1=pod 2 3=head1 NAME 4 5PKCS7_sign_add_signer - add a signer PKCS7 signed data structure 6 7=head1 SYNOPSIS 8 9 #include <openssl/pkcs7.h> 10 11 PKCS7_SIGNER_INFO *PKCS7_sign_add_signer(PKCS7 *p7, X509 *signcert, 12 EVP_PKEY *pkey, const EVP_MD *md, int flags); 13 14 15=head1 DESCRIPTION 16 17PKCS7_sign_add_signer() adds a signer with certificate B<signcert> and private 18key B<pkey> using message digest B<md> to a PKCS7 signed data structure 19B<p7>. 20 21The PKCS7 structure should be obtained from an initial call to PKCS7_sign() 22with the flag B<PKCS7_PARTIAL> set or in the case or re-signing a valid PKCS7 23signed data structure. 24 25If the B<md> parameter is B<NULL> then the default digest for the public 26key algorithm will be used. 27 28Unless the B<PKCS7_REUSE_DIGEST> flag is set the returned PKCS7 structure 29is not complete and must be finalized either by streaming (if applicable) or 30a call to PKCS7_final(). 31 32 33=head1 NOTES 34 35The main purpose of this function is to provide finer control over a PKCS#7 36signed data structure where the simpler PKCS7_sign() function defaults are 37not appropriate. For example if multiple signers or non default digest 38algorithms are needed. 39 40Any of the following flags (ored together) can be passed in the B<flags> 41parameter. 42 43If B<PKCS7_REUSE_DIGEST> is set then an attempt is made to copy the content 44digest value from the PKCS7 structure: to add a signer to an existing structure. 45An error occurs if a matching digest value cannot be found to copy. The 46returned PKCS7 structure will be valid and finalized when this flag is set. 47 48If B<PKCS7_PARTIAL> is set in addition to B<PKCS7_REUSE_DIGEST> then the 49B<PKCS7_SIGNER_INO> structure will not be finalized so additional attributes 50can be added. In this case an explicit call to PKCS7_SIGNER_INFO_sign() is 51needed to finalize it. 52 53If B<PKCS7_NOCERTS> is set the signer's certificate will not be included in the 54PKCS7 structure, the signer's certificate must still be supplied in the 55B<signcert> parameter though. This can reduce the size of the signature if the 56signers certificate can be obtained by other means: for example a previously 57signed message. 58 59The signedData structure includes several PKCS#7 authenticatedAttributes 60including the signing time, the PKCS#7 content type and the supported list of 61ciphers in an SMIMECapabilities attribute. If B<PKCS7_NOATTR> is set then no 62authenticatedAttributes will be used. If B<PKCS7_NOSMIMECAP> is set then just 63the SMIMECapabilities are omitted. 64 65If present the SMIMECapabilities attribute indicates support for the following 66algorithms: triple DES, 128 bit RC2, 64 bit RC2, DES and 40 bit RC2. If any of 67these algorithms is disabled then it will not be included. 68 69 70PKCS7_sign_add_signers() returns an internal pointer to the PKCS7_SIGNER_INFO 71structure just added, this can be used to set additional attributes 72before it is finalized. 73 74=head1 RETURN VALUES 75 76PKCS7_sign_add_signers() returns an internal pointer to the PKCS7_SIGNER_INFO 77structure just added or NULL if an error occurs. 78 79=head1 SEE ALSO 80 81L<ERR_get_error(3)>, L<PKCS7_sign(3)>, 82L<PKCS7_final(3)>, 83 84=head1 HISTORY 85 86The PPKCS7_sign_add_signer() function was added in OpenSSL 1.0.0. 87 88=head1 COPYRIGHT 89 90Copyright 2007-2016 The OpenSSL Project Authors. All Rights Reserved. 91 92Licensed under the OpenSSL license (the "License"). You may not use 93this file except in compliance with the License. You can obtain a copy 94in the file LICENSE in the source distribution or at 95L<https://www.openssl.org/source/license.html>. 96 97=cut 98