Bitcoin Core Wallet.dat Official

If you only have a backup from 2017 and haven't used the wallet since, you do not need to download the full blockchain to check your balance. Use a tool like pywallet or import the private keys into a lightweight wallet like Electrum.

The wallet.dat file contains:

If your PC has a keylogger or screen grabber, your encryption passphrase will be stolen the moment you type it. Never decrypt your wallet on a compromised machine. Bitcoin Core Wallet.dat

: In modern "Hierarchical Deterministic" (HD) wallets (default since 2018), it stores a master seed from which all other keys are derived, ensuring that a single backup can cover future addresses. 2. Technical Evolution and Structure If you only have a backup from 2017

Bitcoin Core supports wallet encryption via the encryptwallet RPC command. Encryption uses with a key derived from your passphrase using OpenSSL’s EVP_BytesToKey (with SHA-512). Never decrypt your wallet on a compromised machine