Offline Transactions in Mimblewimble
Mimblewimble is a blockchain protocol that improves on bitcoin's privacy and scalability by using pedersen commitments, schnorr signatures, and a novel technique called 'cut-through'. These benefits have come at a steep cost. Building transactions have thus far required interaction between the sender and receiver to create the outputs and collectively sign the transaction. We present here a method of achieving one-sided transactions while minimizing the impact on the scalability and privacy of mimblewimble.
Like bitcoin, Grin uses a UTXO model. Transactions are created by including inputs to spend, creating new outputs of equal or lesser value, and signing and building rangeproofs to verify ownership of the inputs.
Unlike bitcoin, Grin uses confidential transactions, so the inputs and outputs are pedersen commitments (
r*G + v*H). Instead of the signatures being added to the inputs, there is only one signature per transaction, which is part of the