[#PEM_def_callback]
= PEM_def_callback
:mrdocs:

Default pem_password_cb that prompts on the terminal (or copies `userdata).`

== Synopsis

Declared in `<openssl/pem.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
PEM_def_callback(
    char* buf,
    int num,
    int rwflag,
    void* userdata);
----

== Return Value

Password length written to `buf,` or 0 on failure / empty input.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *buf*
| Destination buffer for the password bytes.
| *num*
| Capacity of `buf` in bytes.
| *rwflag*
| 0 when reading/decrypting, non‐zero when writing/encrypting.
| *userdata*
| Optional default password string, or NULL to prompt.
|===


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