DoubleThe problem with the double spend attacksproblem is not that the nodes of the network are conducted by sendersunable to independently resolve double spend attacks, those who create transactionsbut that there is no universal method that maintains consensus and can't be exploited. To resolveFor example, if they follow the rule that, of the two or more transactions in a double spend attack, someone other than the sender must answer a single question: Which transactionone with the smallest TXID is valid?, an attacker can publish the transaction with the largest TXID first then, some time later, publish the one with the smallest TXID, which then replaces the first. The purpose of a consensus protocol is to temporarily permit one node, selected at random, to make the decision for everyone else. That's what miners and forgers do when they create blocks for blockchains.

In Cosign Consensus, the same decision is made by cosignersan alternative protocol that aims to resolve double spend attacks without blockchain and POW or POS. Transactions are confirmed individually as users randomly select each other to cosign their inputs. There are no feesWhen a user creates a new transaction, and therethey need to compile a list of a hundred payment addresses selected at random from their own mempool using a verifiable random function (VRF). Once the user broadcasts their transaction, the payment addresses in it's outputs are added to the mempool so they can be selected by other users. When an output is no inflation because there is no blockchainspent, no blocksanyone on the list can sign the corresponding input, and no coinbase transactionsinclude an additional output for their fee, but the fee goes to the address with the highest priority who signs correctly. It's fully decentralized without staking or workNaturally, sonodes who want to earn as much in fees as possible are going to want to flood the mempool with addresses, to increase their odds being selected. Spam is unfair to other cosigners and it has no measurable impact onrisks compromising consensus, therefore, the environmentmax percent fee for all cosigners at any given time is equal to the number of new outputs in the mempool divided by the number of confirmed UTXOs in the global ledger. Outputs can include fee limits, and cosigners can always decide whether to cosign for lower fees and help deflate the mempool when it's grown too much.

Before a sender publishes their transaction, they need to select a cosigner for each UTXO they're spendingCosigning is optional. Nobody can be trustedis required to select a cosigner at willdo it, or they'll choose themselves or a friend, so they have to run a proof of randomness algorithm, PORA. The PORA selects a payment address at random frombut it earns fees and helps secure the pool of unconfirmed transactionsnetwork. The owners of theOnce selected addresses become the cosigners of the UTXOs being spent in the sender's transaction., a cosigner has three options:

The outputs of a transaction can't be spent until the inputs are cosigned and each output address has been used to cosign an input in another transaction. Once the sender broadcasts their transaction, the first thing they want to do is cosign something, so they wait to be selected as a cosigner. Once selected, they have three options:

• cosignsign nothing
• cosign onlysign one input, in one transaction, for the corresponding UTXOthing
• cosign every input they seesign everything

Options 1If they sign nothing or everything, they accomplish nothing and 3 are a waste of time forforfeit the cosigner because they won't unlockfee to all the other addresses on the list. The only option that earns them the fee, protects their outputs or aidwealth, and secures the network is to sign just one input, in one transaction. If a double spend attacksattack involves multiple transactions with one input, whichthe fee goes to the highest address on the list who correctly signs just one input. UTXOs are obvioussubject to everyone atchange this way until the top cosigner responds, or an output is spent. If a double spend attack involves multiple transactions, each with multiple inputs for the same set of UTXOs, the inputs should be listed by the size of the TXIDs of the UTXOs they reference in ascending order and cosigners must sign them in that pointorder to avoid signing more than one transaction. The highest address that correctly signs the first input ultimately decides which transaction is valid.

Option 2 is the only option that unlocks their coinsWith a reliable consensus protocol, protects their wealth, and securesit shouldn't be necessary to retain the networkfull history of transactions. Just keeping the previous three to five generations of transactions behind every UTXO ensures the ledger is small and portable.

(Not the same 'cosign' used in multisig) TransactionsDouble spend attacks are confirmed individually as users randomly select each other to cosign their inputs. There are no feesconducted by senders, and there is no inflation because there is no blockchain, no blocks, and no coinbasethose who create transactions. It's fully decentralizedTo resolve a double spend attack, but theresomeone other than the sender must answer a single question: Which transaction is valid? That's no work or staking, so it has no measurable impact on the environmentwhat miners and forgers do when they create blocks.

In Cosign Consensus, the same decision is made by cosigners. Transactions are confirmed individually as users randomly select each other to cosign their inputs. There are no fees, and there is no inflation because there is no blockchain, no blocks, and no coinbase transactions. It's fully decentralized without staking or work, so it has no measurable impact on the environment.

Before a sender publishes their transaction, they need to select a cosigner for each UTXO they're spending. Nobody can be trusted to select a cosigner at will, or they'll choose themselves or a friend, so they have to run a proof of randomness algorithm, PORA. The PORA selects a payment address at random from the pool of unconfirmed transactions. The owners of the selected addresses become the cosigners of the UTXOs being spent in the sender's transaction.

The outputs of a transaction can't be spent until the inputs are cosigned and each output address has been used to cosign an input in another transaction. Once the sender broadcasts their transaction, the first thing they want to do is cosign something, so they wait to be selected as a cosigner. Once selected, they have three options:

• cosign nothing
• cosign only one input, in one transaction, for the corresponding UTXO
• cosign every input they see

Options 1 and 3 are a waste of time for the cosigner because they won't unlock their outputs or aid in double spend attacks, which are obvious to everyone at that point.

Option 2 is the only option that unlocks their coins, protects their wealth, and secures the network.

(Not the same 'cosign' used in multisig) Transactions are confirmed individually as users randomly select each other to cosign their inputs. There are no fees, and there is no inflation because there is no blockchain, no blocks, and no coinbase transactions. It's fully decentralized, but there's no work or staking, so it has no measurable impact on the environment.

Before a sender publishes their transaction, they need to select a cosigner for each UTXO they're spending. Nobody can be trusted to select a cosigner at will, or they'll choose themselves or a friend, so they have to run a proof of randomness algorithm, PORA. The PORA selects a payment address at random from the pool of unconfirmed transactions. The owners of the selected addresses become the cosigners of the UTXOs being spent in the sender's transaction.

The outputs of a transaction can't be spent until the inputs are cosigned and each output address has been used to cosign an input in another transaction. Once the sender broadcasts their transaction, the first thing they want to do is cosign something, so they wait to be selected as a cosigner. Once selected, they have three options:

• cosign nothing
• cosign only one input, in one transaction, for the corresponding UTXO
• cosign every input they see

Options 1 and 3 are a waste of time for the cosigner because they won't unlock their outputs or aid in double spend attacks, which are obvious to everyone at that point.

Option 2 is the only option that unlocks their coins, protects their wealth, and secures the network.