Thread by @immunefi

This is part 1 out of a 2 part thread series dedicated to Signatures in Ethereum.

It was inevitable that sooner or later, we would need to talk about this.

But bear with us, as we're going to make this as digestible as possible!

First stop, Public Key Cryptography 🔐👩‍🏫

👇

There are two main purposes of cryptography

- prove knowledge of a secret without revealing the secret
- prove authenticity of data (digital signature)

Cryptography is used extensively within Ethereum, and one place that users meet with cryptography is via Ethereum accounts.👩‍💻

Proof of ownership of Externally Owned Accounts (EOAs) is established through private keys and digital signatures.

The private keys are used almost everywhere within Ethereum during user interactions, and the Ethereum address of an EOA is derived from the private key.

In other words, the Ethereum address is the last 20 bytes of the hash of the public key controlling the account!

To prove you are the owner of an EOA, you need to sign a message with the corresponding private key🔑

This means only you have access to the funds on your account.

Imagine making a transaction sending 1 Ether to a contract to mint a new NFT.

Ethereum verified the digital signature you created (using the private key) against the corresponding account's public key hash (the address).

Neat, right? But why does it work? 🧐

Public key cryptography is based on mathematical functions that allow for unique public/private key pairs 🧮

Those pairs of keys have special properties, like ease of creation, but it's extremely hard (nearly impossible) to create a private key from its public key.

Having a private key makes it easy to create a public key, but just from knowing a public key, we cannot know which private key was used to create that public key.

That's why proper security of the crypto wallets is necessary 🦾

medium.com/immunefi/secur…

Public key cryptography is a cryptographic method that uses a key pair system.

The one key, called the private key, signs the message.

The other key, called the public key, verifies the signature.

This means, when we sign any message we basically create a digital signature.

This is done by hashing the message and running the ECDSA algorithm to combine the hash with the private key, producing a signature.

By doing this, any changes to the message will result in a different hash value.

Still with me?😵‍💫

Good, the hardest part is behind us 🤥

Just kidding, in the next thread we will dive deeper into the Digital Signatures and explain a bit the elliptic curve cryptography!

If you don't want to wait and want to dive deeper into the subject, we got you covered!

medium.com/immunefi/intro…

Next, we will learn about digital signatures in Ethereum and why they are cool.

If you liked this thread, please like and retweet to share the knowledge at #immunefischool and other Web3 communities.

The more you know, the safer the ecosystem!⛑

See ya in the next one!👋