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.

       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_userdata() do not provide
       diagnostic information.

       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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