SSL_CTX_SET_DEFAULT_P... BSD Library Functions Manual SSL_CTX_SET_DEFAULT_P...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 u
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 writ‐
ing/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 interac‐
tively. 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 compari‐
son in order to catch typos which would make decryption impossible.
Other items in PEM formatting (certificates) can also be encrypted; it is
however atypical, 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 infor‐
mation.
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)BSD April 25, 2024 BSD
