Print Page - [ANN] Stegos: Like MimbleWimble but with PoS

Visit our website (https://stegos.com) and join our Telegram community (https://t.me/stegos4privacy) to discuss the whitepaper (https://github.com/stegos/stegos/wiki).

Summary

The Stegos Privacy Blockchain (Stegos) and tokens implement a completely private, confidential, and scalable cryptocurrency that’s secure, efficient, and friendly to the environment.

Other privacy tokens — such as Monero, Dash, ZCash, and Grin — can only send anonymous and private payments. Stegos builds and improves upon other privacy coins and can be used to send both payments and data with complete confidentiality. The Stegos Privacy Platform can be used to build applications that community anonymously, privately and efficiently.

Transactions in Stegos are unlinkable, untraceable, and completely confidential. Stegos makes it impossible to identify recipients of a transaction because each transaction is directed to a new and unique address.

Stegos makes it impossible to trace transaction histories since many individual transactions are joined together to form a super-transaction. This is done in a secure and privacy-preserving way, before submitting the transaction to blockchain validators. Stegos coins are fully fungible!

All amounts in Stegos are hidden using cryptographic commitments and zero-knowledge proofs. Validator stakes and transaction fees are the only exception, since these must be visible for blockchain validation.

Stegos is a fast and highly scalable blockchain and, unlike other blockchains, it’s kept small. Spent coins and consumed data are safely removed from the blockchain using secure cryptographic pruning. This breakthrough lets Stegos run on billions of mobile devices, for a truly decentralized blockchain. Stegos is the first and only blockchain that can run in your pocket!

Stegos uses transactional sharding to scale. Separate groups of Stegos validators keep the whole blockchain state but verify only a subset of incoming transactions, using cross-shard atomic commits to eliminate double-spending. This scalability approach lets Stegos process hundreds of thousands of transactions per second.

Stegos is environmentally friendly and does not require megawatts of electricity to be spent mining blocks. Stegos uses PoS (proof of stake) consensus, building on advancements in distributed systems theory and cryptography. Each new Stegos block must be verified and confirmed by a group of validators, all of whom must put tokens in escrow as their stake.

The value of the tokens staked has a direct effect on the probability of a validator to win a block and earn transaction fees. Stegos does not have block rewards, instead replacing them with the Jackpot.

This feature is unique to Stegos, based on a familiar lottery concept. A portion of the fees from each block are added to the jackpot, along with any stake forfeited by a validator caught cheating.

The jackpot is distributed every few thousand blocks when validators run a cryptographic lottery based on verifiable distributed randomness. The amount in the jackpot is then transferred to the winner. The longer a validator keeps their stake and participates in consensus, the higher their probability of winning the jackpot lottery!

No ICO

Stegos will not hold an ICO. STG, the native token, will be available once the mainnet is launched. The STG token will be privately sold to high net-worth individuals and companies. When posted as collateral by nodes wishing to support the Stegos platform, the STG token gives the right to earn block rewards and fees.

Funding

Stegos will generate a pre-mine of 1 billion STG tokens. Up to 51.25% of the STG pre-mine may be privately sold to reach a maximum of of $30M (million). Stegos has already raised $15M (million) of this target in 2018. Once the mainnet is launched, STG tokens will be sold directly to the general public using the built-in DEX.

Monetary Policy

STG token emission and block reward rate will start at 14% during the first 4 years and halve every 4 years thereafter.

Stegos vs MimbleWimble

MimbleWimble is a blockchain format and protocol that provides extremely good scalability, privacy and fungibility by relying on strong cryptographic primitives.

Stegos started life by implementing MimbleWimble. Unfortunately, the receiver of the payment needs to be online for the security features of MimbleWimble to work. The current implementations of MimbleWimble, e.g. Grin and Beam also require you to communicate out of band, potentially compromising security. Both of these restrictions were a non-starter for us and our current design removes them.

Untraceability, preventing adversaries from tracing coins from inputs to outputs, is what makes cryptocurrency fungible, i.e. coins are equal and there are no tainted coins. Unfortunately, MimbleWimble (Grin and Beam) only partially support untraceability by removing transaction boundaries when composing and sealing a block. It’s still possible to implant a node on the MimbleWimble network and record all transactions related to a block, thus enabling adversaries to track funds and taint coins.

Stegos implements full untraceability, with a DiceMix-based protocol that mixes inputs and outputs from many users willing to post transactions. This protocol creates a super-transaction that severs the link from inputs and outputs. Only the supertransaction is sent to the network so validators, including any adversaries listening in, do not have the ability to trace funds by connecting transaction inputs with outputs.

