171 lines
7.1 KiB
Plaintext
171 lines
7.1 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
CMS_verify, CMS_SignedData_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 *detached_data, BIO *out, unsigned int flags);
|
|
BIO *CMS_SignedData_verify(CMS_SignedData *sd, BIO *detached_data,
|
|
STACK_OF(X509) *scerts, X509_STORE *store,
|
|
STACK_OF(X509) *extra, STACK_OF(X509_CRL) *crls,
|
|
unsigned int flags,
|
|
OSSL_LIB_CTX *libctx, const char *propq);
|
|
|
|
STACK_OF(X509) *CMS_get0_signers(CMS_ContentInfo *cms);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
CMS_verify() is very similar to L<PKCS7_verify(3)>. It verifies a
|
|
B<CMS SignedData> structure contained in a structure of type B<CMS_ContentInfo>.
|
|
I<cms> points to the B<CMS_ContentInfo> structure to verify.
|
|
The optional I<certs> parameter refers to a set of certificates
|
|
in which to search for signing certificates.
|
|
I<cms> may contain extra untrusted CA certificates that may be used for
|
|
chain building as well as CRLs that may be used for certificate validation.
|
|
I<store> may be NULL or point to
|
|
the trusted certificate store to use for chain verification.
|
|
I<detached_data> refers to the signed data if the content is detached from I<cms>.
|
|
Otherwise I<detached_data> should be NULL and the signed data must be in I<cms>.
|
|
The content is written to the BIO I<out> unless it is NULL.
|
|
I<flags> is an optional set of flags, which can be used to modify the operation.
|
|
|
|
CMS_SignedData_verify() is like CMS_verify() except that
|
|
it operates on B<CMS SignedData> input in the I<sd> argument,
|
|
it has some additional parameters described next,
|
|
and on success it returns the verified content as a memory BIO.
|
|
The optional I<extra> parameter may be used to provide untrusted CA
|
|
certificates that may be helpful for chain building in certificate validation.
|
|
This list of certificates must not contain duplicates.
|
|
The optional I<crls> parameter may be used to provide extra CRLs.
|
|
Also the list of CRLs must not contain duplicates.
|
|
The optional parameters library context I<libctx> and property query I<propq>
|
|
are used when retrieving algorithms from providers.
|
|
|
|
CMS_get0_signers() retrieves the signing certificate(s) from I<cms>; it may only
|
|
be called after a successful CMS_verify() or CMS_SignedData_verify() operation.
|
|
|
|
=head1 VERIFY PROCESS
|
|
|
|
Normally the verify process proceeds as follows.
|
|
|
|
Initially some sanity checks are performed on I<cms>. The type of I<cms> must
|
|
be SignedData. There must be at least one signature on the data and if
|
|
the content is detached I<detached_data> cannot be NULL.
|
|
|
|
An attempt is made to locate all the signing certificate(s), first looking in
|
|
the I<certs> parameter (if it is not NULL) and then looking in any
|
|
certificates contained in the I<cms> structure unless B<CMS_NOINTERN> is set.
|
|
If any signing certificate cannot be located the operation fails.
|
|
|
|
Each signing certificate is chain verified using the I<smimesign> purpose and
|
|
using the trusted certificate store I<store> if supplied.
|
|
Any internal certificates in the message, which may have been added using
|
|
L<CMS_add1_cert(3)>, are used as untrusted CAs.
|
|
If CRL checking is enabled in I<store> and B<CMS_NOCRL> is not set,
|
|
any internal CRLs, which may have been added using L<CMS_add1_crl(3)>,
|
|
are used in addition to attempting to look them up in I<store>.
|
|
If I<store> is not NULL and any chain verify fails an error code is returned.
|
|
|
|
Finally the signed content is read (and written to I<out> unless it is NULL)
|
|
and the signature is checked.
|
|
|
|
If all signatures verify correctly then the function is successful.
|
|
|
|
Any of the following flags (ored together) can be passed in the I<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 I<certs> parameter.
|
|
|
|
If B<CMS_NOCRL> is set and CRL checking is enabled in I<store> then any
|
|
CRLs in the message itself and provided via the I<crls> parameter are ignored.
|
|
|
|
If the B<CMS_TEXT> flag is set MIME headers for type C<text/plain> are deleted
|
|
from the content. If the content is not of type C<text/plain> then an error is
|
|
returned.
|
|
|
|
If B<CMS_NO_SIGNER_CERT_VERIFY> is set the signing certificates are not
|
|
chain verified, unless B<CMS_CADES> flag is also set.
|
|
|
|
If B<CMS_NO_ATTR_VERIFY> is set the signed attributes signature is not
|
|
verified, unless CMS_CADES flag is also set.
|
|
|
|
If B<CMS_CADES> is set, each signer certificate is checked against the
|
|
ESS signingCertificate or ESS signingCertificateV2 extension
|
|
that is required in the signed attributes of the signature.
|
|
|
|
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 I<certs> parameter. In this case if the signer certificate is not one
|
|
of the certificates supplied in I<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 signer 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 I<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 0 if an error occurred.
|
|
|
|
CMS_SignedData_verify() returns a memory BIO containing the verified content,
|
|
or NULL on error.
|
|
|
|
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<PKCS7_verify(3)>, L<CMS_add1_cert(3)>, L<CMS_add1_crl(3)>,
|
|
L<OSSL_ESS_check_signing_certs(3)>,
|
|
L<ERR_get_error(3)>, L<CMS_sign(3)>
|
|
|
|
=head1 HISTORY
|
|
|
|
CMS_SignedData_verify() was added in OpenSSL 3.2.
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2008-2023 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
|