✉️ Verify Messages Haven't Been Tampered With
Learn how HMAC uses hash functions and secret keys to authenticate messages
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0 / 5 completed🔐 HMAC Authentication
How do blockchain APIs know a message truly comes from you AND hasn't been tampered with? Welcome to HMAC - the cryptographic guardian of API communications!
🚨 The API Security Problem
When you send a transaction to a blockchain API, two critical questions arise:
Did this request actually come from you, or is someone pretending to be you?
Has the message been altered in transit? Did "Send 1 BTC" become "Send 100 BTC"?
🎮 Compare: Vulnerable vs Secure
{amount: 10, to: "Alice"}
{amount: 1000, to: "Hacker"}
The server has no way to verify the message wasn't tampered with.
🤔 What Makes HMAC Special?
Both you and the server know the secret key. Attackers don't!
Combines your message with the secret key using SHA-256 (or similar)
Only someone with the secret key could create this signature
Changing even one character invalidates the entire signature
🌍 Where You've Seen HMAC Before
Binance, Coinbase, Kraken all use HMAC to secure API requests
Stripe, PayPal use HMAC for webhook verification
AWS, Google Cloud, Azure use HMAC-based request signing
RPC endpoints often require HMAC authentication