Wallet Import Format (WIF) is a standardized method for displaying Bitcoin private keys using the Base58Check encoding scheme. WIF format was standardized in order to allow all Bitcoin wallets to import and export private keys.
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The process of encoding a private key into WIF format is as follows. Raw private keys are simply large numbers, which are represented as bytes. WIF format adds a prefix byte (0x80 for mainnet and 0xef for testnet) so that almost all Bitcoin private keys begin with ‘5’ or a ‘K’ on mainnet. Next, a ‘0x01’ byte is added to the end of the private key if its corresponding public key should use compressed SEC format. Finally, a four byte double SHA-256 checksum is appended to the byte-encoded private key, in order to prevent typos or tampering. This byte string is then converted from bytes to Base58Check.
Below is an example of a private key displayed as a hexadecimal number and in WIF format.
Hex: 0x224b2d71866c35d3701f0fcdd7871cb191c2ae25068602759fcb9b59d9100e00
WIF: 5J5PZqvCe1uThJ3FZeUUFLCh2f*ck9pZhtEK4MzhNmugqTmxCdwE
