/usr/man2/cat.3/SSL_CTX_set_default_passwd_cb_userdata.3.Z(/usr/man2/cat.3/SSL_CTX_set_default_passwd_cb_userdata.3.Z)

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 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 inter-
       actively. 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 impossi-
       ble.

       Other items in PEM formatting (certificates) can also be 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_user-
       data() 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                            2019-09-10  SSL_CTX_set_default_passwd_cb(3)
See also SSL_CTX_set_default_passwd_cb(3)