doc/man3/PKCS7_verify.pod - third_party/openssl - Git at Google

 =pod

 =head1 NAME

 PKCS7_verify, PKCS7_get0_signers - verify a PKCS#7 signedData structure

 =head1 SYNOPSIS

  #include <openssl/pkcs7.h>

  int PKCS7_verify(PKCS7 *p7, STACK_OF(X509) *certs, X509_STORE *store,
                   BIO *indata, BIO *out, int flags);

  STACK_OF(X509) *PKCS7_get0_signers(PKCS7 *p7, STACK_OF(X509) *certs, int flags);

 =head1 DESCRIPTION

 PKCS7_verify() verifies a PKCS#7 signedData structure. B<p7> is the PKCS7
 structure to verify. B<certs> is a set of certificates in which to search for
 the signer's certificate. B<store> is a trusted certificate store (used for
 chain verification). B<indata> is the signed data if the content is not
 present in B<p7> (that is it is detached). 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.

 PKCS7_get0_signers() retrieves the signer's certificates from B<p7>, it does
 B<not> check their validity or whether any signatures are valid. The B<certs>
 and B<flags> parameters have the same meanings as in PKCS7_verify().

 =head1 VERIFY PROCESS

 Normally the verify process proceeds as follows.

 Initially some sanity checks are performed on B<p7>. The type of B<p7> 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>.  If the content is
 not detached and B<indata> is not B<NULL>, then the structure has both
 embedded and external content. To treat this as an error, use the flag
 B<PKCS7_NO_DUAL_CONTENT>.
 The default behavior allows this, for compatibility with older
 versions of OpenSSL.

 An attempt is made to locate all the signer's certificates, first looking in
 the B<certs> parameter (if it is not B<NULL>) and then looking in any certificates
 contained in the B<p7> structure itself. If any signer's certificates cannot be
 located the operation fails.

 Each signer's 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 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. Only the flag B<PKCS7_NOINTERN> is
 meaningful to PKCS7_get0_signers().

 If B<PKCS7_NOINTERN> is set the certificates in the message itself are not
 searched when locating the signer's certificate. This means that all the signers
 certificates must be in the B<certs> parameter.

 If the B<PKCS7_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<PKCS7_NOVERIFY> is set the signer's certificates are not chain verified.

 If B<PKCS7_NOCHAIN> is set then the certificates contained in the message are
 not used as untrusted CAs. This means that the whole verify chain (apart from
 the signer's certificate) must be contained in the trusted store.

 If B<PKCS7_NOSIGS> is set then the signatures on the data are not checked.

 =head1 NOTES

 One application of B<PKCS7_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.

 Care should be taken when modifying the default verify behaviour, for example
 setting C<PKCS7_NOVERIFY|PKCS7_NOSIGS> will totally disable all verification
 and any signed message 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

 PKCS7_verify() returns one for a successful verification and zero
 if an error occurs.

 PKCS7_get0_signers() returns all signers or B<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 signers certificate,
 this is primarily due to the inadequacies of the current B<X509_STORE>
 functionality.

 The lack of single pass processing and need to hold all data in memory as
 mentioned in PKCS7_sign() also applies to PKCS7_verify().

 =head1 SEE ALSO

 L<ERR_get_error(3)>, L<PKCS7_sign(3)>

 =head1 COPYRIGHT

 Copyright 2002-2020 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
	=pod

	=head1 NAME

	PKCS7_verify, PKCS7_get0_signers - verify a PKCS#7 signedData structure

	=head1 SYNOPSIS

	#include <openssl/pkcs7.h>

	int PKCS7_verify(PKCS7 p7, STACK_OF(X509) certs, X509_STORE *store,
	BIO indata, BIO out, int flags);

	STACK_OF(X509) PKCS7_get0_signers(PKCS7 p7, STACK_OF(X509) *certs, int flags);

	=head1 DESCRIPTION

	PKCS7_verify() verifies a PKCS#7 signedData structure. B<p7> is the PKCS7
	structure to verify. B<certs> is a set of certificates in which to search for
	the signer's certificate. B<store> is a trusted certificate store (used for
	chain verification). B<indata> is the signed data if the content is not
	present in B<p7> (that is it is detached). 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.

	PKCS7_get0_signers() retrieves the signer's certificates from B<p7>, it does
	B<not> check their validity or whether any signatures are valid. The B<certs>
	and B<flags> parameters have the same meanings as in PKCS7_verify().

	=head1 VERIFY PROCESS

	Normally the verify process proceeds as follows.

	Initially some sanity checks are performed on B<p7>. The type of B<p7> 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>. If the content is
	not detached and B<indata> is not B<NULL>, then the structure has both
	embedded and external content. To treat this as an error, use the flag
	B<PKCS7_NO_DUAL_CONTENT>.
	The default behavior allows this, for compatibility with older
	versions of OpenSSL.

	An attempt is made to locate all the signer's certificates, first looking in
	the B<certs> parameter (if it is not B<NULL>) and then looking in any certificates
	contained in the B<p7> structure itself. If any signer's certificates cannot be
	located the operation fails.

	Each signer's 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 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. Only the flag B<PKCS7_NOINTERN> is
	meaningful to PKCS7_get0_signers().

	If B<PKCS7_NOINTERN> is set the certificates in the message itself are not
	searched when locating the signer's certificate. This means that all the signers
	certificates must be in the B<certs> parameter.

	If the B<PKCS7_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<PKCS7_NOVERIFY> is set the signer's certificates are not chain verified.

	If B<PKCS7_NOCHAIN> is set then the certificates contained in the message are
	not used as untrusted CAs. This means that the whole verify chain (apart from
	the signer's certificate) must be contained in the trusted store.

	If B<PKCS7_NOSIGS> is set then the signatures on the data are not checked.

	=head1 NOTES

	One application of B<PKCS7_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.

	Care should be taken when modifying the default verify behaviour, for example
	setting C<PKCS7_NOVERIFY\|PKCS7_NOSIGS> will totally disable all verification
	and any signed message 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

	PKCS7_verify() returns one for a successful verification and zero
	if an error occurs.

	PKCS7_get0_signers() returns all signers or B<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 signers certificate,
	this is primarily due to the inadequacies of the current B<X509_STORE>
	functionality.

	The lack of single pass processing and need to hold all data in memory as
	mentioned in PKCS7_sign() also applies to PKCS7_verify().

	=head1 SEE ALSO

	L<ERR_get_error(3)>, L<PKCS7_sign(3)>

	=head1 COPYRIGHT

	Copyright 2002-2020 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