4.1 Local Simple Storage
Basics of Bitcoin Storage
Bitcoin storage fundamentally revolves around managing secret signing keys—your private cryptographic credentials that authorize transactions. Public information (like coin identity and value) resides on the blockchain and is always accessible, but private keys demand secure storage.
Key Management Goals
- Availability: Ensure keys are accessible when needed.
- Security: Prevent unauthorized access to coins.
- Convenience: Simplify key management without compromising safety.
Risks of Local Storage
- Device Failure: Lost or corrupted devices mean lost keys (and coins).
- Theft/Malware: Compromised devices expose keys to attackers.
👉 Best practices for securing local wallets
4.2 Cold vs. Hot Storage
Hot Storage
- Pros: Convenient for frequent transactions (e.g., mobile wallets).
- Cons: Vulnerable to online threats (malware, theft).
Cold Storage
- Pros: Offline security (e.g., hardware wallets, paper wallets).
- Cons: Less convenient for daily use.
Hierarchical Wallets
- How It Works: Cold devices generate addresses using cryptographic tricks (address generation info), while hot devices use these to create fresh addresses without exposing private keys.
- Security Benefit: Even if hot storage is breached, private keys remain secure.
4.3 Splitting and Sharing Keys
Secret Sharing (Shamir’s Scheme)
- Divide a private key into N shares, requiring K shares to reconstruct.
- Example: Split a key into 5 shares, with 3 needed to recover it. Losing 2 shares won’t compromise security.
Threshold Signatures
- Sign transactions without reconstructing the full key.
- Ideal for multi-device setups (e.g., desktop + phone).
Multisignature (Multisig) Wallets
- Use Bitcoin’s native scripting to require multiple signatures (e.g., 3-of-5 keys).
- Use Case: Business funds requiring collective control.
4.4 Online Wallets and Exchanges
Online Wallets
- Pros: Cross-device accessibility.
- Cons: Trust-dependent (provider could be hacked or malicious).
Bitcoin Exchanges
- Function: Trade between fiat and Bitcoin.
Risks:
- Bank Runs: Insufficient reserves.
- Fraud: Ponzi schemes (e.g., Mt. Gox).
- Hacks: Poor security practices.
Reserve Proofs
- How It Works: Exchanges cryptographically prove holdings (self-transactions) and liabilities (Merkle trees).
- Goal: Demonstrate solvency without revealing sensitive data.
FAQ Section
Q1: What’s the safest way to store Bitcoin?
A1: Use cold storage (e.g., hardware wallets) for long-term holdings and hot wallets only for small, daily amounts.
Q2: Can I recover lost private keys?
A2: No—lost keys mean permanently lost coins. Always back up keys securely (e.g., via secret sharing).
Q3: Are exchanges insured?
A3: Most aren’t. Unlike traditional banks, Bitcoin exchanges lack deposit insurance, making self-custody safer.
Q4: How do multisig wallets enhance security?
A4: They require multiple approvals, reducing single points of failure (e.g., 2-of-3 devices).