A private key is a secret cryptographic value used to create digital signatures and authorize specific operations. In cryptocurrency systems, control over the corresponding private key generally means control over assets that can be spent or moved from associated addresses.

A private key is mathematically related to a public key. The public key can be used to verify signatures, while the private key must remain secret. Users should never disclose private keys or enter them into untrusted websites or applications.

Private keys and blockchains

The private key itself is normally not stored on the blockchain. Instead, the blockchain contains information that allows the network to verify signatures or determine the state associated with an address. When funds are sent, the wallet uses the private key to create a signature that the network verifies.

Modern wallets often do not require users to manage a separate private key for every address. In HD wallets, many keys can be derived from common root key material such as a seed phrase.

Private-key security is critical. Disclosure can allow another person to authorize valid transactions, while loss of the key without a usable backup can make the associated assets inaccessible.