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129.\" ========================================================================
130.\"
131.IX Title "CMS_verify 3"
| 1.\" Automatically generated by Pod::Man 4.07 (Pod::Simple 3.35)
2.\"
3.\" Standard preamble:
4.\" ========================================================================
5.de Sp \" Vertical space (when we can't use .PP)
6.if t .sp .5v
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15.ft R
16.fi
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19.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
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21.\" give a nicer C++. Capital omega is used to do unbreakable dashes and
22.\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff,
23.\" nothing in troff, for use with C<>.
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129.\" ========================================================================
130.\"
131.IX Title "CMS_verify 3"
|
132.TH CMS_verify 3 "2017-11-02" "1.0.2m" "OpenSSL"
| 132.TH CMS_verify 3 "2017-12-07" "1.0.2n" "OpenSSL"
|
133.\" For nroff, turn off justification. Always turn off hyphenation; it makes
134.\" way too many mistakes in technical documents.
135.if n .ad l
136.nh
137.SH "NAME"
138CMS_verify, CMS_get0_signers \- verify a CMS SignedData structure
139.SH "SYNOPSIS"
140.IX Header "SYNOPSIS"
141.Vb 1
142\& #include <openssl/cms.h>
143\&
144\& int CMS_verify(CMS_ContentInfo *cms, STACK_OF(X509) *certs, X509_STORE *store, BIO *indata, BIO *out, unsigned int flags);
145\&
146\& STACK_OF(X509) *CMS_get0_signers(CMS_ContentInfo *cms);
147.Ve
148.SH "DESCRIPTION"
149.IX Header "DESCRIPTION"
150\&\fICMS_verify()\fR verifies a \s-1CMS\s0 SignedData structure. \fBcms\fR is the CMS_ContentInfo
151structure to verify. \fBcerts\fR is a set of certificates in which to search for
152the signing certificate(s). \fBstore\fR is a trusted certificate store used for
153chain verification. \fBindata\fR is the detached content if the content is not
154present in \fBcms\fR. The content is written to \fBout\fR if it is not \s-1NULL.\s0
155.PP
156\&\fBflags\fR is an optional set of flags, which can be used to modify the verify
157operation.
158.PP
159\&\fICMS_get0_signers()\fR retrieves the signing certificate(s) from \fBcms\fR, it must
160be called after a successful \fICMS_verify()\fR operation.
161.SH "VERIFY PROCESS"
162.IX Header "VERIFY PROCESS"
163Normally the verify process proceeds as follows.
164.PP
165Initially some sanity checks are performed on \fBcms\fR. The type of \fBcms\fR must
166be SignedData. There must be at least one signature on the data and if
167the content is detached \fBindata\fR cannot be \fB\s-1NULL\s0\fR.
168.PP
169An attempt is made to locate all the signing certificate(s), first looking in
170the \fBcerts\fR parameter (if it is not \s-1NULL\s0) and then looking in any
171certificates contained in the \fBcms\fR structure itself. If any signing
172certificate cannot be located the operation fails.
173.PP
174Each signing certificate is chain verified using the \fBsmimesign\fR purpose and
175the supplied trusted certificate store. Any internal certificates in the message
176are used as untrusted CAs. If \s-1CRL\s0 checking is enabled in \fBstore\fR any internal
177CRLs are used in addition to attempting to look them up in \fBstore\fR. If any
178chain verify fails an error code is returned.
179.PP
180Finally the signed content is read (and written to \fBout\fR is it is not \s-1NULL\s0)
181and the signature's checked.
182.PP
183If all signature's verify correctly then the function is successful.
184.PP
185Any of the following flags (ored together) can be passed in the \fBflags\fR
186parameter to change the default verify behaviour.
187.PP
188If \fB\s-1CMS_NOINTERN\s0\fR is set the certificates in the message itself are not
189searched when locating the signing certificate(s). This means that all the
190signing certificates must be in the \fBcerts\fR parameter.
191.PP
192If \fB\s-1CMS_NOCRL\s0\fR is set and \s-1CRL\s0 checking is enabled in \fBstore\fR then any
193CRLs in the message itself are ignored.
194.PP
195If the \fB\s-1CMS_TEXT\s0\fR flag is set \s-1MIME\s0 headers for type \fBtext/plain\fR are deleted
196from the content. If the content is not of type \fBtext/plain\fR then an error is
197returned.
