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 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)

1.0.2g                                             2016-03-01                SSL_CTX_set_default_passwd_cb(3SSL)