Updated: 2021/Apr/14

SSL_CTX_set_default_passwd_cb(3)    OpenSSL   SSL_CTX_set_default_passwd_cb(3)

       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

       libcrypto, -lcrypto

        #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);

       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

       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.

       These functions do not provide diagnostic information.

       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

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

       ssl(7), SSL_CTX_use_certificate(3)

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

       Licensed under the OpenSSL license (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

1.1.1i                            2019-06-09  SSL_CTX_set_default_passwd_cb(3)