.\" $OpenBSD: CMS_add1_signer.3,v 1.3 2019/08/10 23:41:22 schwarze Exp $ .\" full merge up to: OpenSSL e9b77246 Jan 20 19:58:49 2017 +0100 .\" .\" This file was written by Dr. Stephen Henson . .\" Copyright (c) 2008 The OpenSSL Project. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in .\" the documentation and/or other materials provided with the .\" distribution. .\" .\" 3. 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IN NO EVENT SHALL THE OpenSSL PROJECT OR .\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED .\" OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd $Mdocdate: August 10 2019 $ .Dt CMS_ADD1_SIGNER 3 .Os .Sh NAME .Nm CMS_add1_signer , .Nm CMS_SignerInfo_sign .Nd add a signer to a CMS_ContentInfo signed data structure .Sh SYNOPSIS .In openssl/cms.h .Ft CMS_SignerInfo * .Fo CMS_add1_signer .Fa "CMS_ContentInfo *cms" .Fa "X509 *signcert" .Fa "EVP_PKEY *pkey" .Fa "const EVP_MD *md" .Fa "unsigned int flags" .Fc .Ft int .Fo CMS_SignerInfo_sign .Fa "CMS_SignerInfo *si" .Fc .Sh DESCRIPTION .Fn CMS_add1_signer adds a signer with certificate .Fa signcert and private key .Fa pkey using message digest .Fa md to the .Vt CMS_ContentInfo SignedData structure .Fa cms . .Pp The .Vt CMS_ContentInfo structure should be obtained from an initial call to .Xr CMS_sign 3 with the flag .Dv CMS_PARTIAL set or in the case or re-signing a valid .Vt CMS_ContentInfo SignedData structure. .Pp If the .Fa md parameter is .Dv NULL , then the default digest for the public key algorithm will be used. .Pp Unless the .Dv CMS_REUSE_DIGEST flag is set, the returned .Vt CMS_ContentInfo structure is not complete and must be finalized either by streaming (if applicable) or a call to .Xr CMS_final 3 . .Pp The .Fn CMS_SignerInfo_sign function will explicitly sign a .Vt CMS_SignerInfo structure. Its main use is when the .Dv CMS_REUSE_DIGEST and .Dv CMS_PARTIAL flags are both set. .Pp The main purpose of .Fn CMS_add1_signer is to provide finer control over a CMS signed data structure where the simpler .Xr CMS_sign 3 function defaults are not appropriate, for example if multiple signers or non default digest algorithms are needed. New attributes can also be added using the returned .Vt CMS_SignerInfo structure and the CMS attribute utility functions or the CMS signed receipt request functions. .Pp Any of the following flags (OR'ed together) can be passed in the .Fa flags parameter: .Bl -tag -width Ds .It Dv CMS_REUSE_DIGEST Attempt to copy the content digest value from the .Vt CMS_ContentInfo structure to add a signer to an existing structure. An error occurs if a matching digest value cannot be found to copy. The returned .Vt CMS_ContentInfo structure will be valid and finalized when this flag is set. .It Dv CMS_PARTIAL If this flag is set in addition to .Dv CMS_REUSE_DIGEST , then the .Vt CMS_SignerInfo structure will not be finalized so additional attributes can be added. In this case an explicit call to .Fn CMS_SignerInfo_sign is needed to finalize it. .It Dv CMS_NOCERTS Do not include the signer's certificate in the .Vt CMS_ContentInfo structure. The signer's certificate must still be supplied in the .Fa signcert parameter though. This can reduce the size of the signature if the signer's certificate can be obtained by other means, for example from a previously signed message. .Pp The SignedData structure includes several CMS signedAttributes including the signing time, the CMS content type and the supported list of ciphers in an SMIMECapabilities attribute. .It Dv CMS_NOATTR Use no signedAttributes. .It Dv CMS_NOSMIMECAP Omit just the SMIMECapabilities. .It Dv CMS_USE_KEYID Use the subject key identifier value to identify signing certificates. An error occurs if the signing certificate does not have a subject key identifier extension. By default, issuer name and serial number are used instead. .El .Pp If present, the SMIMECapabilities attribute indicates support for the following algorithms in preference order: 256 bit AES, Gost R3411-94, Gost 28147-89, 192 bit AES, 128 bit AES, triple DES, 128 bit RC2, 64 bit RC2, DES and 40 bit RC2. If any of these algorithms is not available then it will not be included: for example the GOST algorithms will not be included if the GOST ENGINE is not loaded. .Pp .Fn CMS_add1_signer returns an internal pointer to the .Vt CMS_SignerInfo structure just added. This can be used to set additional attributes before it is finalized. .Sh RETURN VALUES .Fn CMS_add1_signer returns an internal pointer to the .Vt CMS_SignerInfo structure just added or .Dv NULL if an error occurs. .Sh SEE ALSO .Xr CMS_final 3 , .Xr CMS_sign 3 , .Xr ERR_get_error 3 .Sh HISTORY .Fn CMS_add1_signer was added to OpenSSL 0.9.8.