The Most Durable Bitcoin Cold Wallet

Everything you need to store your Bitcoin seed securely stamped on thick metal plates.

Compatible with Trezor, Ledger, Electrum and many others.

Latest blog posts

Can BIP-39 passphrase be cracked ?

In a recent post about BIP-39 I described how mnemonic sentences in the context of Bitcoin work and what makes them secure. 128 or 256 bit cryptography is considered secure and unbreakable now and for the foreseeable future. It’s the basis on which Bitcoin wallet security depends on. Can the same thing be said about […]

Extreme stress test of Coldbit Steel – will it survive?

Last year (2018) Jameson Lopp performed an extreme stress testing of a few Bitcoin metal wallets (BIP-39 seed backup). At that time Coldbit Steel was in the design phase and I took the first test results into consideration when designing it. This year I’m happy to announce that both Coldbit Steel and Coldbit Passphrase survived […]

BIP-39 basics. From randomness to mnemonic words.

Have you ever wondered how your Bitcoin wallet seed words (mnemonic words) guard access to your wallet funds and what makes such setup secure ? In this article we’ll dive into the basics of BIP-39 which describe what seed words are and how we can use them to backup our wallet keys in a recoverable […]

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