[#BN_is_prime]
= BN_is_prime
:mrdocs:

Probable‐primality test without trial division (deprecated; prefer BN_check_prime()).

== Synopsis

Declared in `<openssl/bn.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
[[deprecated]]
int
BN_is_prime(
    xref:BIGNUM.adoc[BIGNUM] const* p,
    int nchecks,
    void(* callback)(int, int, void*),
    xref:BN_CTX.adoc[BN_CTX]* ctx,
    void* cb_arg);
----

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

1 if probably prime, 0 if composite, or ‐1 on error.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *p*
| Candidate integer.
| *nchecks*
| Number of Miller‐Rabin rounds (or BN_prime_checks for a size‐based default).
| *callback*
| Optional old‐style progress callback, or NULL.
| *ctx*
| BN_CTX for temporaries, or NULL.
| *cb_arg*
| User pointer passed to `callback.`
|===


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