SSL_CTX_set_default_passwd_cbOpenSSL_CTX_set_default_passwd_cb(3)NAME
SSL_CTX_set_default_passwd_cb,
SSL_CTX_set_default_passwd_cb_userdata - set 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);
int pem_passwd_cb(char *buf, int size, int rwflag, void *userdata);
DESCRIPTIONSSL_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 which will be provided to the password callback
on invocation.
The pem_passwd_cb(), 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 pem_passwd_cb must write 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).
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
pem_passwd_cb() 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 pem_passwd_cb()
only returns the password already stored.
When asking for the password interactively,
pem_passwd_cb() 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 VALUESSSL_CTX_set_default_passwd_cb() and
SSL_CTX_set_default_passwd_cb_userdata() 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 pem_passwd_cb(char *buf, int size, int rwflag, void *password)
{
strncpy(buf, (char *)(password), size);
buf[size - 1] = '\0';
return(strlen(buf));
}
SEE ALSOssl(3), SSL_CTX_use_certificate(3)11/Jul/2001 0.9SSL_CTX_set_default_passwd_cb(3)
