116 lines
4.3 KiB
Text
116 lines
4.3 KiB
Text
=pod
|
|
|
|
=head1 NAME
|
|
|
|
PKCS7_sign - create a PKCS#7 signedData structure
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/pkcs7.h>
|
|
|
|
PKCS7 *PKCS7_sign(X509 *signcert, EVP_PKEY *pkey, STACK_OF(X509) *certs, BIO *data, int flags);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
PKCS7_sign() creates and returns a PKCS#7 signedData structure. B<signcert> is
|
|
the certificate to sign with, B<pkey> is the corresponsding private key.
|
|
B<certs> is an optional additional set of certificates to include in the PKCS#7
|
|
structure (for example any intermediate CAs in the chain).
|
|
|
|
The data to be signed is read from BIO B<data>.
|
|
|
|
B<flags> is an optional set of flags.
|
|
|
|
=head1 NOTES
|
|
|
|
Any of the following flags (ored together) can be passed in the B<flags>
|
|
parameter.
|
|
|
|
Many S/MIME clients expect the signed content to include valid MIME headers. If
|
|
the B<PKCS7_TEXT> flag is set MIME headers for type B<text/plain> are prepended
|
|
to the data.
|
|
|
|
If B<PKCS7_NOCERTS> is set the signer's certificate will not be included in the
|
|
PKCS7 structure, the signer's certificate must still be supplied in the
|
|
B<signcert> parameter though. This can reduce the size of the signature if the
|
|
signers certificate can be obtained by other means: for example a previously
|
|
signed message.
|
|
|
|
The data being signed is included in the PKCS7 structure, unless
|
|
B<PKCS7_DETACHED> is set in which case it is omitted. This is used for PKCS7
|
|
detached signatures which are used in S/MIME plaintext signed messages for
|
|
example.
|
|
|
|
Normally the supplied content is translated into MIME canonical format (as
|
|
required by the S/MIME specifications) if B<PKCS7_BINARY> is set no translation
|
|
occurs. This option should be used if the supplied data is in binary format
|
|
otherwise the translation will corrupt it.
|
|
|
|
The signedData structure includes several PKCS#7 autenticatedAttributes
|
|
including the signing time, the PKCS#7 content type and the supported list of
|
|
ciphers in an SMIMECapabilities attribute. If B<PKCS7_NOATTR> is set then no
|
|
authenticatedAttributes will be used. If B<PKCS7_NOSMIMECAP> is set then just
|
|
the SMIMECapabilities are omitted.
|
|
|
|
If present the SMIMECapabilities attribute indicates support for the following
|
|
algorithms: triple DES, 128 bit RC2, 64 bit RC2, DES and 40 bit RC2. If any of
|
|
these algorithms is disabled then it will not be included.
|
|
|
|
If the flags B<PKCS7_STREAM> is set then the returned B<PKCS7> structure is
|
|
just initialized ready to perform the signing operation. The signing is however
|
|
B<not> performed and the data to be signed is not read from the B<data>
|
|
parameter. Signing is deferred until after the data has been written. In this
|
|
way data can be signed in a single pass.
|
|
|
|
If the B<PKCS7_PARTIAL> flag is set a partial B<PKCS7> structure is output to
|
|
which additional signers and capabilities can be added before finalization.
|
|
|
|
|
|
=head1 NOTES
|
|
|
|
If the flag B<PKCS7_STREAM> is set the returned B<PKCS7> structure is B<not>
|
|
complete and outputting its contents via a function that does not properly
|
|
finalize the B<PKCS7> structure will give unpredictable results.
|
|
|
|
Several functions including SMIME_write_PKCS7(), d2i_PKCS7_bio_stream(),
|
|
PEM_write_bio_PKCS7_stream() finalize the structure. Alternatively finalization
|
|
can be performed by obtaining the streaming ASN1 B<BIO> directly using
|
|
BIO_new_PKCS7().
|
|
|
|
If a signer is specified it will use the default digest for the signing
|
|
algorithm. This is B<SHA1> for both RSA and DSA keys.
|
|
|
|
In OpenSSL 0.9.9 the B<certs>, B<signcert> and B<pkey> parameters can all be
|
|
B<NULL> if the B<PKCS7_PARTIAL> flag is set. One or more signers can be added
|
|
using the function B<PKCS7_sign_add_signer()>. B<PKCS7_final()> must also be
|
|
called to finalize the structure if streaming is not enabled. Alternative
|
|
signing digests can also be specified using this method.
|
|
|
|
In OpenSSL 0.9.9 if B<signcert> and B<pkey> are NULL then a certificates only
|
|
PKCS#7 structure is output.
|
|
|
|
In versions of OpenSSL before 0.9.9 the B<signcert> and B<pkey> parameters must
|
|
B<NOT> be NULL.
|
|
|
|
=head1 BUGS
|
|
|
|
Some advanced attributes such as counter signatures are not supported.
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
PKCS7_sign() returns either a valid PKCS7 structure or NULL if an error
|
|
occurred. The error can be obtained from ERR_get_error(3).
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<ERR_get_error(3)|ERR_get_error(3)>, L<PKCS7_verify(3)|PKCS7_verify(3)>
|
|
|
|
=head1 HISTORY
|
|
|
|
PKCS7_sign() was added to OpenSSL 0.9.5
|
|
|
|
The B<PKCS7_PARTIAL> flag was added in OpenSSL 0.9.9
|
|
|
|
The B<PKCS7_STREAM> flag was added in OpenSSL 0.9.9
|
|
|
|
=cut
|