February 23, 2017

FAQ

Fundamentals

What is RSK?

RSK is the first general purpose smart contract platform secured by the Bitcoin Network.

What is a smart contract?

Smart contracts are contracts whose terms are encoded in  computer language instead of legal language. Smart contracts can be executed by a computing network such as RSK, so that the terms of the contracts are automatically enforced by a protocol that all nodes in the network follow.

A smart contract can be fully autonomous if all the objects referred (such as currency, payments, obligations, property titles, assets, licenses) have a digital representation in the platform. When there is no such digital representation for an object, a smart contract can also refer to itself and react to changes in its state though special gateway nodes called oracles -that provide external information to the blockchain. A smart contract also has access to time with minute precision, so time-restricted conditions can be represented.

 

A few examples of smart contracts are:

Micro-lending

Distributed voting systems

Machine to machine payments

Decentralized exchanges

Asset tokenization

Supply chain tracking

Loyalty and rewards

Micro-insurance

Crowdfunding

Property registry

Escrow services

Transparent public tenders

Remittances

What is RSK’s mission?

To optimize cross-industry processes focusing on financial inclusion, public administration transparency and IOT.

Will RSK mint a new coin?

No. The RSK platform uses Bitcoin as its native currency. A 2-Way Peg between Bitcoin blockchain and RSK blockchain ensures a fixed conversion between BTC and SBTC. (1 SBTC = 1 BTC).

How many transactions per second will RSK Network withstand?

Considering current technology trends regarding SSD storage in network nodes, RSK network can withstand 400 tx/sec (simple payment transactions).However, RSK goal is to reach 2K transactions per second using its Lumino technology, which is a 2nd layer network that will be embedded on RSK’s following release.

How does the Ethereum compatibility works?

RSK smart contracts are programmed on Solidity and RSK VM is fully compatible with Ethereum VM. Future versions of the RSK Platform will include improvements to Ethereum VM which might require minor changes to the smart contracts in order to use this new functionalities.

What mining algorithm does RSK use?

The RSK blockchain is secured by proof-of-work based on SHA256D algorithm (same algorithm that Bitcoin uses). This enables Bitcoin miners to mine on both chains at the same time with exactly the same resources and with no performance harm on Bitcoin mining.

Why would Bitcoin miners mine in RSK chain?

The merge-mining functionality allows Bitcoin miners to mine in both chains with almost no extra cost. This will provide them extra revenues based on fees and allow them to participate in the smart contracts business.

What is the current state of the project?

We are currently working on our Production-ready network, codenamed Ginger. Our fully-featured private testnet, codenamed Turmeric B, is active.

 

Security

How is the RSK blockchain secured?

RSK blockchain is secured by a unique combination of security measures. On one hand, RSK blockchain is mined by the Bitcoin network miners, which is the largest and most reliable blockchain network in the world. On top of this, a group of the 25 most renowned and trusted Bitcoin companies distributed in more than 20 countries provide an extra layer of security issuing security checkpoints on the blockchain.

The RSK 2-Way Peg is designed as a hybrid security model where the multi signatures are held by a combination of the POW of the miners and the Federation.

What is the 2-Way Peg?

The 2-Way peg is often said to be a method to transfer BTC into SBTC and vice-versa. In practice, when BTC are exchanged for SBTC, no currency is “transferred” between blockchains. There is no single transaction that does the job. This is because Bitcoin cannot verify the authenticity of balances on another blockchain. When a user intends to convert BTC to SBTC, some BTC are locked in Bitcoin and the same amount of SBTC is unlocked in RSK. When SBTC needs to be converted back into BTC, the SBTC get locked again in RSK and the same amount of BTC are unlocked in the Bitcoin blockchain. A security protocol ensures that the same Bitcoins cannot be unlocked on both blockchains at the same time.

How does the peg work?

When a Bitcoin user wants to use the 2-Way Peg, he sends a transaction to a multisig wallet whose funds are secured by the Federation. The same public key associated with the source bitcoins in this transaction is used on the RSK chain to store the Smart Bitcoins. This means that the private key that controlled the Bitcoins in the Bitcoin blockchain can be used to control an account on the RSK chain. Although both public and private keys are similar, each blockchain encodes the address in a different format. This means that the addresses on both blockchains are different.

What are the differences between a Bitcoin address and an RSK address?

An RSK address is an identifier of 40 hexadecimal characters while the Bitcoin address is an identifier of 26-35 alphanumeric characters.

How does RSK secure the funds locked in the peg?

