Blockchain 101

How are Blockchains Secure?

Records on a blockchain are secured through cryptography and network architecture.

Public and private key cryptography:

What are public and private keys? Read about them here.

Network participants have their own private keys that are used to sign transactions. A transaction is signed with a personal private key creating a digital signature. If a record is altered, the signature will become invalid, and the peer network will be alerted of this invalid transaction.

A digital signature created by signing a message with the sender’s private key can be verified by anyone who has access to the sender’s public key. As public keys are derived from private keys, this verifies that the message was sent from the holder of the private key. This ensures that the message is unchanged between the sender and the receiver.

Decentralized network architecture:

Blockchains are decentralized and distributed across peer-to-peer networks that are continually updated to reflect every transaction. Because they are not contained in a central location, blockchains do not have a single point of failure and cannot be changed by hacking a single computer. It would require massive amounts of computing power to access the necessary majority of a blockchain and alter each node at the same time. See the lesson on 51% attacks.

We have much more information accessible in our Blockchain Security course!

Decentralized networks open up an avenue to internet users regaining their digital identities, along with several other benefits. In order for decentralized networks to get to this point of viability, they had to address the security concerns presented by these networks. There are several technical components of a blockchain that is crucial to its functionality, which we’ll explore in our next module.