Understanding Bitcoin Block Header Versions
For a beginner in cryptocurrency, it is important to understand the inner workings of Bitcoin and its blockchain architecture. In this article, we will delve into the concept of block header versions and find out what miners can correct when hashing them.
What is a block header?
A block header is the first 4–6 bytes of data that precede each block in the Bitcoin blockchain. It contains information about the contents of the block, such as the previous hash (ie the « parent » block), the block number, and the unique block identifier.
Bit String Version
Version numbers are usually represented by 8-bit binary strings that can take values from 0 to 255. However, when miners update the block header, they often change the version number to a random bit string (in this case, one byte). . At first glance, it may seem unusual, but in fact it is a smart mechanism used for optimization and scalability.
The underlying reason for the version bit strings
In Bitcoin, every 4-byte block must have a valid hash. When a miner updates a block header, it creates a new block by hashing its current block. The resulting hash value must match the expected hash of the previous block in the blockchain. However, if the version number changes, it can lead to conflicts and inconsistent hashes.
Miner’s Challenge
By changing the version number, miners try to avoid these conflicts and ensure that each block is hashed correctly. They do this by adjusting the string of bits at the end of the 4-byte header (the last byte). This modification has a significant impact on the overall value of the hash function of the block, which, in turn, affects the validity of the block.
Usage Example
Let’s look at an example that illustrates how miners can adjust the block header. Suppose we have a miner with the following block header:
Original main caption:
Version: 0x12345678
Previous hash: 0x90123456
New main caption (with corrected version):
Version: 0x87654321
In this case, the miner successfully updated the block header by changing the last byte from « 1234 » to « 7654 ». This change affects the overall hash value of the block and guarantees its validity.
Conclusion
Understanding how miners correct block headers is essential to understanding the architecture of the Bitcoin blockchain. Version bit strings are a smart mechanism used to optimize and scale the network, ensuring that each block is hashed correctly. By correcting these versions, miners can avoid conflicts and maintain the integrity of the blockchain.