/usr/man/cat.3/SSL_CTX_set_default_passwd_cb.3

SSL_CTX_set_default_passwd_cb(3OpenSSSSL_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
     encrypted, it is however not usual, as certificate

1.0.2t               Last change: 2019-09-10                    1

SSL_CTX_set_default_passwd_cb(3OpenSSSSL_CTX_set_default_passwd_cb(3)

     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)

1.0.2t               Last change: 2019-09-10                    2

See also SSL_CTX_set_default_passwd_cb_userdata(3)