  The information reconciliation in a quantum key distribution protocol can be
studied separately from other steps in the protocol. The problem of information
reconciliation can be reduced to that of distributed source coding. Its
solution by LDPC codes is reviewed. We list some obstacles preventing the
LDPC-based distributed source coding from becoming a more favorable alternative
to the Cascade protocol for information reconciliation in quantum key
distribution protocols. This exposition does not require knowledge of the
quantum theory.
