[#EVP_MAC_update]
= EVP_MAC_update
:mrdocs:

Feed more message bytes into a MAC computation.

== Synopsis

Declared in `<openssl/evp.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
EVP_MAC_update(
    xref:EVP_MAC_CTX.adoc[EVP_MAC_CTX]* ctx,
    unsigned char const* data,
    size_t datalen);
----

== Return Value

1 on success, or 0 on failure.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *ctx*
| MAC context previously initialised with EVP_MAC_init().
| *data*
| Message bytes to absorb.
| *datalen*
| Number of bytes at `data.`
|===


[.small]#Created with https://www.mrdocs.com[MrDocs]#