What is an Orphan Block?

In a cryptocurrency network, one of the most important components is blockchain technology. Cryptocurrency builds its foundation on a public ledger that is distributed and transparent. On this ledger, all transactions made with a cryptocurrency are put into the “blocks” before going onto the “chain.” For all of the blocks on the chain, there are some that fail to gain acceptance. These are the ‘orphan blocks’.

An overview of mining

A blockchain contains a series of blocks acting as data storage units. Within them are various details of the transactions taking place on the blockchain network. Amid the mining procedure, miners actively try to generate new blocks for the chain. The process behind this is solving complex mathematical equations that are necessary for the blockchain network operation.

The first miner who can successfully generate a new block can obtain the block reward. Moreover, they are able to write the first transaction on the new block they found. If the blockchain network wants to function properly, then the new block will be added as the new ‘unit’ on the chain.

As one can probably tell, crypto mining produces a win-win outcome. For computers, when they solve these complex problems on the network, they produce new crypto. In a way, it is not all that different from a traditional mining operation extracting gold. For miners, they will make the crypto payment network reliable and secure through transaction information verification. The network acquires more blocks and the miners will be rewarded for their efforts.

What are they?

An ‘orphan block’ is a block whose parent block is either unknown or does not exist. The formation of these particular blocks mainly stems from older versions of the Bitcoin Core software. Here, network nodes could receive blocks regardless of the lack of data concerning their origins.

Nowadays, the term is still quite common in the crypto space when referring to discarded mined blocks. These blocks should technically be ‘stale blocks’ or ‘extinct blocks’. However, because the client designates their block rewards as “orphaned,” a lot of people refer to them as orphan blocks. Therefore, even if the parent block is known, many still call those blocks ‘orphan blocks’ instead of ‘stale blocks’.

Generating stale blocks occurs when two different miners relay their credible blocks at approximately the same time. This results in the network splitting into two clashing versions of the blockchain until one of the blocks is scrapped. The longest chain will prevail while the other will be abandoned. Both blocks undergo verification and prove to be valid, but only one will attach to the primary chain.

How blocks are orphaned

The odds of two miners producing a block at almost the same time are actually pretty good. This situation happens due to block acceptance by the nodes of the blockchain network is not instantaneous. This noticeable delay in accepting a block could lead to another miner trying to solve for the same block. It leads to temporary disorder on the blockchain network while the nodes try to decide which of the two new blocks it will accept.

In these situations, the block that has the larger share of proof-of-work will go onto the blockchain. The other block – the one with a smaller proof-of-work – will be discarded and will be known as an orphan block. Blocks of this kind are essentially valid blocks with proper verification, but that does not matter. Because of the network’s working mechanism and the time lag in gaining acceptance, one of the blocks will be rejected. In other words, orphaned.

This is not the only process of orphan block creation. Another way is when a hacker possessing adequate hashing power tries to reverse some transactions. Specifically, ones that had previously occurred in the blockchain network. From here, let’s get into a particular brand of attacks that connect to orphan blocks.

51% attacks

It is not just situations where several miners find a block at about the same time that orphan blocks appear. They can also pop up in attack situations. Case in point, 51% attacks.

A 51% attack is an attack on a blockchain by a group of miners. These miners are typically those in control of over 50% of the network’s mining hash rate or computing power. The attackers could prevent new transactions from acquiring confirmations, allowing them to cease payments between users. Additionally, they could reverse completed transactions all the while they take control of the network. This means that they are able to double-spend coins.

This infamous type of attack is one of the few weaknesses of the Bitcoin blockchain. An attacker can utilize their majority portion of the network hash rate to conjure up their own version of the blockchain. When it comes to which block the network will view as valid, the longest chain is the most important component. However, a miner owning 51% of the network can develop their own blockchain at a comparatively faster rate than everyone else.

Put simply, an attacker can assemble their chain consisting of orphan blocks to take control of the Bitcoin ledger. Suppose that someone can centralize power over Bitcoin’s history of events. If this happens, then they have the ability to double-spend their bitcoins. What’s more, they can also hinder other people from using the network.

A common misconception

Orphan blocks are typically a confusing topic of discussion in the crypto space. Even miners with the most experience usually find the terminology to be slightly off. Generally speaking, these types of blocks are not technically orphans. At least, not in the traditional context that we normally associate “orphan” with. They do in fact have parents in the form of the previous blocks residing in the chain.

In actuality, the part of the blocks that are orphaned are the payouts. It is conceivable that this commonly incorrect phrasing derives from these ‘stale blocks’. More often than not, people refer to these as orphan blocks. Believe it or not, it is possible for orphan blocks to also have ‘children’.