NAME

       SSL_CTX_set_default_passwd_cb, SSL_CTX_set_default_passwd_cb_userdata,
       SSL_CTX_get_default_passwd_cb, SSL_CTX_get_default_passwd_cb_userdata,
       SSL_set_default_passwd_cb, SSL_set_default_passwd_cb_userdata, SSL_get_default_passwd_cb,
       SSL_get_default_passwd_cb_userdata - set or get passwd callback for encrypted PEM file
       handling

SYNOPSIS

        #include <openssl/ssl.h>

        void SSL_CTX_set_default_passwd_cb(SSL_CTX *ctx, pem_password_cb *cb);
        void SSL_CTX_set_default_passwd_cb_userdata(SSL_CTX *ctx, void *u);
        pem_password_cb *SSL_CTX_get_default_passwd_cb(SSL_CTX *ctx);
        void *SSL_CTX_get_default_passwd_cb_userdata(SSL_CTX *ctx);

        void SSL_set_default_passwd_cb(SSL *s, pem_password_cb *cb);
        void SSL_set_default_passwd_cb_userdata(SSL *s, void *u);
        pem_password_cb *SSL_get_default_passwd_cb(SSL *s);
        void *SSL_get_default_passwd_cb_userdata(SSL *s);

DESCRIPTION

       SSL_CTX_set_default_passwd_cb() sets the default password callback called when
       loading/storing a PEM certificate with encryption.

       SSL_CTX_set_default_passwd_cb_userdata() sets a pointer to userdata, u, which will be
       provided to the password callback on invocation.

       SSL_CTX_get_default_passwd_cb() returns a function pointer to the password callback
       currently set in ctx. If no callback was explicitly set, the NULL pointer is returned.

       SSL_CTX_get_default_passwd_cb_userdata() returns a pointer to the userdata currently set
       in ctx. If no userdata was explicitly set, the NULL pointer is returned.

       SSL_set_default_passwd_cb(), SSL_set_default_passwd_cb_userdata(),
       SSL_get_default_passwd_cb() and SSL_get_default_passwd_cb_userdata() perform the same
       function as their SSL_CTX counterparts, but using an SSL object.

       The password callback, which must be provided by the application, hands back the password
       to be used during decryption.  On invocation a pointer to userdata is provided. The
       function must store the password into the provided buffer buf which is of size size. The
       actual length of the password must be returned to the calling function. rwflag indicates
       whether the callback is used for reading/decryption (rwflag=0) or writing/encryption
       (rwflag=1).  For more details, see pem_password_cb(3).

NOTES

       When loading or storing private keys, a password might be supplied to protect the private
       key. The way this password can be supplied may depend on the application. If only one
       private key is handled, it can be practical to have the callback handle the password
       dialog interactively. If several keys have to be handled, it can be practical to ask for
       the password once, then keep it in memory and use it several times. In the last case, the
       password could be stored into the userdata storage and the callback only returns the
       password already stored.

       When asking for the password interactively, the callback can use rwflag to check, whether
       an item shall be encrypted (rwflag=1).  In this case the password dialog may ask for the
       same password twice for comparison in order to catch typos, that would make decryption
       impossible.

       Other items in PEM formatting (certificates) can also be encrypted, it is however not
       usual, as certificate information is considered public.

RETURN VALUES

       These functions do not provide diagnostic information.

EXAMPLES

       The following example returns the password provided as userdata to the calling function.
       The password is considered to be a '\0' terminated string. If the password does not fit
       into the buffer, the password is truncated.

        int my_cb(char *buf, int size, int rwflag, void *u)
        {
            strncpy(buf, (char *)u, size);
            buf[size - 1] = '\0';
            return strlen(buf);
        }

SEE ALSO

       ssl(7), SSL_CTX_use_certificate(3)

HISTORY

       SSL_CTX_get_default_passwd_cb(), SSL_CTX_get_default_passwd_cb_userdata(),
       SSL_set_default_passwd_cb() and SSL_set_default_passwd_cb_userdata() were added in OpenSSL
       1.1.0.

COPYRIGHT

       Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (the "License").  You may not use this file except
       in compliance with the License.  You can obtain a copy in the file LICENSE in the source
       distribution or at <https://www.openssl.org/source/license.html>.