  Digital signatures play an important role in software distribution, modern
communication and financial transactions, where it is important to detect
forgery and tampering. Signatures are a cryptographic technique for validating
the authenticity and integrity of messages, software, or digital documents. The
security of currently used classical schemes relies on computational
assumptions. Quantum digital signatures (QDS), on the other hand, provide
information-theoretic security based on the laws of quantum physics. Recent
work on QDS shows that such schemes do not require trusted quantum channels and
are unconditionally secure against general coherent attacks. However, in
practical QDS, just as in quantum key distribution (QKD), the detectors can be
subjected to side-channel attacks, which can make the actual implementations
insecure. Motivated by the idea of measurement-device-independent quantum key
distribution (MDI-QKD), we present a measurement-device-independent QDS
(MDI-QDS) scheme, which is secure against all detector side-channel attacks.
Based on the rapid development of practical MDI-QKD, our MDI-QDS protocol could
also be experimentally implemented, since it requires a similar experimental
setup.
