  We provide a security analysis of continuous-variable quantum key
distribution (CVQKD) with discrete modulation against general attacks in a
realistic finite-size regime. To realize this goal, we first prove security of
the continuous-variable quantum key distribution protocol with discrete
modulation against collective attacks by using the reliable tomography of the
covariance matrix, leading to the reliable and tight error bounds in the
derived confidence regions. Combining the proof with de Finetti reduction, the
discrete-modulation-based continuous-variable quantum key distribution
(DM-CVQKD) is proved to be secure even exposing to general attacks. Specially,
we use an energy test to truncate the Hilbert space globally to provide
security.
