Private Key
A private key is the secret number that proves ownership of a crypto address and signs its transactions. Whoever has it controls the funds.
What Is a Private Key?
A private key is a secret number, typically 256 bits long, from which a public key and an address are derived. Signing a transaction with the private key proves to the network that the owner of that address authorised it. Anyone who learns the key can sign in the owner's place, and a confirmed blockchain transaction cannot be reversed.
Modern wallets rarely show individual private keys. They derive many keys from one master seed (BIP32), which is written down as a recovery phrase. Backing up the phrase therefore backs up every key in the wallet.
Hardware wallets exist to keep private keys away from internet-connected devices: the keys are generated and used inside the device, and only signatures leave it.
A public key is a cryptographic key used to receive transactions in a blockchain. It is shared openly, while the corresponding private key remains confidential.
Read full definitionA blockchain is a shared, append-only record of transactions kept by many independent computers, so no single party can rewrite it.
Read full definitionBIP32 is a Bitcoin Improvement Proposal defining a standard for hierarchical deterministic (HD) wallets, allowing the generation of a tree of keys from a single seed phrase.
Read full definitionA mnemonic phrase is a set of words that stores a cryptocurrency wallet's private keys, allowing users to recover access if lost.
Read full definitionA hardware wallet is a dedicated device that keeps private keys offline and signs transactions internally, so the keys never reach an internet-connected computer or phone.
Read full definitionReal-World Examples
Example 1: A phishing site asks a user to "verify" their wallet by pasting a private key. Anyone holding that key can empty the address.
Example 2: A hardware wallet signs a Bitcoin transaction internally; the companion app receives the signature, never the key.
Bitcoin (BTC) is the first decentralized cryptocurrency, launched in 2009. It uses blockchain technology for secure, peer-to-peer digital transactions without intermediaries.
Read full definitionA companion app is a software application used to manage and interact with cryptocurrency wallets or blockchain networks, typically offering features like transactions and security controls.
Read full definitionReady to Choose a Secure Wallet?
Use our tools to find the right hardware wallet for your needs.