2020-03-16 16:07:39 -07:00
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# Hardware Wallets
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2020-02-26 10:04:28 -08:00
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2020-03-16 16:07:39 -07:00
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Signing a transaction requires a private key, but storing a private
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key on your personal computer or phone leaves it subject to theft.
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Adding a password to your key adds security, but many people prefer
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to take it a step further and move their private keys to a separate
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physical device called a *hardware wallet*. A hardware wallet is a
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small handheld device that stores private keys and provides some
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interface for signing transactions.
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2020-02-26 10:04:28 -08:00
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2020-03-16 16:07:39 -07:00
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The Solana CLI has first class support for hardware wallets. Anywhere
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you use a keypair filepath (denoted as `<KEYPAIR>` in usage docs), you
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can pass a URL that uniquely identifies a keypair in a hardware
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wallet.
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2020-02-26 10:04:28 -08:00
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2020-03-16 16:07:39 -07:00
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## Supported Hardware Wallets
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2020-02-26 10:04:28 -08:00
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2020-03-16 16:07:39 -07:00
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The Solana CLI supports the following hardware wallets:
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- Ledger Nano S {% page-ref page="ledger.md" %}
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## Specify A Hardware Wallet Key
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Solana defines a format for the URL protocol "usb://" to uniquely locate any
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Solana key on any hardware wallet connected to your computer.
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The URL has the following form, where square brackets denote optional fields:
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```text
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usb://<MANUFACTURER>[/<PRODUCT>[/<WALLET_KEY>]][?key=<DERIVATION_PATH>]
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```
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`PRODUCT` is optional and defaults to an auto-detected value. When using a Ledger
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Nano S, for example, it defaults to "nano-s" without quotes.
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`WALLET_KEY` is used to disambiguate multiple devices. Each device has a unique
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master key and from that key derives a separate unique key per app.
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`DERVIATION_PATH` is used to navigate to Solana keys within your hardware wallet.
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The path has the form `<ACCOUNT>[/<CHANGE>]`, where each `ACCOUNT` and `CHANGE`
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are positive integers.
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All derivation paths implicitly include the prefix `44'/501'`, which indicates
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the path follows the [BIP44 specifications](https://github.com/bitcoin/bips/blob/master/bip-0044.mediawiki)
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and that any derived keys are Solana keys (Coin type 501). The single quote
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indicates a "hardened" derivation. Because Solana uses Ed25519 keypairs, all
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derivations are hardened and therefore adding the quote is optional and
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unnecessary.
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For example, a fully qualified URL for a Ledger device might be:
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```text
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usb://ledger/nano-s/BsNsvfXqQTtJnagwFWdBS7FBXgnsK8VZ5CmuznN85swK?key=0/0
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```
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## Manage Multiple Hardware Wallets
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It is sometimes useful to sign a transaction with keys from multiple hardware
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wallets. Signing with multiple wallets requires *fully qualified USB URLs*.
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When the URL is not fully qualified, the Solana CLI will prompt you with
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the fully qualified URLs of all connected hardware wallets, and ask you to
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choose which wallet to use for each signature.
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Instead of using the interactive prompts, you can generate fully qualified
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URLs using the Solana CLI `resolve-signer` command. For example, try
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connecting a Ledger Nano-S to USB, unlock it with your pin, and running the
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following command:
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```text
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solana resolve-signer usb://ledger?key=0/0
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```
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You will see output similar to:
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```text
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usb://ledger/nano-s/BsNsvfXqQTtJnagwFWdBS7FBXgnsK8VZ5CmuznN85swK?key=0/0
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```
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but where `BsNsvfXqQTtJnagwFWdBS7FBXgnsK8VZ5CmuznN85swK` is your `WALLET_KEY`.
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With your fully qualified URL, you can connect multiple hardware wallets to
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the same computer and uniquely identify a keypair from any of them.
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