198.PP
199If \fB\s-1CMS_NO_SIGNER_CERT_VERIFY\s0\fR is set the signing certificates are not
200verified.
201.PP
202If \fB\s-1CMS_NO_ATTR_VERIFY\s0\fR is set the signed attributes signature is not
203verified.
204.PP
205If \fB\s-1CMS_NO_CONTENT_VERIFY\s0\fR is set then the content digest is not checked.
206.SH "NOTES"
207.IX Header "NOTES"
208One application of \fB\s-1CMS_NOINTERN\s0\fR is to only accept messages signed by
209a small number of certificates. The acceptable certificates would be passed
210in the \fBcerts\fR parameter. In this case if the signer is not one of the
211certificates supplied in \fBcerts\fR then the verify will fail because the
212signer cannot be found.
213.PP
214In some cases the standard techniques for looking up and validating
215certificates are not appropriate: for example an application may wish to
216lookup certificates in a database or perform customised verification. This
217can be achieved by setting and verifying the signers certificates manually
218using the signed data utility functions.
219.PP
220Care should be taken when modifying the default verify behaviour, for example
221setting \fB\s-1CMS_NO_CONTENT_VERIFY\s0\fR will totally disable all content verification
222and any modified content will be considered valid. This combination is however
223useful if one merely wishes to write the content to \fBout\fR and its validity
224is not considered important.
225.PP
226Chain verification should arguably be performed using the signing time rather
227than the current time. However since the signing time is supplied by the
228signer it cannot be trusted without additional evidence (such as a trusted
229timestamp).
230.SH "RETURN VALUES"
231.IX Header "RETURN VALUES"
232\&\fICMS_verify()\fR returns 1 for a successful verification and zero if an error
233occurred.
234.PP
235\&\fICMS_get0_signers()\fR returns all signers or \s-1NULL\s0 if an error occurred.
236.PP
237The error can be obtained from \fIERR_get_error\fR\|(3)
238.SH "BUGS"
239.IX Header "BUGS"
240The trusted certificate store is not searched for the signing certificate,
241this is primarily due to the inadequacies of the current \fBX509_STORE\fR
242functionality.
243.PP
244The lack of single pass processing means that the signed content must all
245be held in memory if it is not detached.
246.SH "SEE ALSO"
247.IX Header "SEE ALSO"
248\&\fIERR_get_error\fR\|(3), \fICMS_sign\fR\|(3)
249.SH "HISTORY"
250.IX Header "HISTORY"
251\&\fICMS_verify()\fR was added to OpenSSL 0.9.8
| 133.\" For nroff, turn off justification. Always turn off hyphenation; it makes
134.\" way too many mistakes in technical documents.
135.if n .ad l
136.nh
137.SH "NAME"
138CMS_verify, CMS_get0_signers \- verify a CMS SignedData structure
139.SH "SYNOPSIS"
140.IX Header "SYNOPSIS"
141.Vb 1
142\& #include <openssl/cms.h>
143\&
144\& int CMS_verify(CMS_ContentInfo *cms, STACK_OF(X509) *certs, X509_STORE *store, BIO *indata, BIO *out, unsigned int flags);
145\&
146\& STACK_OF(X509) *CMS_get0_signers(CMS_ContentInfo *cms);
147.Ve
148.SH "DESCRIPTION"
149.IX Header "DESCRIPTION"
150\&\fICMS_verify()\fR verifies a \s-1CMS\s0 SignedData structure. \fBcms\fR is the CMS_ContentInfo
151structure to verify. \fBcerts\fR is a set of certificates in which to search for
152the signing certificate(s). \fBstore\fR is a trusted certificate store used for
153chain verification. \fBindata\fR is the detached content if the content is not
154present in \fBcms\fR. The content is written to \fBout\fR if it is not \s-1NULL.\s0
155.PP
156\&\fBflags\fR is an optional set of flags, which can be used to modify the verify
157operation.
158.PP
159\&\fICMS_get0_signers()\fR retrieves the signing certificate(s) from \fBcms\fR, it must
160be called after a successful \fICMS_verify()\fR operation.
161.SH "VERIFY PROCESS"
162.IX Header "VERIFY PROCESS"
163Normally the verify process proceeds as follows.
