[#ECDH_KDF_X9_62]
= ECDH_KDF_X9_62
:mrdocs:

Derive key material from an ECDH shared secret using the X9.63 KDF (deprecated).

== Synopsis

Declared in `<openssl/ec.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
[[deprecated]]
int
ECDH_KDF_X9_62(
    unsigned char* out,
    size_t outlen,
    unsigned char const* Z,
    size_t Zlen,
    unsigned char const* sinfo,
    size_t sinfolen,
    xref:EVP_MD.adoc[EVP_MD] const* md);
----

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

Historically named for ANSI X9.62; the KDF is actually specified in ANSI X9.63. Retained for ABI compatibility (prefer X9.63‐named APIs).

== Return Value

1 on success, or 0 on failure.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *out*
| Destination buffer for the derived key material.
| *outlen*
| Number of bytes to write to `out.`
| *Z*
| Shared secret (ECDH Z) octets used as KDF key input.
| *Zlen*
| Length of `Z` in bytes.
| *sinfo*
| Optional shared‐info / OtherInfo octets bound into the KDF, or NULL if `sinfolen` is 0.
| *sinfolen*
| Length of `sinfo` in bytes.
| *md*
| Message digest used by the X9.63 KDF (for example SHA‐256).
|===


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