Revisiting the Security and Efficiency of Sp2das, 3pda, and Eppa Smart Grid Security Protocols

This paper analyses the security and efficiency of some notable privacy preserving data aggregation schemes, sp2das, 3pda, and eppa. for sp2das and 3pda schemes, we show that despite the designers' claims, there are eficient forgery attacks on the signature scheme used. we present a selective forgery attack on the signature scheme of sp2das in the key-only attack model and a selective forgery attack on the 3pda's signature scheme in the known-message attack model, requiring only two pairs of message-signature. these attacks enable the attacker to inject any arbitrary faulty data into the data aggregated by the network, without being detected, which is a serious threat to the performance of the whole network. we also present an improved version of the broadcast encryption scheme used in eppa scheme, in which the decryption key is half, the decryption complexity is half, and the ciphertext size is 3=4 of the original one. the semantic security of the proposed scheme is proved under the same assumption as the original scheme.