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Kaspa is the world’s first blockDAG- a ledger architecture enabling parallel blocks & instant transaction finality. Propagated by a robust proof-of-work engine with rapid single-second block intervals, Kaspa is an open-source, decentralized, & fully scalable Layer-1.

Built by industry pioneers, led by the people.

Fastest Transactions

The ability for cryptocurrency to be utilized for everyday transactions has been limited by a lack of speed in the most popular networks, such as Bitcoin and Ethereum. This has prevented their mass adoption.  Limitations in speed are due to an inherently poor design of linear blockchains which do not have the capability to process transactions quickly enough. Kaspa solves this problem through a novel approach “blockDAG” which creates multiple blocks every single second.  This approach means transactions get entered into the network and ready for confirmation almost instantly.

Instant Confirmation

After transactions have been entered into a specific block on a blockchain, these transactions must be fully validated and confirmed by a network of nodes.  Confirmation is required  to ensure that each spender and receiver’s ledger has been correctly calculated, that funds are available, and that each transaction is in fact a true one, and not an attack from a possible hacker.  Slow confirmation times have plagued cryptocurrencies for years.  Kaspa solves this confirmation bottleneck by publishing each transaction on the blockDAG in one second, and getting full validator confirmation in 10 seconds on average. After the rust upgrade, we expect these times to decrease even further. 

Scalable

Having a fast block ledger with instant confirmations is very important for users, but how many people and transactions can the ledger handle at a single time?  Could thousands of people transact at the same time with no impact on  speed or  confirmation? What about hundreds-of-thousands of people? How about millions to billions of people?  These questions highlight the scalability problems inherent with  most blockchains, meaning that they get clogged or don’t function as designed when a large number of users and transactions occur within a short period of time.  Thanks to the blockDAG design of Kaspa, we are better able to handle large amounts of transactions within very short periods of  time, with multiple numbers of  blocks being  created simultaneously and at an average rate of one block every second (wow that’s a lot of blocks!).  This allows us to pack in a large number of transactions in very short durations of time.  This is singularly unique for a true and purely decentralized proof-of-work network.

Efficient Proof-of-Work

Kaspa is a “pure” proof-of-work, and decentralized digital asset. While many projects are moving away from decentralization in order to scale and operate faster, Kaspa has persevered to solve these scalability and speed issues within a truly decentralized system.  Decentralization is the heart of all cryptocurrencies, free from the manipulation of central entities and large stake holders.  In order to keep decentralization intact while addressing any possible environmental negatives associated with mining, Kaspa has strategically chosen kHeavyHash.  This algorithm is a very efficient ‘core heavy’ algorithm that allows very high hashing power per watt (as compared to most PoW algorithms such as ETHash, SHA-256, KawPow). kHeavyHash is also amenable to future optical mining systems which have the potential to utilize even less energy. In addition to utilizing an efficient algorithm, Kaspa’s BlockDAG does not waste any blocks (thus conserving energy).  Each Kaspa block and chain contributes to the network security and none are discarded as opposed to Bitcoin and many other POW blockchains that regularly dispose of significant amounts of computational power when duplicate blocks are encountered.

Security

Kaspa employs the same security principles and methodology as bitcoin besides replacing SHA-256 PoW encryption with kHeavyHash.  kHeavyHash, which inherits all the security properties of SHA-256, is a modification of the SHA-256 hashing algorithm which also includes a weighting function. Thus, the blockDAG is secured by a robust network of decentralized volunteers (miners) who validate and sign transactions. Like Bitcoin, Kaspa is also fully decentralized and permissionless.  Anyone can participate and anyone can help secure the network.

BlockDAG

Kaspa is the first blockDAG cryptocurrency (no blockchain). A blockchain is a linear system, where transactions are recorded in blocks, which are ordered by time and sealed. A blockDAG is a directed acyclic graph- a mathematical structure where the vertices represent blocks & edges reference child/parent blocks. This novel implementation of distributed ledgers is the first of its kind – permitting next-generation scalability, high throughput transactional bandwidth, instantaneous confirmations, while remaining decentralized. Please read below for more detailed technical information on blockDAGs.

Core Technology

Kaspa is a revolutionary advancement in technology based on years of academic and theoretical research.

Nakamoto Consensus Engine

Nakamoto consensus, named aptly after Satoshi Nakamoto, is the very first consensus engine based upon a proof-of-work mechanism and is to this day still securing the bitcoin network, as well as many other Proof-of-work cryptos, including but not limited to, well known cryptocurrencies such as Litecoin, Bitcoin Cash, and ZCash. 

The security properties of the Nakamoto consensus have been proven mathematically, are considered theoretically sound, and have been tried and tested practically in Bitcoin and its variants, over the last 14 years, without any major incidents. The bounds for manipulating the blockchain are both simple and verifiable; Any actor who wishes to exploit the blockchain must control over 50% of the hashrate (i.e. computing power) on the network. This, as the network grows, is considered to become evermore infeasible.

