With this function, the caller sets the key for subsequent cipher operations.
The key must be in DER format as follows
SEQUENCE { version INTEGER, n INTEGER ({ rsa_get_n }), e INTEGER ({ rsa_get_e }), d INTEGER ({ rsa_get_d
}), prime1 INTEGER, prime2 INTEGER, exponent1 INTEGER, exponent2 INTEGER, coefficient INTEGER }
After the caller provided the key, the caller may securely destroy the key as it is now maintained by the
kernel.
return upon success the value of the maximum size for the asymmetric operation is returned (e.g. the
modulus size); a negative errno-style error code if an error occurred