  Quantum randomness relies heavily on the accurate characterization of the
generator implementation, where the device imperfection or inaccurate
characterization can lead to incorrect entropy estimation and practical bias,
significantly affecting the reliability of the generated randomness.
Measurement-device-independent (MDI) quantum random number generation (QRNG)
endeavors to produce certified randomness, utilizing uncharacterized and
untrusted measurement devices that are vulnerable to numerous attack schemes
targeting measurement loopholes. However, existing implementations have shown
insufficient performance thus far. Here, we propose a high-speed MDI-QRNG
scheme based on a robust measurement tomography approach against the
imperfection of single-photon sources. Compared with the conventional approach,
the decoy-state method is introduced to obtain more accurate tomography results
and a tighter lower bound of randomness. Finally, by using a high-speed
time-bin encoding system, we experimentally demonstrated the scheme and
obtained a reliable min-entropy lower bound of $7.37 \times 10^{-2}$ bits per
pulse, corresponding to a generation rate over 23 Mbps, which substantially
outperforms the existing realizations and makes a record in discrete-variable
semi-device-independent QRNGs.
