In traditional PoS cryptos, the UTXO (Unspent Transaction Output) is used in the staking calculation. In Alias APoS we use the so-called ‘keyimage’ associated with an ATXO (Anonymous Transaction Output) instead as an input in the staking calculations for private balances. An ATXO is associated with a discreet private-ALIAS value and has a unique cryptographically determined ‘keyimage’ associated with it. APoS offers a through-and-through confidential way to maintain consensus and provide strong privacy for participants whilst securing the network. It is also appropriate to emphasise that APoS is entirely decentralised. APoS does not depend on any central servers or authority and is 100% peer-to-peer. There has never been any trusted setup. APoS provides robust network resilience with no single point of failure whilst providing outstanding privacy for users.

Stealth Address techniques allow public keys appearing in the blockchain to be fully disconnected from so-called “stealth” public keys which can be published by a payee. The public “stealth” keys published serve as a “master public key” from which “ephemeral public keys” are derived. The “stealth” public key is never recorded in the blockchain. This enables the payee to receive infinite un-linkable payments by publishing only one stealth address. This negates some of the most common ways of deanonymizing transactions on a public blockchain.

There must be an ample supply of unspent ATXO decoys for inclusion into the ring-signatures to achieve consistent anonymity. If an ATXO is staked, the algorithm searches for the denomination with the least amount of unspent ATXOs within a range of values. Suppose a denomination in this range is found with less than 100 unspent ATXOs. In that case, the staked ATXO will be split to create one ATXO of the”low running” denomination. Also, through the APoS process and in any anonymous transactions (private-to-private ALIAS transactions), there will be constant creation of small value ATXOs from staking rewards and transaction change. This will tend to result in larger transaction sizes in subsequent transactions as the number of smaller value ATXOs are combined for the desired output amount. Alias solves this problem via an ATXO consolidation algorithm, as part of the ATXO staking transaction where same value ATXOs are consolidated into larger value ATXOs. The ‘consolidation algorithm‘ then tries to consolidate up to 50 ATXOs. These two algorithms achieve the right balance and supply of decoys while maximising performance.

In a private transaction, the sender could own any one of the ten ATXOs used in the ring-signature. An adversary cannot determine which of the 10 ATXOs included in the ring-signature is being spent. Decoy ATXOs called ‘mixins‘ are at the core of ring-signature privacy, and it is paramount that the software can pick the right decoys. An unusual situation could occur where all the mixins available for a specific denomination become spent except for the sender’s ATXOs to be spent in the transaction. This situation could compromise the anonymity of the transaction and the mixins, although these circumstances are improbable. Furthermore, all the ATXOs created in the same transaction are part of an ‘ATXO Set‘. Those ATXOs will forever be linked to each other as they were created at the same time. There will always be multiple outputs in any transaction because amounts have to be split into discrete values. This could lead to a situation where the mixins in a ring-signature originate from the same ‘ATXO set‘. This could conceivably compromise anonymity by making the ring-signatures more susceptible to deductive analysis. In other words, an adversary might be able to determine which of the mixins are fake. Therefore, these situations cannot be allowed to occur. Alias solved these issues by incorporating specific ‘smart mixin picking‘ algorithms to maximise the anonymity of private transactions.