[#EVP_KDF_derive]
= EVP_KDF_derive
:mrdocs:

Derive keying material into `key` using the parameters bound to `ctx.`

== Synopsis

Declared in `<openssl/kdf.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
EVP_KDF_derive(
    xref:EVP_KDF_CTX.adoc[EVP_KDF_CTX]* ctx,
    unsigned char* key,
    size_t keylen,
    xref:OSSL_PARAM.adoc[OSSL_PARAM] const params[]);
----

== Return Value

1 on success, or 0 on failure.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *ctx*
| Initialized KDF context.
| *key*
| Output buffer for the derived key.
| *keylen*
| Number of bytes to write to `key.`
| *params*
| Optional additional OSSL_PARAM array, or NULL.
|===


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