[#EVP_PKEY_CTX_new_from_pkey]
= EVP_PKEY_CTX_new_from_pkey
:mrdocs:

Allocate a key context for operations on an existing EVP_PKEY.

== Synopsis

Declared in `<openssl/evp.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:EVP_PKEY_CTX.adoc[EVP_PKEY_CTX]*
EVP_PKEY_CTX_new_from_pkey(
    xref:OSSL_LIB_CTX.adoc[OSSL_LIB_CTX]* libctx,
    xref:EVP_PKEY.adoc[EVP_PKEY]* pkey,
    char const* propquery);
----

== Return Value

New EVP_PKEY_CTX, or NULL on failure.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *libctx*
| Library context used to fetch algorithms, or NULL for the default.
| *pkey*
| Key that determines the algorithm and provides key material.
| *propquery*
| Property query for algorithm fetches, or NULL.
|===


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