5 PKCS7_sign - create a PKCS#7 signedData structure
9 #include <openssl/pkcs7.h>
11 PKCS7 *PKCS7_sign(X509 *signcert, EVP_PKEY *pkey, STACK_OF(X509) *certs,
12 BIO *data, int flags);
16 PKCS7_sign() creates and returns a PKCS#7 signedData structure. B<signcert> is
17 the certificate to sign with, B<pkey> is the corresponding private key.
18 B<certs> is an optional additional set of certificates to include in the PKCS#7
19 structure (for example any intermediate CAs in the chain).
21 The data to be signed is read from BIO B<data>.
23 B<flags> is an optional set of flags.
27 Any of the following flags (ored together) can be passed in the B<flags>
30 Many S/MIME clients expect the signed content to include valid MIME headers. If
31 the B<PKCS7_TEXT> flag is set MIME headers for type B<text/plain> are prepended
34 If B<PKCS7_NOCERTS> is set the signer's certificate will not be included in the
35 PKCS7 structure, the signer's certificate must still be supplied in the
36 B<signcert> parameter though. This can reduce the size of the signature if the
37 signers certificate can be obtained by other means: for example a previously
40 The data being signed is included in the PKCS7 structure, unless
41 B<PKCS7_DETACHED> is set in which case it is omitted. This is used for PKCS7
42 detached signatures which are used in S/MIME plaintext signed messages for
45 Normally the supplied content is translated into MIME canonical format (as
46 required by the S/MIME specifications) if B<PKCS7_BINARY> is set no translation
47 occurs. This option should be used if the supplied data is in binary format
48 otherwise the translation will corrupt it.
50 The signedData structure includes several PKCS#7 authenticatedAttributes
51 including the signing time, the PKCS#7 content type and the supported list of
52 ciphers in an SMIMECapabilities attribute. If B<PKCS7_NOATTR> is set then no
53 authenticatedAttributes will be used. If B<PKCS7_NOSMIMECAP> is set then just
54 the SMIMECapabilities are omitted.
56 If present the SMIMECapabilities attribute indicates support for the following
57 algorithms: triple DES, 128 bit RC2, 64 bit RC2, DES and 40 bit RC2. If any of
58 these algorithms is disabled then it will not be included.
60 If the flags B<PKCS7_STREAM> is set then the returned B<PKCS7> structure is
61 just initialized ready to perform the signing operation. The signing is however
62 B<not> performed and the data to be signed is not read from the B<data>
63 parameter. Signing is deferred until after the data has been written. In this
64 way data can be signed in a single pass.
66 If the B<PKCS7_PARTIAL> flag is set a partial B<PKCS7> structure is output to
67 which additional signers and capabilities can be added before finalization.
71 If the flag B<PKCS7_STREAM> is set the returned B<PKCS7> structure is B<not>
72 complete and outputting its contents via a function that does not properly
73 finalize the B<PKCS7> structure will give unpredictable results.
75 Several functions including SMIME_write_PKCS7(), i2d_PKCS7_bio_stream(),
76 PEM_write_bio_PKCS7_stream() finalize the structure. Alternatively finalization
77 can be performed by obtaining the streaming ASN1 B<BIO> directly using
80 If a signer is specified it will use the default digest for the signing
81 algorithm. This is B<SHA1> for both RSA and DSA keys.
83 The B<certs>, B<signcert> and B<pkey> parameters can all be
84 B<NULL> if the B<PKCS7_PARTIAL> flag is set. One or more signers can be added
85 using the function PKCS7_sign_add_signer(). PKCS7_final() must also be
86 called to finalize the structure if streaming is not enabled. Alternative
87 signing digests can also be specified using this method.
89 If B<signcert> and B<pkey> are NULL then a certificates only
90 PKCS#7 structure is output.
92 In versions of OpenSSL before 1.0.0 the B<signcert> and B<pkey> parameters must
97 Some advanced attributes such as counter signatures are not supported.
101 PKCS7_sign() returns either a valid PKCS7 structure or NULL if an error
102 occurred. The error can be obtained from ERR_get_error(3).
106 L<ERR_get_error(3)>, L<PKCS7_verify(3)>
110 The B<PKCS7_PARTIAL> flag, and the ability for B<certs>, B<signcert>,
111 and B<pkey> parameters to be B<NULL> to be was added in OpenSSL 1.0.0
113 The B<PKCS7_STREAM> flag was added in OpenSSL 1.0.0
117 Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved.
119 Licensed under the OpenSSL license (the "License"). You may not use
120 this file except in compliance with the License. You can obtain a copy
121 in the file LICENSE in the source distribution or at
122 L<https://www.openssl.org/source/license.html>.