### Bitcoin Primitives: Hash Functions

I prefer to use the terms “data” and “hash”, but don’t be surprised if you run in to the other terms now and then.

## What Is a Hash? Hash Functions and Cryptocurrency Mining

This is just for my reference if nothing else, as I keep forgetting what each of these terms mean when reading about secure hash functions in textbooks. To obtain the new target, simply multiply the existing target by the ratio of the total actual block time over the last two weeks to get the expected block time. This will adjust the target proportionally to the amount of entering or exiting computing power on the network.

## Cryptographic Hash Functions: Definition and Examples

Hashes can ensure messages and files transmitted from sender to receiver are not tampered with during transit. The practice builds a “chain of trust.” For example, a user might publish a hashed version of their data and the key so that recipients can compare the hash value they compute to the published value to make sure they align. While they are considered cryptographically “weak” because they can be solved in polynomial time, they are not easily decipherable. Therefore, the more time a transaction has been part of the longest block chain, the more likely it is to remain part of the chain indefinitely. This is what makes transactions non-reversible and this is what prevents people from double-spending their coins. With this framework, we are able to achieve the essential functions of the Bitcoin system.

## What Is the Main Purpose of Hash?

A new merkle root and subsequently new block header are calculated, and the nonce is iterated over once again. Using Komodo’s multi-chain network, you can launch an independent Smart Chain and fully customize the network’s parameters. Choices for consensus mechanisms include Proof of Work, Proof of Stake, or a hybrid combination of the two. If you choose PoW, you can select one of five different variations of the Equihash algorithm or the VerusHash algorithm. The PoS implementation can be used in combination with PoW consensus rules.

## Bitcoin: Native SegWit Vs. Taproot

A hash is a mathematical function that converts a variable input to a deterministic hexadecimal number. Once the problem is solved, each node compares the block header by hashing it twice and comparing its result to the new block’s hash. For instance, miners solve Bitcoin’s hash problem by using the data in a block as input and generating a hash.

This fingerprint is called the merkle root, and it’s basically all of the TXIDs hashed together in a tree-like structure. Any change to a block lower down in the chain will change its hash, and therefore the Bitcoin Hash Functions blocks above it will no longer be connected to it and will no longer be part of the longest chain. Never enter your mnemonic sentence in to a website, or use a mnemonic sentence generated by a website.

- Every such algorithm has distinct features, including the important feature that each one produces unique hashes.
- If the hash does not meet the criteria of network difficulty, another nonce is selected and hashed.
- (Hashcash uses symmetric key cryptogaphy, namely a one-way hashcash function – typically either SHA1 or SHA-256).
- This hash function is an industry-standard function used widely in banking, information security, and communication networks.
- This is what makes transactions non-reversible and this is what prevents people from double-spending their coins.

## Basic Hash Function

The values returned by a hash function are called hash values, hash codes, hash sums, checksums or simply hashes. Recent development of internet payment networks and digital money, such as Bitcoin, also uses a form of ‘hashing’ for checksums, and has brought additional attention to the term. In particular, the creator of the Bitcoin protocol, Satoshi Nakomoto, chose to use the SHA-256 hash function as the basis for Bitcoin mining.

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