[#EC_GROUP_check_named_curve]
= EC_GROUP_check_named_curve
:mrdocs:

Identify whether `group` matches a built‐in named curve and return its NID.

== Synopsis

Declared in `<openssl/ec.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
EC_GROUP_check_named_curve(
    xref:EC_GROUP.adoc[EC_GROUP] const* group,
    int nist_only,
    xref:BN_CTX.adoc[BN_CTX]* ctx);
----

== Return Value

Matching curve NID on success, or 0 / a negative value when no named curve matches or on error.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *group*
| Curve group to compare against known named curves.
| *nist_only*
| When non‐zero, only NIST curves are considered.
| *ctx*
| Optional BN_CTX for temporary big‐number work, or NULL.
|===


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