[#EVP_PKEY_CTX_ctrl]
= EVP_PKEY_CTX_ctrl
:mrdocs:

Send an algorithm‐specific control command to a key context.

== Synopsis

Declared in `<openssl/evp.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
EVP_PKEY_CTX_ctrl(
    xref:EVP_PKEY_CTX.adoc[EVP_PKEY_CTX]* ctx,
    int keytype,
    int optype,
    int cmd,
    int p1,
    void* p2);
----

== Return Value

Positive on success, 0 or negative on failure.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *ctx*
| Key context receiving the command.
| *keytype*
| Expected key type, or ‐1 to skip the type check.
| *optype*
| Expected operation type, or ‐1 to skip the operation check.
| *cmd*
| Algorithm‐specific control command.
| *p1*
| Integer argument for `cmd.`
| *p2*
| Pointer argument for `cmd,` or NULL.
|===


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