Decodes a private key from a memory buffer.
\param key a pointer to a EC_KEY object which should be used (or NULL)
\param in pointer to memory with the DER encoded private key
\param len length of the DER encoded private key
\return the decoded private key or NULL if an error occurred.
Decodes a private key from a memory buffer. \param key a pointer to a EC_KEY object which should be used (or NULL) \param in pointer to memory with the DER encoded private key \param len length of the DER encoded private key \return the decoded private key or NULL if an error occurred.