[#EVP_PKEY_CTX_md]
= EVP_PKEY_CTX_md
:mrdocs:

Set a digest algorithm on a key context by name for the given operation.

== Synopsis

Declared in `<openssl/evp.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
EVP_PKEY_CTX_md(
    xref:EVP_PKEY_CTX.adoc[EVP_PKEY_CTX]* ctx,
    int optype,
    int cmd,
    char const* md);
----

== Return Value

Positive value on success, or a non‐positive value on failure.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *ctx*
| Key context to update.
| *optype*
| Operation type such as EVP_PKEY_OP_TYPE_SIG.
| *cmd*
| Control command that expects an EVP_MD (for example EVP_PKEY_CTRL_MD).
| *md*
| Digest name such as "SHA256".
|===


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