Private key
A cryptographic secret that proves ownership of a cryptocurrency address and authorises transactions — analogous to the password and signature on your wallet combined.
Also known as: wallet key, signing key
Last reviewed: 1 June 2026
In cryptocurrency, a private key is a long string of letters and numbers (derived from the seed phrase) that mathematically corresponds to a public address. The private key is used to sign transactions, proving that the account holder is authorising a transfer. Unlike a bank transaction, signed crypto transactions cannot be reversed.
Losing your private key means losing permanent access to your funds. Sharing your private key — or the seed phrase from which it is derived — gives the recipient complete, irrevocable control over your wallet. This is why private keys should be generated and stored on devices you control, never transmitted online, and ideally stored in hardware wallets for significant holdings.
Fraudsters impersonating wallet support teams or using malware are the most common vectors for private key theft.