mirror of
https://github.com/openssl/openssl.git
synced 2024-12-15 06:01:37 +08:00
e9b7724687
I tried hard to keep the lines at 80 characters or less, but in a few cases I had to punt and just indented the subsequent lines by 4 spaces. A few well-placed typedefs for callback functions would really help, but these would be part of the API, so that's probably for later. I also took the liberty of inserting empty lines in overlong blocks to provide some visual space. Reviewed-by: Rich Salz <rsalz@openssl.org> Reviewed-by: Matt Caswell <matt@openssl.org> (Merged from https://github.com/openssl/openssl/pull/1956)
130 lines
5.2 KiB
Plaintext
130 lines
5.2 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
CMS_sign - create a CMS SignedData structure
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/cms.h>
|
|
|
|
CMS_ContentInfo *CMS_sign(X509 *signcert, EVP_PKEY *pkey, STACK_OF(X509) *certs,
|
|
BIO *data, unsigned int flags);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
CMS_sign() creates and returns a CMS SignedData structure. B<signcert> is
|
|
the certificate to sign with, B<pkey> is the corresponding private key.
|
|
B<certs> is an optional additional set of certificates to include in the CMS
|
|
structure (for example any intermediate CAs in the chain). Any or all of
|
|
these parameters can be B<NULL>, see B<NOTES> below.
|
|
|
|
The data to be signed is read from BIO B<data>.
|
|
|
|
B<flags> is an optional set of flags.
|
|
|
|
=head1 NOTES
|
|
|
|
Any of the following flags (ored together) can be passed in the B<flags>
|
|
parameter.
|
|
|
|
Many S/MIME clients expect the signed content to include valid MIME headers. If
|
|
the B<CMS_TEXT> flag is set MIME headers for type B<text/plain> are prepended
|
|
to the data.
|
|
|
|
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 data being signed is included in the CMS_ContentInfo structure, unless
|
|
B<CMS_DETACHED> is set in which case it is omitted. This is used for
|
|
CMS_ContentInfo detached signatures which are used in S/MIME plaintext signed
|
|
messages for example.
|
|
|
|
Normally the supplied content is translated into MIME canonical format (as
|
|
required by the S/MIME specifications) if B<CMS_BINARY> is set no translation
|
|
occurs. This option should be used if the supplied data is in binary format
|
|
otherwise the translation will corrupt it.
|
|
|
|
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.
|
|
|
|
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.
|
|
|
|
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 the flags B<CMS_STREAM> is set then the returned B<CMS_ContentInfo>
|
|
structure is just initialized ready to perform the signing operation. The
|
|
signing is however B<not> performed and the data to be signed is not read from
|
|
the B<data> parameter. Signing is deferred until after the data has been
|
|
written. In this way data can be signed in a single pass.
|
|
|
|
If the B<CMS_PARTIAL> flag is set a partial B<CMS_ContentInfo> structure is
|
|
output to which additional signers and capabilities can be added before
|
|
finalization.
|
|
|
|
If the flag B<CMS_STREAM> is set the returned B<CMS_ContentInfo> structure is
|
|
B<not> complete and outputting its contents via a function that does not
|
|
properly finalize the B<CMS_ContentInfo> structure will give unpredictable
|
|
results.
|
|
|
|
Several functions including SMIME_write_CMS(), i2d_CMS_bio_stream(),
|
|
PEM_write_bio_CMS_stream() finalize the structure. Alternatively finalization
|
|
can be performed by obtaining the streaming ASN1 B<BIO> directly using
|
|
BIO_new_CMS().
|
|
|
|
If a signer is specified it will use the default digest for the signing
|
|
algorithm. This is B<SHA1> for both RSA and DSA keys.
|
|
|
|
If B<signcert> and B<pkey> are NULL then a certificates only CMS structure is
|
|
output.
|
|
|
|
The function CMS_sign() is a basic CMS signing function whose output will be
|
|
suitable for many purposes. For finer control of the output format the
|
|
B<certs>, B<signcert> and B<pkey> parameters can all be B<NULL> and the
|
|
B<CMS_PARTIAL> flag set. Then one or more signers can be added using the
|
|
function CMS_sign_add1_signer(), non default digests can be used and custom
|
|
attributes added. CMS_final() must then be called to finalize the
|
|
structure if streaming is not enabled.
|
|
|
|
=head1 BUGS
|
|
|
|
Some attributes such as counter signatures are not supported.
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
CMS_sign() returns either a valid CMS_ContentInfo structure or NULL if an error
|
|
occurred. The error can be obtained from ERR_get_error(3).
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<ERR_get_error(3)>, L<CMS_verify(3)>
|
|
|
|
=head1 HISTORY
|
|
|
|
The B<CMS_STREAM> flag is only supported for detached data in OpenSSL 0.9.8,
|
|
it is supported for embedded data in OpenSSL 1.0.0 and later.
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2008-2016 The OpenSSL Project Authors. All Rights Reserved.
|
|
|
|
Licensed under the OpenSSL license (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
|