Wait, I can spend the same tokens twice?
Heyo,
Jules here, from Cyfrin.
We’ve been seeing a slow down in hacks in the last few months - which has us questioning whether it’s because: (a) our industry is doing a better job at security practices or (b) the market just didn’t have as much liquidity.
I guess with the recent spikes, we’re about to find out! Stay tuned.
This week
✍🏼 Blockchain’s double spending issue
📆 Cyfrin ecosystem updates
📚 Signature standards, replay attacks, and invariant testing
⭐️ Ecosystem rockstars
What is the double-spending problem?
The double-spending problem is an exploit in which the same token is used more than once, undermining the trust and security of financial transactions.
🤷🏻♀️ How does this happen?
Race attacks: Occur when an attacker exploits the time delay in transaction propagation across a decentralized blockchain network.
Finney Attacks: Attacker broadcasts a conflicting transaction which redirects the crypto to another address controlled by the attacker.
51% Attacks: Occur when a node controls the majority of the network’s hashing power, allowing it to rewrite transaction history and double spend tokens.
⚡️ How to make sure this doesn’t happen?
Use consensus mechanisms (PoW, PoS, PBFT) to reach agreement between nodes
Employ confirmation mechanisms of transactions
Make sure the blockchain has a transaction finality feature
Network monitoring for suspicious activity
Confirm if the Unspent Transaction Output (UTXO) has been spent
Education and awareness for users
Security and community vigilance
Preventing replay attacks
— Read more about the double-spending attack here!
This week at Cyfrin
👩🏻🎓 Cyfrin Updraft, the ultimate smart contract learning platform, made it to Coinmarketcap as one of the top resources for learning blockchain development!
🚀 Cyfrin Updraft has finally opened its doors to the public - because everyone should be able to learn smart contract development for free!
✨ Sneak peek - the Cyfrin brand is getting a lil update. Stay tuned!
Related articles
✍🏼 Everything you need to know about Ethereum signature standards.
⚡️ A replay attack happens when an attacker intercepts and manipulates data transmission over a network. Hint hint, they are connected to signatures!
👩🏻💻 Check out this video by Bloqarl going through how to create invariant tests for DeFi AMM smart contracts!
Ecosystem rockstars ⭐️
After supporting our community day after day, we’ve decided to onboard @eng.pips into our team as a Teacher Assistant. Find him on Cyfrin’s Discord and on each course’s Github!
Let us know what you thought of this new version of the newsletter here!
Sending lots of cyber love,
Jules 🤸🏻