 This simple concept is one of the main factors why trust in Bitcoin remains high, and a catalyst behind it being adopted, as both a store of value, and a payment system, by many mainstream institutions worldwide.

In contrast, many new forms of consensus, that have moved away from the original Nakamoto consensus vision have adopted a proof-of-stake approach which seeks to scale and add speed at the expense of decentralization. 

BlockDAG

The term “DAG” stands for Directed Acyclic Graph, a mathematical concept for a directed graph with no directed cycles. It consists of vertices and edges, with each edge directed from one vertex to another.  In the context of distributed ledgers, BlockDag is a DAG whose vertices are blocks, and edges are references from blocks to their predecessors.  The blockDAG seeks to solve the problems with linear blockchains and Nakamoto consensus. These problems include lack of scalability, selfish mining, and orphan blocks. Unlike a traditional blockchain, blockDAGs may reference multiple predecessors instead of a single predecessor and blocks reference all tips of the graph instead of just referencing the tips of the longest chain.  By referencing all tips of the graph, a blockDAG incorporates blocks from different branches instead of just referencing the longest chain.

Thus, in a BlockDAG, no blocks are wasted or orphaned, all blocks are published to the ledger, and no mining power is wasted.  Due to this structure, blocks are allowed to be generated more frequently, facilitating more transactions, and resulting in almost instant confirmations. How is this all possible?  By deviating from the longest chain consensus method, and leveraging Kaspa’s novel GhostDAG (Phantom 2.0) consensus mechanism.

BlockDAGs are superior to singular or parallel block chains due to the maximal revelation principle. When you mine a block, and share all the tips of the blocks you are aware of, you maximize the information you send.

GhostDAG

GhostDAG is the consensus mechanism which Kaspa currently utilizes and improves upon the PHANTOM consensus. PHANTOM requires solving an NP-hard problem, and is not suitable for practical applications on its own. Instead, we use the intuition behind PHANTOM to devise a greedy algorithm, GHOSTDAG, which can be implemented more efficiently. We prove formally that GHOSTDAG is secure, in the sense that its ordering of blocks becomes exponentially difficult to reverse as time develops. The main achievement of GHOSTDAG can be summarized as follows: Given two transactions tx1, tx2 that were published and embedded in the blockDAG at some point in time, the probability that GHOSTDAG’s order between tx1 and tx2 changes over time decreases exponentially as time grows, even under a high block creation rate that is non-negligible relative to the network’s propagation delay, assuming that a majority of the computational power is held by honest nodes.

Similar to PHANTOM, the GHOSTDAG protocol selects a k-cluster, which induces a coloring of the blocks as Blues (blocks in the selected cluster) and Reds (blocks outside the cluster). However, instead of searching for the largest k-cluster, GHOSTDAG finds a k-cluster using a greedy algorithm. The algorithm constructs the Blue set of the DAG by first inheriting the Blue set of the best tip Bmax i.e., the tip with the largest Blue set in its past, and then adds to the Blue set blocks outside Bmax’s past in a way that preserves the k-cluster property.

Observe that this greedy inheritance rule induces a chain: The last block of the chain is the selected tip of G, Bmax; the next block in the chain is the selected tip of the DAG past (Bmax); and so on down to the genesis. We denote this chain by Chn(G) = (genesis =Chn0(G), Chn1(G), . . . , Chnh(G)). The final order over all blocks, in GHOSTDAG, follows a similar path as the colouring procedure: We order the blockDAG by first inheriting the order of Bmax on blocks in past (Bmax ), then adding Bmax itself to the order, and finally adding blocks outside past (Bmax ) according to some topological ordering. Thus, essentially, the order over blocks becomes robust as the coloring procedure.

Pruning

Pruning is a method employed in Kaspa to reduce the size of the blockDAG.  This prevents nodes from having to keep registry of very large amounts of blockDAG data.  Due to the pruning mechanism, Kaspa nodes only needs ~3 days of prior history to be stored by each decentralized machine. This allows for many nodes to be created for our network with no large storage requirements.

The pruning mechanism that Kaspa employs is unique to our blockDAG and GhostDAG consensus method. The goal was to design a pruning algorithm that is resistant to pruning attacks by a 49% attacker. Our design approach employs the apparatus of finality and invalidation rules.

1.) Finality is the practice of not allowing reorgs below some fixed depth, blocks which weren’t finalized may not be pruned. On the other hand, it is not generally true that finalized blocks may be pruned, as the data they contain might be needed to compute the UTXO set of incoming blocks.

2.) Invalidation Rules:  The first rule: If a block is invalid then so is any block pointing to it. Since we discard such blocks, we can’t trust blocks which point at them as the data is unavailable. The second rule: a block B is invalid if there is a block D in B.Past which is in B.P.Anticone, for which there is no kosherizing block. The third rule: Bounded Merge, or limiting the size of the merged sets of blocks, such that a merged set of block B defined to be the set of blocks in B.Past which are neither B.SelectedParent nor in B.SelectedParent.Past get constrained by a fixed parameter: L.