CoinBlesk, a Mobile NFC Bitcoin Payment System

The goal of this thesis is to design, implement, and evaluate the multisig concept with a
micro payment channel and time lock in CoinBlesk. A key feature of multisig is consumer
protection. While regular signatures in the Bitcoin network are associated with one private
key, multisig can be associated for example with three private keys, where two are required to
create a valid transaction. Currently, CoinBlesk stores per user one private key and the user
has to trust the security of the CoinBlesk server. With multisig, more than a private key is nec-
essary to create a transaction - one key can be stored on the server, the other can be with the
user - bringing back the control to the user. The time lock feature adds additional security fea-
ture to the user: if the server is offline or data is deleted, the Bitcoins from the user will be paid
to the user after the lock time expired.