mirror of
https://github.com/openssl/openssl.git
synced 2024-12-09 05:51:54 +08:00
4746f25ac6
[skip ci] Reviewed-by: Matt Caswell <matt@openssl.org> (Merged from https://github.com/openssl/openssl/pull/7829)
133 lines
4.9 KiB
Plaintext
133 lines
4.9 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
CMS_verify, CMS_get0_signers - verify a CMS SignedData structure
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/cms.h>
|
|
|
|
int CMS_verify(CMS_ContentInfo *cms, STACK_OF(X509) *certs, X509_STORE *store,
|
|
BIO *indata, BIO *out, unsigned int flags);
|
|
|
|
STACK_OF(X509) *CMS_get0_signers(CMS_ContentInfo *cms);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
CMS_verify() verifies a CMS SignedData structure. B<cms> is the CMS_ContentInfo
|
|
structure to verify. B<certs> is a set of certificates in which to search for
|
|
the signing certificate(s). B<store> is a trusted certificate store used for
|
|
chain verification. B<indata> is the detached content if the content is not
|
|
present in B<cms>. The content is written to B<out> if it is not NULL.
|
|
|
|
B<flags> is an optional set of flags, which can be used to modify the verify
|
|
operation.
|
|
|
|
CMS_get0_signers() retrieves the signing certificate(s) from B<cms>, it must
|
|
be called after a successful CMS_verify() operation.
|
|
|
|
=head1 VERIFY PROCESS
|
|
|
|
Normally the verify process proceeds as follows.
|
|
|
|
Initially some sanity checks are performed on B<cms>. The type of B<cms> must
|
|
be SignedData. There must be at least one signature on the data and if
|
|
the content is detached B<indata> cannot be B<NULL>.
|
|
|
|
An attempt is made to locate all the signing certificate(s), first looking in
|
|
the B<certs> parameter (if it is not NULL) and then looking in any
|
|
certificates contained in the B<cms> structure itself. If any signing
|
|
certificate cannot be located the operation fails.
|
|
|
|
Each signing certificate is chain verified using the B<smimesign> purpose and
|
|
the supplied trusted certificate store. Any internal certificates in the message
|
|
are used as untrusted CAs. If CRL checking is enabled in B<store> any internal
|
|
CRLs are used in addition to attempting to look them up in B<store>. If any
|
|
chain verify fails an error code is returned.
|
|
|
|
Finally the signed content is read (and written to B<out> is it is not NULL)
|
|
and the signature's checked.
|
|
|
|
If all signature's verify correctly then the function is successful.
|
|
|
|
Any of the following flags (ored together) can be passed in the B<flags>
|
|
parameter to change the default verify behaviour.
|
|
|
|
If B<CMS_NOINTERN> is set the certificates in the message itself are not
|
|
searched when locating the signing certificate(s). This means that all the
|
|
signing certificates must be in the B<certs> parameter.
|
|
|
|
If B<CMS_NOCRL> is set and CRL checking is enabled in B<store> then any
|
|
CRLs in the message itself are ignored.
|
|
|
|
If the B<CMS_TEXT> flag is set MIME headers for type B<text/plain> are deleted
|
|
from the content. If the content is not of type B<text/plain> then an error is
|
|
returned.
|
|
|
|
If B<CMS_NO_SIGNER_CERT_VERIFY> is set the signing certificates are not
|
|
verified.
|
|
|
|
If B<CMS_NO_ATTR_VERIFY> is set the signed attributes signature is not
|
|
verified.
|
|
|
|
If B<CMS_NO_CONTENT_VERIFY> is set then the content digest is not checked.
|
|
|
|
=head1 NOTES
|
|
|
|
One application of B<CMS_NOINTERN> is to only accept messages signed by
|
|
a small number of certificates. The acceptable certificates would be passed
|
|
in the B<certs> parameter. In this case if the signer is not one of the
|
|
certificates supplied in B<certs> then the verify will fail because the
|
|
signer cannot be found.
|
|
|
|
In some cases the standard techniques for looking up and validating
|
|
certificates are not appropriate: for example an application may wish to
|
|
lookup certificates in a database or perform customised verification. This
|
|
can be achieved by setting and verifying the signers certificates manually
|
|
using the signed data utility functions.
|
|
|
|
Care should be taken when modifying the default verify behaviour, for example
|
|
setting B<CMS_NO_CONTENT_VERIFY> will totally disable all content verification
|
|
and any modified content will be considered valid. This combination is however
|
|
useful if one merely wishes to write the content to B<out> and its validity
|
|
is not considered important.
|
|
|
|
Chain verification should arguably be performed using the signing time rather
|
|
than the current time. However since the signing time is supplied by the
|
|
signer it cannot be trusted without additional evidence (such as a trusted
|
|
timestamp).
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
CMS_verify() returns 1 for a successful verification and zero if an error
|
|
occurred.
|
|
|
|
CMS_get0_signers() returns all signers or NULL if an error occurred.
|
|
|
|
The error can be obtained from L<ERR_get_error(3)>
|
|
|
|
=head1 BUGS
|
|
|
|
The trusted certificate store is not searched for the signing certificate,
|
|
this is primarily due to the inadequacies of the current B<X509_STORE>
|
|
functionality.
|
|
|
|
The lack of single pass processing means that the signed content must all
|
|
be held in memory if it is not detached.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<ERR_get_error(3)>, L<CMS_sign(3)>
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2008-2016 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
|