[#CMS_add1_signer]
= CMS_add1_signer
:mrdocs:

Add a signer certificate and private key to a CMS SignedData ContentInfo.

== Synopsis

Declared in `<openssl/cms.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:CMS_SignerInfo.adoc[CMS_SignerInfo]*
CMS_add1_signer(
    xref:CMS_ContentInfo.adoc[CMS_ContentInfo]* cms,
    xref:X509.adoc[X509]* signer,
    xref:EVP_PKEY.adoc[EVP_PKEY]* pk,
    xref:EVP_MD.adoc[EVP_MD] const* md,
    unsigned int flags);
----

== Description

Unless CMS_REUSE_DIGEST is set, the ContentInfo is incomplete until finalized by streaming or CMS_final().

== Return Value

The new CMS_SignerInfo on success, or NULL on error.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *cms*
| CMS_ContentInfo that must already be SignedData (for example from CMS_sign() with CMS_PARTIAL).
| *signer*
| Signer certificate.
| *pk*
| Private key corresponding to `signer.`
| *md*
| Message digest to use, or NULL to select the default digest for the key algorithm.
| *flags*
| CMS_* option flags controlling digest reuse, attributes, and finalization.
|===


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