[#EVP_PKEY_add1_attr]
= EVP&lowbar;PKEY&lowbar;add1&lowbar;attr
:mrdocs:

Append a copy of `attr` to an EVP&lowbar;PKEY attribute list, creating the list if needed&period;

== Synopsis

Declared in `&lt;openssl&sol;x509&period;h&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
EVP&lowbar;PKEY&lowbar;add1&lowbar;attr(
    xref:EVP_PKEY.adoc[EVP&lowbar;PKEY]* key,
    xref:X509_ATTRIBUTE.adoc[X509&lowbar;ATTRIBUTE]* attr);
----

== Return Value

1 on success, or 0 on failure&period;

== Parameters

[cols="1,4"]
|===
| Name| Description
| *key*
| Key whose attribute stack is updated&period;
| *attr*
| Attribute to copy onto the key&semi; must be non&hyphen;NULL and not already present&period;
|===


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