/xlv3/openssl/0.9.7e-sgipl1/work/0.9.7e-sgipl1/openssl-
0.9.7e/doc/ssl
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SSL_CTX_set_default_pas11/Jul/200SSL_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);
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 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
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encrypted, it is however not usual, as certificate
information is considered public.
RETURN VALUES
SSL_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 ALSO
ssl(3), SSL_CTX_use_certificate(3)
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