Course
Custody & Security
How to hold crypto safely: wallets, keys and seed phrases, and the scams and habits that decide whether you keep it.
Beginner–Intermediate2 units · 9 lessons~17 min
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Syllabus
Unit 1
Wallets — Types & How to Use Them
Beginner4 lessons~9 minUnit 2
Security & Scams
Intermediate5 lessons~8 min
Cheat sheet
Wallets — Types & How to Use Them
- A wallet holds your keys, not your coins — the coins live on the blockchain.
- Hot wallets are convenient (online); cold/hardware wallets are safer for larger amounts (offline).
- Custodial = someone else holds your keys (e.g. an exchange); non-custodial = you hold them.
- A seed phrase (BIP39) is entropy encoded as words — it derives all your keys. Lose it and funds are gone forever; share it and funds are stolen.
- Always verify the recipient address and the network — wrong-network sends usually lose funds permanently.
Security & Scams
- In crypto you are the bank — there’s no fraud department to reverse a mistake.
- Never share your seed phrase with anyone, ever. Any “support” asking for it is a scam.
- Common attacks: phishing, seed-phrase theft, rug pulls, 51% attacks, SIM swaps, address poisoning, social engineering, reentrancy, flash-loan attacks, oracle manipulation.
- Defensive habits: hardware wallet for significant amounts, TOTP/FIDO2 2FA (not SMS), address verification, skepticism toward urgency.
- Organizational controls: multi-sig, approval workflows, address allow-listing, segregation of duties, out-of-band verification, RBAC, training drills, incident plans.