Simplified Payment Verification

What Is the Simplified Payment Verification (SPV)?

SPV stands for Simplified Payment Verification, a lightweight solution for verifying blockchain transactions. It works by downloading the block headers and asking for proof of inclusion to the blockchain through the Merkle Tree. It is particularly beneficial for what are known as “light clients.” Light clients are wallets that are operating on low-end systems. 

A Merkle Tree is a tree-like arrangement in cryptography through which every leaf node is marked with the hash of a data block. Likewise, all non-leaf nodes are marked with the cryptographic hash of the labels of their leaf nodes. 

The Simplified Payment Verification (SPV) lets its clients assess if a transaction is included in the bitcoin network or not. SPVs also allow light clients to determine whether a transaction has been included in BTC. This makes SPVs useful for transaction verification and conformation of their execution.

Using SPVs can be very useful as they help simplify the process. For example, running a full node and a Merkle Tree requires that the user download the entire blockchain, which requires a lot of processing capacity. When users use the SPV process, they only need the root of the Merkle Tree compared to the entire tree. 

Using the SPV means that just 80 bytes per block need to be stored compared to the significantly larger block sizes needed per block when SPV is not utilized for transaction processing.

Issues with using the Simplified Payment Verification (SPV)

Using the SPV system has some problems, like the comparatively weak security of the process. 

Moreover, in case of an attack on a cryptocurrency, hackers can successfully issue SPV verification prompts and validate illegal transactions. 

There is research to find mitigants for such threats as the SPV is a handy tool. A whitepaper by Nakamoto stated that transactions using Bitcoin could be verified without using the entire node network.