Shabal / Sha256 / Curve25519

Shabal, Sha256 and Curve25519 are cryptographic hash functions used in this text. Shabal is the main one used by Burstcoin. Shabal is a rather heavy and slow cryptographic hash function in relation to many others like SHA256. Because of this, it makes it a good crypto for Proof-of-Capacity coins like Burstcoin. This is because we store the precomputed hashes, and it is still fast enough to do smaller live verifications. Burst uses the 256bit version of Shabal also known as Shabal256.

Hash / Digest

A hash, or digest in this context, is a result when computing data through a cryptographic hash function. If not said otherwise, the length of a hash is 32Bytes (256bit).

Plot files

When mining, you read precomputed hashes from files stored on a storage device. These files are called plot files.


Within a plot file, there are one or more groups of data called nonces. One nonce contains 8192 hashes, and because of that, the nonces are 256KiB large. Each nonce has its own individual number. This 64bit number can range between 0-18446744073709551615 (264).


Each nonce is sorted into 4096 different places of data. These places are called scoop numbers. Each scoop contains 2 hashes. Each of these hashes are xored with a final hash.

Account ID

When you create your plot file it will be bound to a specific Burst account. Because of this, all miners have different plot files.


When you mine and process your plot files, you will end up with resulting values called deadlines. The values represent the number of seconds that must elapse since last block was forged before you are allowed to forge a block. If no one else has forged a block within this time, you can forge a block and claim a block reward.

Block reward

If you are lucky enough to forge a block, you will get Burstcoin as a reward. This is called a block reward. The block reward decreases 5% every 10800 blocks. This is roughly every 30 days since each block is supposed to be forged every 4 minutes (360 blocks a day).

Base target

Base target is calculated from the last 24 blocks. This value adjusts the difficulty for the miners. The lower the base target, the harder it is for a miner to find a low deadline. It gets adjusted in a way that Burstcoin can have an average of 4 minutes for each block.

Network Difficulty

Network Difficulty, or NetDiff in short, is a value that can be read as an estimate on the total amount of space in terabytes dedicated to mine Burstcoin. Since this is a value that changes with every block in relation to base target, it should be taken into an average of at least 360 values before considered to be somewhat accurate.

Block Height

Every block forged gets an individual number. Every new block forged gets the previous block’s number + 1. This number is called block height, and can be used to identify a specific block.

Block Generator

When a block is forged, an account has found a nonce and a deadline. Block generator is the account used when forging a block. This is the account from which a deadline has been found when forging a block. This is always the real account even if a reward assignment has been set.

Generation Signature

Generation signature is a based from the previous block generation signature and block generator. This value is then used by miners to forge a new block. Generation signature is 32bytes long.

Block signature

Every block is signed by the generator who forges a block. This is done by taking most parts of the block and signing it with the block generator’s private key using both Sha256 and Curve25519. The result is a 64byte long hash.

Reward Assignment

Reward assignment is frequently used when pool mining.  When changing your reward assignment, you tell the network that another account (the pool account) is acting in your place for 2 specific features. The first feature is that all block rewards that should be given to your account will now be given to the pool account instead. Secondly, for the pool to be able to utilize the deadlines found from your plot files, it is also granted the action to sign the newly forged blocks with the account belonging to the pool.