1=pod
2
3=head1 NAME
4
5SSL_CTX_set_default_passwd_cb, SSL_CTX_set_default_passwd_cb_userdata,
6SSL_CTX_get_default_passwd_cb, SSL_CTX_get_default_passwd_cb_userdata,
7SSL_set_default_passwd_cb, SSL_set_default_passwd_cb_userdata,
8SSL_get_default_passwd_cb, SSL_get_default_passwd_cb_userdata - set or
9get passwd callback for encrypted PEM file handling
10
11=head1 SYNOPSIS
12
13 #include <openssl/ssl.h>
14
15 void SSL_CTX_set_default_passwd_cb(SSL_CTX *ctx, pem_password_cb *cb);
16 void SSL_CTX_set_default_passwd_cb_userdata(SSL_CTX *ctx, void *u);
17 pem_password_cb *SSL_CTX_get_default_passwd_cb(SSL_CTX *ctx);
18 void *SSL_CTX_get_default_passwd_cb_userdata(SSL_CTX *ctx);
19
20 void SSL_set_default_passwd_cb(SSL *s, pem_password_cb *cb);
21 void SSL_set_default_passwd_cb_userdata(SSL *s, void *u);
22 pem_password_cb *SSL_get_default_passwd_cb(SSL *s);
23 void *SSL_get_default_passwd_cb_userdata(SSL *s);
24
25=head1 DESCRIPTION
26
27SSL_CTX_set_default_passwd_cb() sets the default password callback called
28when loading/storing a PEM certificate with encryption.
29
30SSL_CTX_set_default_passwd_cb_userdata() sets a pointer to userdata, B<u>,
31which will be provided to the password callback on invocation.
32
33SSL_CTX_get_default_passwd_cb() returns a function pointer to the password
34callback currently set in B<ctx>. If no callback was explicitly set, the
35NULL pointer is returned.
36
37SSL_CTX_get_default_passwd_cb_userdata() returns a pointer to the userdata
38currently set in B<ctx>. If no userdata was explicitly set, the NULL pointer
39is returned.
40
41SSL_set_default_passwd_cb(), SSL_set_default_passwd_cb_userdata(),
42SSL_get_default_passwd_cb() and SSL_get_default_passwd_cb_userdata() perform
43the same function as their SSL_CTX counterparts, but using an SSL object.
44
45The password callback, which must be provided by the application, hands back the
46password to be used during decryption.
47On invocation a pointer to userdata
48is provided. The function must store the password into the provided buffer
49B<buf> which is of size B<size>. The actual length of the password must
50be returned to the calling function. B<rwflag> indicates whether the
51callback is used for reading/decryption (rwflag=0) or writing/encryption
52(rwflag=1).
53For more details, see L<pem_password_cb(3)>.
54
55=head1 NOTES
56
57When loading or storing private keys, a password might be supplied to
58protect the private key. The way this password can be supplied may depend
59on the application. If only one private key is handled, it can be practical
60to have the callback handle the password dialog interactively. If several
61keys have to be handled, it can be practical to ask for the password once,
62then keep it in memory and use it several times. In the last case, the
63password could be stored into the userdata storage and the
64callback only returns the password already stored.
65
66When asking for the password interactively, the callback can use
67B<rwflag> to check, whether an item shall be encrypted (rwflag=1).
68In this case the password dialog may ask for the same password twice
69for comparison in order to catch typos, that would make decryption
70impossible.
71
72Other items in PEM formatting (certificates) can also be encrypted, it is
73however not usual, as certificate information is considered public.
74
75=head1 RETURN VALUES
76
77These functions do not provide diagnostic information.
78
79=head1 EXAMPLES
80
81The following example returns the password provided as userdata to the
82calling function. The password is considered to be a '\0' terminated
83string. If the password does not fit into the buffer, the password is
84truncated.
85
86 int my_cb(char *buf, int size, int rwflag, void *u)
87 {
88     strncpy(buf, (char *)u, size);
89     buf[size - 1] = '\0';
90     return strlen(buf);
91 }
92
93=head1 SEE ALSO
94
95L<ssl(7)>,
96L<SSL_CTX_use_certificate(3)>
97
98=head1 HISTORY
99
100SSL_CTX_get_default_passwd_cb(), SSL_CTX_get_default_passwd_cb_userdata(),
101SSL_set_default_passwd_cb() and SSL_set_default_passwd_cb_userdata() were
102added in OpenSSL 1.1.0.
103
104=head1 COPYRIGHT
105
106Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
107
108Licensed under the Apache License 2.0 (the "License").  You may not use
109this file except in compliance with the License.  You can obtain a copy
110in the file LICENSE in the source distribution or at
111L<https://www.openssl.org/source/license.html>.
112
113=cut
114