Wallet Import Format (WIF, also known as Wallet Export Format) is a way of encoding a private ECDSA key so as to make it easier to copy.

A testing suite is available for encoding and decoding of WIF at: http://gobittest.appspot.com/PrivateKey

• 1 Private key to WIF
• 2 WIF to private key
• 3 WIF checksum checking
• 4 External links
• 5 See also
• 6 References

Private key to WIF

1 – Take a private key

0C28FCA386C7A227600B2FE50B7CAE11EC86D3BF1FBE471BE89827E19D72AA1D 

2 – Add a 0x80 byte in front of it for mainnet addresses or 0xef for Testnet addresses. Also add a 0x01 byte at the end if the private key will correspond to a compressed public key

800C28FCA386C7A227600B2FE50B7CAE11EC86D3BF1FBE471BE89827E19D72AA1D 

3 – Perform SHA-256 hash on the extended key

8147786C4D15106333BF278D71DADAF1079EF2D2440A4DDE37D747DED5403592 

4 – Perform SHA-256 hash on result of SHA-256 hash

507A5B8DFED0FC6FE8801743720CEDEC06AA5C6FCA72B07C49964492FB98A714 

5 – Take the first 4 bytes of the second SHA-256 hash, this is the checksum^[1]

507A5B8D 

6 – Add the 4 checksum bytes from point 5 at the end of the extended key from point 2

800C28FCA386C7A227600B2FE50B7CAE11EC86D3BF1FBE471BE89827E19D72AA1D507A5B8D 

7 – Convert the result from a byte string into a base58 string using Base58Check encoding. This is the Wallet Import Format

5HueCGU8rMjxEXxiPuD5BDku4MkFqeZyd4dZ1jvhTVqvbTLvyTJ 

WIF to private key

1 – Take a Wallet Import Format string

5HueCGU8rMjxEXxiPuD5BDku4MkFqeZyd4dZ1jvhTVqvbTLvyTJ 

2 – Convert it to a byte string using Base58Check encoding

800C28FCA386C7A227600B2FE50B7CAE11EC86D3BF1FBE471BE89827E19D72AA1D507A5B8D 

3 – Drop the last 4 checksum bytes from the byte string

800C28FCA386C7A227600B2FE50B7CAE11EC86D3BF1FBE471BE89827E19D72AA1D 

4 – Drop the first byte (it should be 0x80). If the private key corresponded to a compressed public key, also drop the last byte (it should be 0x01). If it corresponded to a compressed public key, the WIF string will have started with K or L instead of 5 (or c instead of 9 on testnet). This is the private key^[2].

0C28FCA386C7A227600B2FE50B7CAE11EC86D3BF1FBE471BE89827E19D72AA1D 

WIF checksum checking

1 – Take the Wallet Import Format string

5HueCGU8rMjxEXxiPuD5BDku4MkFqeZyd4dZ1jvhTVqvbTLvyTJ 

2 – Convert it to a byte string using

800C28FCA386C7A227600B2FE50B7CAE11EC86D3BF1FBE471BE89827E19D72AA1D507A5B8D 

3 – Drop the last 4 checksum bytes from the byte string

800C28FCA386C7A227600B2FE50B7CAE11EC86D3BF1FBE471BE89827E19D72AA1D 

3 – Perform SHA-256 hash on the shortened string

8147786C4D15106333BF278D71DADAF1079EF2D2440A4DDE37D747DED5403592 

4 – Perform SHA-256 hash on result of SHA-256 hash

507A5B8DFED0FC6FE8801743720CEDEC06AA5C6FCA72B07C49964492FB98A714 

5 – Take the first 4 bytes of the second SHA-256 hash, this is the checksum

507A5B8D 

6 – Make sure it is the same, as the last 4 bytes from point 2

507A5B8D 

7 – If they are, and the byte string from point 2 starts with 0x80 (0xef for testnet addresses), then there is no error.

External links

• https://en.bitcoin.it/wiki/Wallet_import_format
• Wallet Import Format – Bitcoin Glossary – Bitcoin.org
• GitHub – bitcoinjs/wif: Bitcoin Wallet Import Format JS
• Bitcointalk
• WIF private key Forum

See Also on BitcoinWiki

• Mining
• CryptoNight
• ASIC
• Hardware wallet
• Cold storage

References

1. ↑ Wallet Import Format – Bitcoin Forum BitcoinTalk
2. ↑ Address – What roles of WIF(Wallet Import Format)? – Bitcoin Stack Exchange

Bitcoin Core documentation User documentation Alert system * Bitcoin Core compatible devices * Data directory * Fallback Nodes * How to import private keys in Bitcoin Core 0.7+ * Running Bitcoin * Transaction fees * Vocabulary Developer documentation Accounts explained * API calls list * API reference (JSON-RPC) * Block chain download * Dump format * getblocktemplate * List of address prefixes * Protocol documentation * Script * Technical background of version 1 Bitcoin addresses * Testnet * Transaction Malleability * Wallet import format History & theory Common Vulnerabilities and Exposures * DOS/STONED incident * Economic majority * Full node * Original Bitcoin client * Value overflow incident