
	87
	88	=head1 RETURN VALUES
	89
5886354d	90	CMS_add1_signer() returns an internal pointer to the CMS_SignerInfo
e33ffaca DSH	91	structure just added or NULL if an error occurs.
	92
	93	=head1 SEE ALSO
	94
9b86974e RS	95	L<ERR_get_error(3)>, L<CMS_sign(3)>,
9b86974e RS	96	L<CMS_final(3)>,
e33ffaca	97
e2f92610 RS	98	=head1 COPYRIGHT
	99
	100	Copyright 2014-2016 The OpenSSL Project Authors. All Rights Reserved.
	101
4746f25a	102	Licensed under the Apache License 2.0 (the "License"). You may not use
e2f92610 RS	103	this file except in compliance with the License. You can obtain a copy
	104	in the file LICENSE in the source distribution or at
	105	L<https://www.openssl.org/source/license.html>.
	106
	107	=cut