ECIES<ECP> can generate a key with:
ECIES<ECP>::Decryptor decryptor(prng, ASN1::secp256r1());
Trying to generate a key outside of construction leads to a crash due to "Not Implemented" exception:
Though GenerateRandom() is being called on a DL_PrivateKeyImpl<...>, the call is being routed into DL_GroupParameters_EC<...>. Crypto++ does not implemnt curve generation and its throwing a NotImplemented exception.
The attached file duplicates the problem.