[#CMS_SharedInfo_encode]
= CMS_SharedInfo_encode
:mrdocs:

DER‐encode a CMS SharedInfo structure used in key‐encryption key derivation.

== Synopsis

Declared in `<openssl/cms.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
CMS_SharedInfo_encode(
    unsigned char** pder,
    xref:X509_ALGOR.adoc[X509_ALGOR]* kekalg,
    xref:ASN1_OCTET_STRING.adoc[ASN1_OCTET_STRING]* ukm,
    int keylen);
----

== Return Value

Length of the DER encoding, or a negative value on error.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *pder*
| Receives a newly allocated DER encoding on success; free with OPENSSL_free.
| *kekalg*
| Key‐encryption algorithm identifier placed in SharedInfo.
| *ukm*
| Optional user keying material OCTET STRING, or NULL.
| *keylen*
| Length in bytes of the KEK being derived (encoded as a 4‐byte INTEGER).
|===


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