03

Understand custody

A wallet holds access—not coins.

15 articles in this rubric.

Basics · UTXOs and keys

Where Bitcoin exists

Why a balance is a sum of unspent outputs and a wallet holds keys rather than coins.

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Practical guide

How to choose a wallet without losing access

Mobile, desktop and hardware wallets: purpose, trade-offs and the rules of reliable backup.

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Key loss · 2013 → 2025

8,000 BTC beneath a landfill

A drive reached a landfill, but the decisive loss came earlier: the only usable copy of access disappeared.

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Compromise · June 13, 2011

The first major reported theft: 25,000 BTC

A backup existed but could not reverse a transfer after someone gained access to the live wallet.

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Bitcoin Core · 2025–2026

An Old wallet.dat Cannot Simply Be Opened

The end of BDB wallet loading and a rare migration bug show why recovery begins with copies.

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BTC interest accounts · Verified August 20, 2026

Bitcoin interest accounts: who pays the yield?

Why Bitcoin itself creates no yield, who receives control of the keys and what risks hide behind the familiar word “deposit.”

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Research · 2011–2015

Why a Phrase from Memory Made a Bad Wallet

The brainwallet experiment: when a convenient human phrase became a predictable private key.

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BIP 39 · 2013

Twelve Words Are Not a Password

How BIP 39 turns randomness into a readable backup and why people should not invent the words.

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Custody · BTC or a product share

The Fund Holds BTC. What Does the Investor Hold?

Why a bitcoin exchange-traded product can follow Bitcoin’s price without giving its shareholder the same control as a private key.

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Custody · Coinbase 2025 / Trezor 2026

The Data Leaked, the Keys Did Not. Who Controls Your BTC?

Two incidents without stolen private keys reveal the difference between self-custody and an account with an intermediary.

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Bitcoin Depot · March 2026

50.903 BTC Left After Credentials Were Compromised

How access to a corporate system enabled an unauthorized BTC transfer without breaking Bitcoin—and why the entire path to signing must be protected.

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BTCPay Server · August 2026

The File That Became a Key: Theft Through BTCPay Server

How exposed authorization files gave attackers access to LND Lightning nodes and why version 2.4.2 required an urgent update.

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COLDCARD · July 2026

The Hardware Wallet That Generated Keys with Too Little Randomness

How a COLDCARD firmware defect reduced seed entropy and why updating the device does not repair a wallet that already exists.

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Bitcoin Core · Fix merged September 2, 2026

When a Wallet Name Becomes a Command

How a crafted wallet name could alter a walletnotify command and why RPC access should not imply access to the operating system.

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Bitcoin Core · Fix merged September 9, 2026

The Wallet Was Called Corrupted Even Though the Keys Were Still There

How a Bitcoin Core 31.0 compatibility check prevented some Miniscript descriptor wallets from loading—and why a corruption warning does not always mean lost coins.

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