A seven-part security course for users who want to own their keys properly. Covers what exchanges actually hold, seed-phrase mechanics at depth, the multi-chain custody problem, what hardware wallets do and don't protect against, the 25th-word passphrase, the full attack-surface map, and a decision framework for your own custody plan.
Unpacks the difference between an IOU balance on an exchange and actual on-chain ownership, using concrete failures (FTX, Mt. Gox) to show what 'custodial' means in practice.
6 min read · beginner
Beyond the basics: how BIP-39 encodes entropy, how PBKDF2 and BIP-32/44 derive every key, what survives a device reset, and the recovery failure modes nobody warns you about.
9 min read · intermediate
Why a single BIP-32/44 seed unlocks accounts across Bitcoin, Ethereum, Solana, and 80+ other chains in Zelcore — and the practical implications for address reuse, chain-specific metadata, and protecting your one point of failure.
8 min read · intermediate
A clear-eyed threat model: what a secure element defends against, what it doesn't, and how to build self-custody habits that don't depend on false confidence.
8 min read · intermediate
How BIP-39 passphrases create a fully separate hidden wallet, why they're the strongest defence against physical seed-phrase theft, the brutal failure modes, and when this is genuinely worth the risk.
7 min read · intermediate
A practical catalogue of the top attacks on self-custody users — address poisoning, clipboard malware, fake wallet apps, and SIM swaps — with concrete mitigations for each.
9 min read · intermediate
A step-by-step framework for deciding where your assets actually live: thresholds for hot vs cold, when a passphrase or multi-sig layer is worth it, inheritance planning, and concrete example allocations.
8 min read · intermediate
