1CMS_VERIFY(3ossl) OpenSSL CMS_VERIFY(3ossl)
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6 CMS_verify, CMS_get0_signers - verify a CMS SignedData structure
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9 #include <openssl/cms.h>
10 int CMS_verify(CMS_ContentInfo *cms, STACK_OF(X509) *certs, X509_STORE *store,
12 BIO *indata, BIO *out, unsigned int flags);
13 STACK_OF(X509) *CMS_get0_signers(CMS_ContentInfo *cms);
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17 CMS_verify() verifies a CMS SignedData structure. cms is the
18 CMS_ContentInfo structure to verify. certs is a set of certificates in
19 which to search for the signing certificate(s). store is a trusted
20 certificate store used for chain verification. indata is the detached
21 content if the content is not present in cms. The content is written to
22 out if it is not NULL.
23 flags is an optional set of flags, which can be used to modify the
25 verify operation.
26 CMS_get0_signers() retrieves the signing certificate(s) from cms, it
28 may only be called after a successful CMS_verify() operation.
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31 Normally the verify process proceeds as follows.
32 Initially some sanity checks are performed on cms. The type of cms must
34 be SignedData. There must be at least one signature on the data and if
35 the content is detached indata cannot be NULL.
36 An attempt is made to locate all the signing certificate(s), first
38 looking in the certs parameter (if it is not NULL) and then looking in
39 any certificates contained in the cms structure itself. If any signing
40 certificate cannot be located the operation fails.
41 Each signing certificate is chain verified using the smimesign purpose
43 and the supplied trusted certificate store. Any internal certificates
44 in the message are used as untrusted CAs. If CRL checking is enabled in
45 store any internal CRLs are used in addition to attempting to look them
46 up in store. If any chain verify fails an error code is returned.
47 Finally the signed content is read (and written to out if it is not
49 NULL) and the signature's checked.
50 If all signature's verify correctly then the function is successful.
52 Any of the following flags (ored together) can be passed in the flags
54 parameter to change the default verify behaviour.
55 If CMS_NOINTERN is set the certificates in the message itself are not
57 searched when locating the signing certificate(s). This means that all
58 the signing certificates must be in the certs parameter.
59 If CMS_NOCRL is set and CRL checking is enabled in store then any CRLs
61 in the message itself are ignored.
62 If the CMS_TEXT flag is set MIME headers for type text/plain are
64 deleted from the content. If the content is not of type text/plain then
65 an error is returned.
66 If CMS_NO_SIGNER_CERT_VERIFY is set the signing certificates are not
68 verified, unless CMS_CADES flag is also set.
69 If CMS_NO_ATTR_VERIFY is set the signed attributes signature is not
71 verified, unless CMS_CADES flag is also set.
72 If CMS_CADES is set, each signer certificate is checked against the ESS
74 signingCertificate or ESS signingCertificateV2 extension that is
75 required in the signed attributes of the signature.
76 If CMS_NO_CONTENT_VERIFY is set then the content digest is not checked.
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80 One application of CMS_NOINTERN is to only accept messages signed by a
81 small number of certificates. The acceptable certificates would be
82 passed in the certs parameter. In this case if the signer is not one of
83 the certificates supplied in certs then the verify will fail because
84 the signer cannot be found.
85 In some cases the standard techniques for looking up and validating
87 certificates are not appropriate: for example an application may wish
88 to lookup certificates in a database or perform customised
89 verification. This can be achieved by setting and verifying the signers
90 certificates manually using the signed data utility functions.
91 Care should be taken when modifying the default verify behaviour, for
93 example setting CMS_NO_CONTENT_VERIFY will totally disable all content
94 verification and any modified content will be considered valid. This
95 combination is however useful if one merely wishes to write the content
96 to out and its validity is not considered important.
97 Chain verification should arguably be performed using the signing time
99 rather than the current time. However, since the signing time is
100 supplied by the signer it cannot be trusted without additional evidence
101 (such as a trusted timestamp).
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104 CMS_verify() returns 1 for a successful verification and zero if an
105 error occurred.
106 CMS_get0_signers() returns all signers or NULL if an error occurred.
108 The error can be obtained from ERR_get_error(3)
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112 The trusted certificate store is not searched for the signing
113 certificate, this is primarily due to the inadequacies of the current
114 X509_STORE functionality.
115 The lack of single pass processing means that the signed content must
117 all be held in memory if it is not detached.
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120 OSSL_ESS_check_signing_certs(3), ERR_get_error(3), CMS_sign(3)
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123 Copyright 2008-2021 The OpenSSL Project Authors. All Rights Reserved.
124 Licensed under the Apache License 2.0 (the "License"). You may not use
126 this file except in compliance with the License. You can obtain a copy
127 in the file LICENSE in the source distribution or at
128 <https://www.openssl.org/source/license.html>.
1293.0.5 2022-07-05 CMS_VERIFY(3ossl)