[#CMAC_Init]
= CMAC_Init
:mrdocs:

Initialize a CMAC context with a key and block cipher (deprecated; prefer EVP_MAC).

== Synopsis

Declared in `<openssl/cmac.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
[[deprecated]]
int
CMAC_Init(
    xref:CMAC_CTX.adoc[CMAC_CTX]* ctx,
    void const* key,
    size_t keylen,
    xref:EVP_CIPHER-07.adoc[EVP_CIPHER] const* cipher,
    xref:ENGINE.adoc[ENGINE]* impl);
----

[WARNING]
====
https://en.cppreference.com/cpp/language/attributes/deprecated[Deprecated^]. Use of this entity is allowed but discouraged.
====
== Return Value

1 on success, or 0 on failure.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *ctx*
| CMAC context to initialize.
| *key*
| CMAC key material.
| *keylen*
| Length of `key` in bytes.
| *cipher*
| Block cipher implementing CMAC (for example AES‐128‐CBC).
| *impl*
| Optional ENGINE implementing `cipher,` or NULL.
|===


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