The funds in the peg are initially secured by a threshold signature managed by the Federation. At least 51% percent of the Federation members signatures are required to transfer bitcoins out of the peg wallet. However, once Bitcoin soft-forks to support the drivechain BIP RSK proposed, unlocking funds from the peg will require 51% percent acknowledgement by the merge-mining hashing power as well. With the drivechain BIP, the merge-miners obtain veto power, and can prevent a transaction created by the Federation from spending collateral without the automatic authorization provided by the RSK blockchain.

How is the RSK blockchain secured from double-spend attacks?

The RSK blockchain is secured by proof-of-work based on SHA256D algorithm like Bitcoin. If all the RSK miners collude, they can censor one or all of RSK transactions but they cannot steal Smart Bitcoins or Bitcoins. Also, RSK miners cannot double-spend, as the Federation provides the checkpointing service, and every Federation member node is highly connected to the RSK network to prevent Sybil attacks. The Federation will use the checkpointing power to prevent reorganizations of high depth which are not related to a protocol fault.  The Federation cannot double-spend, as a Federation member is not allowed to checkpoint two blocks having conflicting transactions.

Will RSK platform be more secure than Bitcoin?

The security of the RSK platform will depend on the amount of merge-mining engagement and the number and quality (security compliance) of the Federation members. More than 30% of the Bitcoin miners are already working with RSK and a 50% remaining is planning join RSK mining, so we expect to reach more than 51% of Bitcoin miners to be securing the RSK network. As the Federation adds a second layer of defense, we can expect the RSK platform to be, from the consensus point of view, more secure than Bitcoin.

How does N confirmations in Bitcoin compare to N confirmations in RSK? Is 6 confirmations enough in RSK as it is in Bitcoin?

A recent paper established that in terms of the transaction reversal probability due to normal statistical variance, 6 Bitcoin confirmations (average 1 hour) would be equivalent to approximately 12 RSK confirmations (average 2 minutes). While Bitcoin has the concept of 0-confirmations (the transaction has been broadcast without Replace-by-fee), there is no similar concept in RSK. The fastest real confirmation in RSK is “1.5” confirmations, or 1 confirmation plus 5 seconds without a block reversal, or an average of 15 seconds.

Is RSK secure from users using blockchain resources (CPU, bandwidth, storage) for free?

The RSK “gas system” prevents an attacker from creating, spreading and including resource-intensive transactions in blocks without paying the associated fees. Every resource, including CPU, bandwidth and storage is accounted by consumption of an amount of gas. Every block has a gas limit, so the resources a block can consume are limited, making a resource exhaustion attack ineffective.  

Is RSK secure from miners abusing the gas system to cheaply acquire resources as in Ethereum?

In Ethereum a miner can include transactions specifying zero gas price, thus acquiring persistent contract state memory almost for free. However, as most Ethereum blocks are empty, and there is no backlog of fee-paying transactions, the cost is currently zero. In RSK a high percentage of the transaction fees go into a reward pool for future miners, a small fraction of the transaction fees are burned and there is a minimum gas price negotiated by the miners. Therefore, rogue miners cannot get platform resources at no cost.

Is RSK planning to do hard forks?

First, RSK has no right to enforce a hard-fork once the platform is launched. Changes that aim to improve the network in terms of privacy, scalability, security or ease of use will be proposed by RSK team. The participants of the RSK network must decide by themselves to accept or reject any change proposed by RSK or by any other member of the community.

Note: RSK WILL NEVER PROPOSE A FORK TO INTERVENE IN A SITUATION BETWEEN PARTIES OR USERS SUCH AS THE DAO SITUATION. THE ONLY HARD FORKS THAT RSK WILL EVER PROPOSE ARE THOSE TO IMPROVE THE SECURITY AND/OR FUNCTIONALITY OF THE PLATFORM.

How is RSK going to deal with privacy?

RSK is working in parallel in a “private RSK” network with PBFT consensus. However, our aim is to help companies to easily integrate with the public RSK platform. The private RSK network will be available at sometime in mid 2017. In our Bamboo release (Q4 2017) we’ll be adding a technology for confidential transactions.

How will RSK deal with scalability?

RSK is addressing scalability through different fronts, the base layer (RSK) and a second layer (Lumino). Our main contribution to the base layer scalability is using multi-threading based block verification, which reduces the cost of verification with a factor close to the number of processor cores. Miners use a dependency detection algorithm to setup execution threads. We have many more improvements planned for the 2.0 release regarding base layer scalability.

To reach 200M users, a new, second layer network will be deployed. The Lumino network is a payment network which can scale up to 2K payments/second in a decentralized setting, and in most properties outcompetes the Lighting Network. It does not require complex routing algorithms nor it requires pre-locking of the funds.

