Introduction
The blockchain gets its name from its underlying structure. The blockchain is organized as a series of “blocks” that are “chained” together.
Understanding blockchain security requires understanding how the blockchain is put together. This requires knowing what the blocks and chains of blockchain are and why they are designed the way that they are.
Inside the blockchain block
The blockchain block is the data storage component of the blockchain’s distributed ledger. Each block in the blockchain contains a number of different transactions that it adds to the shared state of the blockchain network.
The image above shows a simple representation of several different blocks within a blockchain. The blocks are divided into two parts: the header (across the top of the image) and the body (represented by the tree dangling from block 11 in the image).
Inside the blockchain header
When discussing the structure of the blockchain, it is often described as a series of blocks that are linked together in a way that protects them against modification. However, it is only the headers of the blocks that are actually linked together in this way.
The header of a block in a blockchain can have a number of different fields, depending on the details of the particular blockchain implementation. However, the four fields shown in the image above are fairly common and each is significant to the operation of the blockchain:
- Previous block hash: This value implements the “chains” in blockchain. More on it in a later section
- Timestamp: This indicates roughly when a block was created. It is used by smart contracts that depend on timestamps and to determine how well the current average rate of block creation matches the target value
- Transaction root: This value summarizes the contents of the block’s body. It helps to ensure that (Read more…)