164.PP
165Initially some sanity checks are performed on \fBcms\fR. The type of \fBcms\fR must
166be SignedData. There must be at least one signature on the data and if
167the content is detached \fBindata\fR cannot be \fB\s-1NULL\s0\fR.
168.PP
169An attempt is made to locate all the signing certificate(s), first looking in
170the \fBcerts\fR parameter (if it is not \s-1NULL\s0) and then looking in any
171certificates contained in the \fBcms\fR structure itself. If any signing
172certificate cannot be located the operation fails.
173.PP
174Each signing certificate is chain verified using the \fBsmimesign\fR purpose and
175the supplied trusted certificate store. Any internal certificates in the message
176are used as untrusted CAs. If \s-1CRL\s0 checking is enabled in \fBstore\fR any internal
177CRLs are used in addition to attempting to look them up in \fBstore\fR. If any
178chain verify fails an error code is returned.
179.PP
180Finally the signed content is read (and written to \fBout\fR is it is not \s-1NULL\s0)
181and the signature's checked.
182.PP
183If all signature's verify correctly then the function is successful.
184.PP
185Any of the following flags (ored together) can be passed in the \fBflags\fR
186parameter to change the default verify behaviour.
187.PP
188If \fB\s-1CMS_NOINTERN\s0\fR is set the certificates in the message itself are not
189searched when locating the signing certificate(s). This means that all the
190signing certificates must be in the \fBcerts\fR parameter.
191.PP
192If \fB\s-1CMS_NOCRL\s0\fR is set and \s-1CRL\s0 checking is enabled in \fBstore\fR then any
193CRLs in the message itself are ignored.
194.PP
195If the \fB\s-1CMS_TEXT\s0\fR flag is set \s-1MIME\s0 headers for type \fBtext/plain\fR are deleted
196from the content. If the content is not of type \fBtext/plain\fR then an error is
197returned.
198.PP
199If \fB\s-1CMS_NO_SIGNER_CERT_VERIFY\s0\fR is set the signing certificates are not
200verified.
201.PP
202If \fB\s-1CMS_NO_ATTR_VERIFY\s0\fR is set the signed attributes signature is not
203verified.
204.PP
205If \fB\s-1CMS_NO_CONTENT_VERIFY\s0\fR is set then the content digest is not checked.
206.SH "NOTES"
207.IX Header "NOTES"
208One application of \fB\s-1CMS_NOINTERN\s0\fR is to only accept messages signed by
209a small number of certificates. The acceptable certificates would be passed
210in the \fBcerts\fR parameter. In this case if the signer is not one of the
211certificates supplied in \fBcerts\fR then the verify will fail because the
212signer cannot be found.
213.PP
214In some cases the standard techniques for looking up and validating
215certificates are not appropriate: for example an application may wish to
216lookup certificates in a database or perform customised verification. This
217can be achieved by setting and verifying the signers certificates manually
218using the signed data utility functions.
219.PP
220Care should be taken when modifying the default verify behaviour, for example
221setting \fB\s-1CMS_NO_CONTENT_VERIFY\s0\fR will totally disable all content verification
222and any modified content will be considered valid. This combination is however
223useful if one merely wishes to write the content to \fBout\fR and its validity
224is not considered important.
225.PP
226Chain verification should arguably be performed using the signing time rather
227than the current time. However since the signing time is supplied by the
228signer it cannot be trusted without additional evidence (such as a trusted
229timestamp).
230.SH "RETURN VALUES"
231.IX Header "RETURN VALUES"
232\&\fICMS_verify()\fR returns 1 for a successful verification and zero if an error
233occurred.
234.PP
235\&\fICMS_get0_signers()\fR returns all signers or \s-1NULL\s0 if an error occurred.
236.PP
237The error can be obtained from \fIERR_get_error\fR\|(3)
238.SH "BUGS"
239.IX Header "BUGS"
240The trusted certificate store is not searched for the signing certificate,
241this is primarily due to the inadequacies of the current \fBX509_STORE\fR
242functionality.
243.PP
244The lack of single pass processing means that the signed content must all
245be held in memory if it is not detached.
246.SH "SEE ALSO"
247.IX Header "SEE ALSO"
248\&\fIERR_get_error\fR\|(3), \fICMS_sign\fR\|(3)
249.SH "HISTORY"
250.IX Header "HISTORY"
251\&\fICMS_verify()\fR was added to OpenSSL 0.9.8
|