E018 – Tech Spec – Sia, ultimate blockchain file storage

What if you could store your data in the cloud, encrypted, for a fraction of the cost of Amazon S3, Google, or Azure? With Sia, a decentralized file storage solution that leverages blockchain, you can. Learn more about how it works in this episode.

Blockchain Overview

A blockchain is a permissionless distributed database that maintains a continuously growing list of transactional data records. The system’s design means it is hardened against tampering and revision, even by operators of the nodes that store data. The initial and most widely known application of the block chain technology is the public ledger of transactions for bitcoin, but its structure has been found to be highly effective for other financial vehicles.

[Illustration by Matthäus Wander (Wikimedia)]

Timestamp: The time when the block was found.
Reference to Parent (Prev_Hash): This is a hash of the previous block header which ties each block to its parent, and therefore by induction to all previous blocks. This chain of references is the eponymic concept for the blockchain.
Merkle Root (Tx_Root): The Merkle Root is a reduced representation of the set of transactions that is confirmed with this block. The transactions themselves are provided independently forming the body of the block. There must be at least one transaction: The Coinbase. The Coinbase is a special transaction that may create new bitcoins and collects the transactions fees. Other transactions are optional.
Target: The target corresponds to the difficulty of finding a new block. It is updated every 2016 blocks when the difficulty reset occurs.
The block’s own hash: All of the above header items (i.e. all except the transaction data) get hashed into the block hash, which for one is proof that the other parts of the header have not been changed, and then is used as a reference by the succeeding block.

Sia Overview

Decentralized network that places encrypted pieces of your data on dozens of notes
Aims to be fastest, cheapest, most secure storage solution and compete with AWS, GCP, Azure
Users pay in Siacoins, a cryptocurrency like Bitcoin
- Must go USD -> Bitcoin -> Siacoin -> Wallet -> File Upload
Open source
Started by David Vorick and Luke Champine through a VC backed Boston-based company called Nebulous Inc
Origins in the HackMIT 2013 conference
Uses ASICs (application specific integrated circuits) for mining
- These are purpose built integrated circuits, not general multi-use devices
- Evolution from CPU -> GPU – ASIC
- Faster and less vulnerable to attacks than GPUs
- Why? See here.
- Created a company to make ASICs called obelisk.
- ~$2,500 per machine
Current price is about 124 Siacoin to $1USD

Pros

Decentralized, peer-to-peer
Encrypted and immutable
Hosts can earn money by renting free disk space to renters
- Must maintain 95% uptime to preserve collateral

Possible Issues

Renters uploading illegal content to hosts
- However, renters would have to pay for the bandwidth leechers use to download files
Slow at this point
Low number of users