Sets the key method data of an EC_KEY object, if none has yet been set.
EC_KEY object
opaque data to install.
a function that duplicates |data|.
a function that frees |data|.
a function that wipes and frees |data|.
the previously set data pointer, or null if |data| was inserted.
See Implementation
Sets the key method data of an EC_KEY object, if none has yet been set.