[#BN_rand_ex]
= BN_rand_ex
:mrdocs:

Generate a cryptographically strong public random BIGNUM with explicit strength.

== Synopsis

Declared in `<openssl/bn.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
BN_rand_ex(
    xref:BIGNUM.adoc[BIGNUM]* rnd,
    int bits,
    int top,
    int bottom,
    unsigned int strength,
    xref:BN_CTX.adoc[BN_CTX]* ctx);
----

== Return Value

1 on success, or 0 on failure.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *rnd*
| Destination BIGNUM (allocated/resized as needed).
| *bits*
| Desired bit length of the result.
| *top*
| BN_RAND_TOP_* controlling the most‐significant bits.
| *bottom*
| BN_RAND_BOTTOM_* controlling the least‐significant bit.
| *strength*
| Requested security strength in bits for the DRBG draw.
| *ctx*
| BN_CTX scratch, or NULL.
|===


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