Is RSK planning to upgrade from ECDSA to any other signature scheme ?

RSK plans to allow user-defined signature schemes. This means that RSK users will be able to choose other signature schemes for their accounts (for example, a quantum-cryptography-proof schemes). This can be done by adding to accounts a state-less script that verifies free-transaction signatures. This will allow the use of Merkle-Winternitz, RSA, edDSA and other signature schemes.

 

Miners & Pools

What is merge-mining in RSK and how secure it is?

Merge-mining is a process in which Bitcoin miners can mine both Bitcoin and RSK at the same time, with the same hardware and consuming the same electricity. RSK merge-mining uses the same cryptographic hash function as Bitcoin (SHA256). However there is an important difference: Bitcoin always uses double SHA256, while RSK merge-mining security is of single SHA256. Also, RSK merge-mining assumes a stronger property from SHA256, freestart collision security of at least 100 bits. This is because RSK uses a property of the Merkle–Damgård construction to compress the size of the SPV proof.

What is the DECOR+ protocol?

In the Bitcoin network, when two or more miners have solved blocks at equal height, there is a conflict of interests. Each competing miner wants his block to be selected by the remaining miners as the best-chain tip. All the remaining honest miners and users would prefer that everyone chooses the same block tip, because this reduces the block reversal probability. DECOR+ sets the right economic incentives for a convergent choice, without requiring further interaction between miners. The conflict is resolved so that:

  1. The resolution is agreed when all parties have access to the same block-chain state information.
  2. The resolution maximizes all miners revenue when the conflicting block revenue (fees) is much higher than the average.
  3. The resolution reduces the power of the miners to censor other blocks or transactions when the conflicting block has a reward close to the average.
  4. Resolving the conflict takes negligible time.

Is RSK secure from selfish mining?

DECOR+ is incentive-compatible as long as the transaction fees are close to the average. Which means that miners gain nothing from withholding blocks.

Given certain conditions (such as low revenue and the large transaction throughput), the miners would not verify the block contents, which could be a major vulnerability. Do you address this problem in the RSK design?

The RSK miners do not verify block content for a few seconds, and that’s part of the DECOR+ protocol. Miners can create child blocks even when they have not finished verifying the parent block. Blocks created without parent verification are marked for the network to act accordingly. However, there can’t be two empty blocks in a row. Miners mining empty blocks are also rewarded, by sharing a part of past block fees.

 

Federation

What is the Federation?

The RSK platform will be launched with a Federation of well-known and respected community members (blockchain companies with high security standards). Each member is identified by a public key for the block checkpoint signature scheme. The Federation is able to add or remove members using an on-chain voting system. The conditions to become a Federation member (known as Federation Member Requirements or FMR) establish basic security policies and legal requirements that all members must meet.

What services does the Federation provide?

The Federation will provide several services to the network. Some of them will be available at launch and other will be added later. Each member can choose to provide any of the following services:

  • Two-way peg with Bitcoin
  • Two-way pegs with other cryptocurrencies
  • Oracling services
  • Checkpointing services

What is the 2-Way peg service that the Federation provides?

Bitcoin does not support smart contracts nor native opcodes to validate external SPV proofs. Part of the 2-Way Peg system in RSK requires trust on a set of a semi-trusted third-parties (STTP). In RSK, the STTPs that protect the locked funds are a subset of the the members of the Federation. The Federation members are respected community actors, such as important blockchain companies, and they also have the technical ability to maintain a secure network node.  A requirement for being part of the Federation is the ability to audit the proper behaviour of the software that powers the node, specially regarding the correctness of the component that decides on releasing BTC funds.

What are the Federation checkpoints?

In order to add an extra layer of security, the RSK protocol accepts federated checkpoints on the blockchain. Federated checkpoints are signed by the Federation members and clients can use the majority of the signatures to better decide which is the best chain.

Will the Federation cease to help securing the 2-Way peg?

Once Bitcoin adds special opcodes or extensibility to validate SPV proofs as a hard-fork, or to manage a drivechain, the Federation role as STTPs in the 2-Way peg will no longer be necessary. Until that happens, we expect the Federation and the sidechain validation to coexist.

When will the Federation stop making checkpoints?

By default, clients stop using federated checkpoints when if RSK hashing power is over 66% of the maximum BTC hashing difficulty observed in the best chain and the fees paid in a block are higher or equal to the average reward of a Bitcoin block. However, any user can re-configure this local policy.

 

RSK’s FAQ is constantly updated.

For feedback or further questions, please contact us at info@rsk.co

Thank you!

RSK Team