Level 2
Public Keys Explained
Your address for receiving cryptocurrency safely.
5 min read
A public key is a cryptographic code derived from your private key that can be shared safely with others. It's used to generate your wallet address (where people send you crypto) and to verify that transactions were signed by your private key.
Why This Matters
Understanding public keys helps you know what's safe to share and what isn't. Your wallet address (derived from your public key) is like your email address—you give it out to receive funds. Unlike your private key, sharing it doesn't put your funds at risk.
Simple Analogy
Think of a mailbox with a slot. Your wallet address (from your public key) is like the address on the mailbox—anyone can send mail to it. But only you have the key (private key) to open the mailbox and take mail out. Giving someone your address doesn't let them take your mail.
📊 Public Key vs Wallet Address
Private Key → [Cryptographic function] → Public Key (65 bytes) → [Hash + encode] → Wallet Address (shorter, starts with specific characters like '0x' for Ethereum or '1'/'3'/'bc1' for Bitcoin). The address is a compressed, checksummed version of your public key.
What You Can Safely Share
✓Wallet Address — Give this to receive payments (like an email address)
✓Public Key — Safe to share, but usually not needed (address is enough)
✗Private Key — NEVER share this with anyone
✗Seed Phrase — NEVER share this (it IS your private key)
How Public Keys Work in Transactions
1
You share your address
You give someone your wallet address (derived from public key) to receive payment.
2
They send crypto
The sender creates a transaction to your address and signs it with their private key.
3
Network verifies their signature
The network uses the sender's public key to verify they authorized the transaction.
4
Funds arrive at your address
The blockchain records the transfer to your address. Only your private key can move these funds.
Address Formats by Blockchain
| Blockchain | Address Format | Example Start |
|---|---|---|
| Bitcoin (Legacy) | 26-35 characters | 1... or 3... |
| Bitcoin (SegWit) | 42-62 characters | bc1... |
| Ethereum | 42 characters | 0x... |
| Solana | 32-44 characters | varies |
Address Safety Tips
- •Always double-check addresses before sending—transactions cannot be reversed
- •Copy-paste addresses carefully; malware can swap clipboard contents
- •Send a small test transaction first when using a new address
- •Verify the address matches the intended blockchain (ETH address won't work on Bitcoin)
- •QR codes are safer than manually typing addresses
Key Takeaways
- Public keys are derived from private keys using one-way math
- Wallet addresses are shortened versions of public keys
- Sharing your address is safe—it's how you receive funds
- Different blockchains have different address formats
- Always verify addresses carefully before sending crypto