Executive Summary
The Coinbase Chrome Extension gives users immediate and secure access to their cryptocurrency accounts directly in the browser. It focuses on three pillars: clear user control, robust local key protection, and frictionless interaction with decentralized apps. This refreshed document outlines a compact, actionable design — from install to transaction signing — and explains the security choices that make a browser extension both convenient and safe for everyday crypto use.
Why this matters
As web apps increasingly request wallet permissions, users need a familiar, transparent interface that reduces accidental exposure of keys and approvals. The extension should minimize permission scope, provide immediate context for every request, and make recovery understandable to novices while keeping advanced controls for power users.
Onboarding & Least Privilege
A short, three-step onboarding reduces cognitive load: (1) Create or restore wallet, (2) Back up mnemonic with an interactive verification step, (3) Choose a PIN for rapid unlock. The extension only asks for essential permissions — storage and activeTab — explaining each request in plain language. Optional features (network-switching, analytics) remain opt-in.
Usability details
PIN unlock for 5 minutes by default; full password required for exports and high-value approvals.
Show origin, asset, human-readable amount, and fee before signing.
One-click domain disconnect and easy removal of stored metadata.
Security Architecture
Keys are generated and encrypted locally using a strong KDF with high iterations and an AES-GCM cipher. Encrypted blobs stay in Chrome storage; critical operations happen in an isolated background script. The extension enforces strict Content Security Policy and prohibits dangerously broad permissions. Phishing heuristics flag suspicious domains and refuse silent approvals.
Recovery & Redundancy
Recovery uses BIP39 mnemonics with clear, guided instructions for safe backup — including recommended physical storage. For larger balances, users are guided to use a hardware wallet via a secure pairing flow rather than storing keys in the browser.
Developer & Release Notes
Developers should separate UI, business logic, and cryptography. Rely on audited libraries for crypto primitives, write unit tests for message handlers, and run nightly integration tests that simulate real RPC calls. Publish reproducible builds and a clear changelog. Staged rollouts and feature flags reduce blast radius for new changes.
Telemetry & Transparency
Any telemetry must be opt-in and privacy-preserving: aggregated, sampled, and never tied to private keys or addresses.
FAQ (Concise)
Is my seed online?
No — seeds are locally generated and encrypted. Export requires password confirmation.
How do I stay safe?
Verify domains before approving, keep an offline backup of your seed, and use a hardware wallet for large sums.