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Command: SSL_CTX_set_default_passwd_cb | Section: 3 | Source: OpenBSD | File: SSL_CTX_set_default_passwd_cb.3
SSL_CTX_SET_DEFAULT_PASSWD_CB(3) FreeBSD Library Functions Manual
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 -
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 *userdata);
pem_password_cb *
SSL_CTX_get_default_passwd_cb(SSL_CTX *ctx);
void *
SSL_CTX_get_default_passwd_cb_userdata(SSL_CTX *ctx);
DESCRIPTION
SSL_CTX_set_default_passwd_cb() sets the password callback for loading a
certificate or private key from encrypted PEM format. In particular, the
callback is used by SSL_CTX_use_certificate_file(3),
SSL_use_certificate_file(3), SSL_CTX_use_certificate_chain_file(3),
SSL_use_certificate_chain_file(3), SSL_CTX_use_certificate_chain_mem(3),
SSL_CTX_use_PrivateKey_file(3), SSL_use_PrivateKey_file(3),
SSL_CTX_use_RSAPrivateKey_file(3), and SSL_use_RSAPrivateKey_file(3).
The function pointer type of the cb argument is documented in the
pem_password_cb(3) manual page. If SSL_CTX_set_default_passwd_cb() is
not called on ctx or if it is called with a cb argument of NULL,
PEM_def_callback(3) is used instead.
SSL_CTX_set_default_passwd_cb_userdata() sets a pointer to the userdata
which will be provided to the password callback on invocation.
Since the cb passed to SSL_CTX_set_default_passwd_cb() will only be used
for reading and decryption and not for writing and encryption, the
library will only call it with a verify argument of 0.
If an application program only needs to read and decrypt one single
private key, it can be practical to have the callback handle the password
dialog interactively. This happens by default if neither
SSL_CTX_set_default_passwd_cb() nor
SSL_CTX_set_default_passwd_cb_userdata() is called. In that case, the
library uses PEM_def_callback(3) with a userdata argument of NULL.
If several keys have to be handled, it can be practical to ask for the
password once, for example using UI_UTIL_read_pw_string(3), then keep it
in memory and use it several times by passing a pointer to it to
SSL_CTX_set_default_passwd_cb_userdata(). PEM_def_callback(3) is able to
handle this case, too, so calling SSL_CTX_set_default_passwd_cb() is not
needed in this case either.
Other items in PEM formatting (certificates) can also be encrypted; it is
however atypical, as certificate information is considered public.
RETURN VALUES
SSL_CTX_get_default_passwd_cb() returns a function pointer to the
password callback currently set in ctx, or NULL if none is set.
SSL_CTX_get_default_passwd_cb_userdata() returns a pointer to the
userdata currently set in ctx, or NULL if none is set.
EXAMPLES
The following example provides a subset of the functionality of
PEM_def_callback(3), except that PEM_def_callback(3) does not NUL-
terminate and copies up to size rather than size - 1 bytes. It
interprets userdata as a NUL-terminated string and copies it to the
password buffer, truncating the copy if it does not fit.
int
trivial_passwd_cb(char *password, int size, int verify, void *userdata)
{
strlcpy(password, userdata, size);
return strlen(password);
}
SEE ALSO
pem_password_cb(3), ssl(3), SSL_CTX_use_certificate(3)
HISTORY
SSL_CTX_set_default_passwd_cb() first appeared in SSLeay 0.6.2 and has
been available since OpenBSD 2.4.
SSL_CTX_set_default_passwd_cb_userdata() first appeared in OpenSSL 0.9.4
and has been available since OpenBSD 2.6.
SSL_CTX_get_default_passwd_cb() and
SSL_CTX_get_default_passwd_cb_userdata() first appeared in OpenSSL 1.1.0
and have been available since OpenBSD 6.3.
FreeBSD 14.1-RELEASE-p8 September 19, 2023 FreeBSD 14.1-RELEASE-p8