PKCS7_SIGN(3ossl) OpenSSL PKCS7_SIGN(3ossl)
NAME
PKCS7_sign_ex, PKCS7_sign - create a PKCS#7 signedData structure
SYNOPSIS
#include <openssl/pkcs7.h>
PKCS7 *PKCS7_sign_ex(X509 *signcert, EVP_PKEY *pkey, STACK_OF(X509) *certs,
BIO *data, int flags, OSSL_LIB_CTX *libctx,
const char *propq);
PKCS7 *PKCS7_sign(X509 *signcert, EVP_PKEY *pkey, STACK_OF(X509) *certs,
BIO *data, int flags);
DESCRIPTION
PKCS7_sign_ex() creates and returns a PKCS#7 signedData structure.
signcert is the certificate to sign with, pkey is the corresponding
private key. certs is an optional set of extra certificates to include
in the PKCS#7 structure (for example any intermediate CAs in the
chain). The library context libctx and property query propq are used
when retrieving algorithms from providers.
The data to be signed is read from BIO data.
flags is an optional set of flags.
Any of the following flags (ored together) can be passed in the flags
parameter.
Many S/MIME clients expect the signed content to include valid MIME
headers. If the PKCS7_TEXT flag is set MIME headers for type
"text/plain" are prepended to the data.
If PKCS7_NOCERTS is set the signer's certificate and the extra certs
will not be included in the PKCS7 structure. The signer's certificate
must still be supplied in the signcert parameter though. This can
reduce the size of the signatures if the signer's certificates can be
obtained by other means: for example a previously signed message.
The data being signed is included in the PKCS7 structure, unless
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 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
authenticatedAttributes including the signing time, the PKCS#7 content
type and the supported list of ciphers in an SMIMECapabilities
attribute. If PKCS7_NOATTR is set then no authenticatedAttributes will
be used. If 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 PKCS7_STREAM is set then the returned PKCS7 structure is
just initialized ready to perform the signing operation. The signing is
however not performed and the data to be signed is not read from the
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 PKCS7_PARTIAL flag is set a partial PKCS7 structure is output to
which additional signers and capabilities can be added before
finalization.
If the flag PKCS7_STREAM is set the returned PKCS7 structure is not
complete and outputting its contents via a function that does not
properly finalize the PKCS7 structure will give unpredictable results.
Several functions including SMIME_write_PKCS7(),
i2d_PKCS7_bio_stream(), PEM_write_bio_PKCS7_stream() finalize the
structure. Alternatively finalization can be performed by obtaining the
streaming ASN1 BIO directly using BIO_new_PKCS7().
If a signer is specified it will use the default digest for the signing
algorithm. This is SHA1 for both RSA and DSA keys.
The certs, signcert and pkey parameters can all be NULL if the
PKCS7_PARTIAL flag is set. One or more signers can be added using the
function PKCS7_sign_add_signer(). 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.
If signcert and pkey are NULL then a certificates only PKCS#7 structure
is output.
In versions of OpenSSL before 1.0.0 the signcert and pkey parameters
must not be NULL.
PKCS7_sign(3) is like PKCS7_sign_ex() except that it uses default values
of NULL for the library context libctx and the property query propq.
This is retained for API backward compatibility.
BUGS
Some advanced attributes such as counter signatures are not supported.
RETURN VALUES
PKCS7_sign(3) return either a valid PKCS7 structure
or NULL if an error occurred. The error can be obtained from
ERR_get_error(3).
SEE ALSO
ERR_get_error(3), PKCS7_verify(3)
HISTORY
The function PKCS7_sign_ex() was added in OpenSSL 3.0.
The PKCS7_PARTIAL flag, and the ability for certs, signcert, and pkey
parameters to be NULL were added in OpenSSL 1.0.0.
The PKCS7_STREAM flag was added in OpenSSL 1.0.0.
COPYRIGHT
Copyright 2002-2023 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
<https://www.openssl.org/source/license.html>.
3.3.2 2024-09-04 PKCS7_SIGN(3ossl)
openssl 3.3.2 - Generated Thu Sep 19 15:46:17 CDT 2024