  In this paper, we propose a two-party semiquantum summation protocol, where
two classical users can accomplish the summation of their private binary
sequences with the assistance of a quantum semi-honest third party (TP). The
term 'semi-honest' implies that TP cannot conspire with others but is able to
implement all kinds oof attacks. This protocol employs logical qubits as
traveling particles to overcome the negative influence of collective-dephasing
noise and needn't make any two parties pre-share a random secret key. The
security analysis turns out that this protocol can effectively prevent the
outside attacks from Eve and the participant attacks from TP. Moreover, TP has
no knowledge about the summation results.