Technical Overview

Following is a brief technical summary, with more detail available in our Technical Paper (https://stegos.com/docs/yellowpaper.pdf).

UTXO and Proof-of-Stake

Stegos uses the UTXO, or unspent transaction outputs model, and PoS (Proof-of-Stake) consensus. PoS allows Stegos to achieve a higher throughput over Proof-of-Work (PoW) systems, at significantly lower energy costs. Stegos is friendly to the environment and does not require megawatts of electricity to be spent on mining blocks.

UTXO was first introduced by Bitcoin and, unlike the Ethereum account-based model, aggregates spent and unspent coins, available across multiple wallets, into a single balance. Not only does UTXO offer simplicity, it also drastically increases the Stegos scaling capability, by enabling transactions to be processed independently and in parallel.

Each new Stegos block must be verified and confirmed by a group of validators, all of which must put tokens in escrow (stake). The size of the tokens staked has a direct effect on the probability of a validator to win a block and earn block rewards and transaction fees.

Transactions and Non-Interactive Zero-Knowledge Proofs

Transactions in Stegos are unlinkable, untraceable, and completely confidential. Stegos makes it impossible to identify recipients of a transaction because transactions are directed to new and unique addresses.

Stegos makes it impossible to trace the history of transactions since many individual transactions are joined together to form a super-transaction. This is done in a secure and privacy-preserving way, before submitting the transaction to blockchain validators. Stegos Privacy Coins are fully fungible.

Zero-knowledge proofs are the Stegos privacy pillar. Stegos uses zero-knowledge proofs to ensure transaction amounts, among other things, are not visible in the public ledger. For example, although blockchain addresses are represented by random strings, it is currently possible for mapping software to crawl Bitcoin’s ledger for spent and unspent (UTXO) coins, to identify the transactions of a single private key and determine a holder’s total wealth in Bitcoin.

While non-interactive zero-knowledge proofs do not prevent such transaction graph analyses, they prevent the tracing party from seeing the amounts being transferred. All amounts in Stegos are hidden using cryptographic (Pedersen) commitments and zero-knowledge range proofs (Bulletproofs). Validator stakes and transaction fees are the only exception since these must be visible for blockchain validation.

Pooled transactions

Stegos implements a peer-to-peer transaction mixing mechanism based on ValueShuffle. This mechanism combines Stealth Addresses to protect recipient's anonymity, Pedersen Commitments and Bulletproofs to cloak transaction values, as well as CoinJoin to make transactions untraceable. We also employ DiceMix (which relies on Dining Cryptographers networks or DC-nets) to ensure sender's anonymity and make it impossible for an attacker to associate a message with its sender.

Scalability and Compaction

Many projects claim to be able to process a million transactions per second (TPS), but none of them explain how they will maintain all the accumulated data. Bitcoin provides for 7-10 TPS and the Bitcoin blockchain is expected to grow past 170 terabytes by the end of 2018. If we assume that Bitcoin suddenly supports 16,000 TPS, the Bitcoin blockchain will grow by 350 gigabytes every day, or 127 terabytes every year. This amount of data is completely unsustainable unless the blockchain is centralized on a few supercomputers, something that’s contrary to blockchain’s decentralization ethos.

Stegos is a fast and highly scalable blockchain that, unlike other blockchains, is kept small. Spent coins and consumed data are safely removed from the blockchain using secure cryptographic pruning. This breakthrough enables Stegos to run on billions of mobile devices, for a truly decentralized blockchain. Stegos is the first and only blockchain that can run in your pocket.

Stegos uses transactional sharding to scale. Separate groups of Stegos validators keep the whole blockchain state but verify only a subset of incoming transactions, using cross-shard atomic commits to eliminate double spending. This scaling approach lets Stegos process hundreds of thousands of transactions per second.

Expanding the Ecosystem

Stegos aims to build an ecosystem, with applications from different developers running on the Stegos Privacy Blockchain and protecting our privacy. Stegos will build libraries and software development kits (SDKs) to help build applications and make them available to the community. Stegos will use the same libraries and SDKs to build its own applications.

Stegos will also introduce an App Store for privacy applications.

Visit our website (https://stegos.com) and join our Telegram community (https://t.me/stegos4privacy) to discuss the whitepaper (https://github.com/stegos/stegos/wiki).

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