Previous Module
Multi-Signature Demo

✍️ Your Digital Signature = Your Crypto Identity

Learn how private keys sign transactions and public keys verify them

🔐 Introduction to Digital Signatures

Digital signatures are the cryptographic foundation of blockchain security. They prove ownership, authenticate transactions, and enable trustless systems without intermediaries.

🎮 Interactive: Sign & Verify a Message

Experience how digital signatures work by signing a message with a private key and verifying it with a public key

🤔 Why Digital Signatures Matter

🔒

Authentication

Prove you are who you claim to be without revealing your identity. Your signature is mathematically linked to your public key.

🛡️

Integrity

Verify a message hasn't been altered. Even changing one character invalidates the signature completely.

⚖️

Non-Repudiation

Can't deny signing something. Only your private key could have created that signature. It's cryptographic proof.

🌐

Trustless Systems

No need for trusted third parties. Anyone can verify signatures mathematically without asking permission.

🔑 The Key Pair: Your Digital Identity

🔴
Private Key
  • • Secret number (256 bits)
  • • NEVER share with anyone
  • • Used to CREATE signatures
  • • Like your password + signature stamp
  • • Lost = Funds lost forever
🟢
Public Key
  • • Derived from private key
  • • Safe to share publicly
  • • Used to VERIFY signatures
  • • Like your username or address
  • • Can't reverse to get private key
Mathematical Relationship
Private Key → (One-way function) → Public Key
Easy to go forward, impossible to go backward

🌍 Real-World Impact

Bitcoin Transactions
Every Bitcoin transaction is signed with the sender's private key. Over 800 million transactions secured this way since 2009.
📜
Smart Contracts
Ethereum uses ECDSA signatures to authorize contract interactions. Billions in DeFi secured by digital signatures daily.
🏛️
Legal Documents
DocuSign and Adobe Sign use digital signatures for legally binding contracts. Over 1 billion documents signed digitally each year.

⚡ Quick Facts

2^256
Possible private keys (more than atoms in universe)
<1 sec
Time to create or verify a signature
$1T+
Crypto assets secured by digital signatures