1PKCS7_SIGN(3) OpenSSL PKCS7_SIGN(3)
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6 PKCS7_sign - create a PKCS#7 signedData structure
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9 #include <openssl/pkcs7.h>
10 PKCS7 *PKCS7_sign(X509 *signcert, EVP_PKEY *pkey, STACK_OF(X509) *certs,
12 BIO *data, int flags);
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15 PKCS7_sign() creates and returns a PKCS#7 signedData structure.
16 signcert is the certificate to sign with, pkey is the corresponding
17 private key. certs is an optional additional set of certificates to
18 include in the PKCS#7 structure (for example any intermediate CAs in
19 the chain).
20 The data to be signed is read from BIO data.
22 flags is an optional set of flags.
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26 Any of the following flags (ored together) can be passed in the flags
27 parameter.
28 Many S/MIME clients expect the signed content to include valid MIME
30 headers. If the PKCS7_TEXT flag is set MIME headers for type text/plain
31 are prepended to the data.
32 If PKCS7_NOCERTS is set the signer's certificate will not be included
34 in the PKCS7 structure, the signer's certificate must still be supplied
35 in the signcert parameter though. This can reduce the size of the
36 signature if the signers certificate can be obtained by other means:
37 for example a previously signed message.
38 The data being signed is included in the PKCS7 structure, unless
40 PKCS7_DETACHED is set in which case it is omitted. This is used for
41 PKCS7 detached signatures which are used in S/MIME plaintext signed
42 messages for example.
43 Normally the supplied content is translated into MIME canonical format
45 (as required by the S/MIME specifications) if PKCS7_BINARY is set no
46 translation occurs. This option should be used if the supplied data is
47 in binary format otherwise the translation will corrupt it.
48 The signedData structure includes several PKCS#7
50 authenticatedAttributes including the signing time, the PKCS#7 content
51 type and the supported list of ciphers in an SMIMECapabilities
52 attribute. If PKCS7_NOATTR is set then no authenticatedAttributes will
53 be used. If PKCS7_NOSMIMECAP is set then just the SMIMECapabilities are
54 omitted.
55 If present the SMIMECapabilities attribute indicates support for the
57 following algorithms: triple DES, 128 bit RC2, 64 bit RC2, DES and 40
58 bit RC2. If any of these algorithms is disabled then it will not be
59 included.
60 If the flags PKCS7_STREAM is set then the returned PKCS7 structure is
62 just initialized ready to perform the signing operation. The signing is
63 however not performed and the data to be signed is not read from the
64 data parameter. Signing is deferred until after the data has been
65 written. In this way data can be signed in a single pass.
66 If the PKCS7_PARTIAL flag is set a partial PKCS7 structure is output to
68 which additional signers and capabilities can be added before
69 finalization.
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72 If the flag PKCS7_STREAM is set the returned PKCS7 structure is not
73 complete and outputting its contents via a function that does not
74 properly finalize the PKCS7 structure will give unpredictable results.
75 Several functions including SMIME_write_PKCS7(),
77 i2d_PKCS7_bio_stream(), PEM_write_bio_PKCS7_stream() finalize the
78 structure. Alternatively finalization can be performed by obtaining the
79 streaming ASN1 BIO directly using BIO_new_PKCS7().
80 If a signer is specified it will use the default digest for the signing
82 algorithm. This is SHA1 for both RSA and DSA keys.
83 The certs, signcert and pkey parameters can all be NULL if the
85 PKCS7_PARTIAL flag is set. One or more signers can be added using the
86 function PKCS7_sign_add_signer(). PKCS7_final() must also be called to
87 finalize the structure if streaming is not enabled. Alternative signing
88 digests can also be specified using this method.
89 If signcert and pkey are NULL then a certificates only PKCS#7 structure
91 is output.
92 In versions of OpenSSL before 1.0.0 the signcert and pkey parameters
94 must NOT be NULL.
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97 Some advanced attributes such as counter signatures are not supported.
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100 PKCS7_sign() returns either a valid PKCS7 structure or NULL if an error
101 occurred. The error can be obtained from ERR_get_error(3).
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104 ERR_get_error(3), PKCS7_verify(3)
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107 The PKCS7_PARTIAL flag, and the ability for certs, signcert, and pkey
108 parameters to be NULL were added in OpenSSL 1.0.0.
109 The PKCS7_STREAM flag was added in OpenSSL 1.0.0.
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113 Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved.
114 Licensed under the OpenSSL license (the "License"). You may not use
116 this file except in compliance with the License. You can obtain a copy
117 in the file LICENSE in the source distribution or at
118 <https://www.openssl.org/source/license.html>.
1191.1.1i 2021-07-22 PKCS7_SIGN(3)