  In this work, we propose a stateless blockchain called CompactChain, which
compacts the entire state of the UTXO (Unspent Transaction Output) based
blockchain systems into two RSA accumulators. The first accumulator is called
Transaction Output (TXO) commitment which represents the TXO set. The second
one is called Spent Transaction Output (STXO) commitment which represents the
STXO set. In this work, we discuss three algorithms - (i) To update the TXO and
STXO commitments by the miner. The miner also provides the proofs for the
correctness of the updated commitments; (ii) To prove the transaction's
validity by providing a membership witness in TXO commitment and non-membership
witness against STXO commitment for a coin being spent by a user; (iii) To
update the witness for the coin that is not yet spent; The experimental results
evaluate the performance of the CompactChain in terms of time taken by a miner
to update the commitments and time taken by a validator to verify the
commitments and validate the transactions. We compare the performance of
CompactChain with the existing state-of-art works on stateless blockchains.
CompactChain shows a reduction in commitments update complexity and transaction
witness size which inturn reduces the mempool size and propagation latency
without compromising the system throughput (Transactions per second (TPS)).
