Wallet import format – Bitcoin Wiki

This page contains sample addresses and/or private keys. Do not send bitcoins to or import any sample keys; you will lose your money.

A wallet import format (WIF, also known as a 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

Private key to WIF

1. Take a private key.

   0C28FCA386C7A227600B2FE50B7CAE
_SAMPLE_PRIVATE_KEY_DO_NOT_IMPORT_
11EC86D3BF1FBE471BE89827E19D72AA1D

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.

   800C28FCA386C7A227600B2FE50B7C
_SAMPLE_PRIVATE_KEY_DO_NOT_IMPORT_
AE11EC86D3BF1FBE471BE89827E19D72AA1D

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.

   507A5B8D

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

   800C28FCA386C7A227600B2FE50B7CAE11EC8
_SAMPLE_PRIVATE_KEY_DO_NOT_IMPORT_
6D3BF1FBE471BE89827E19D72AA1D507A5B8D

7. Convert the result from a byte string into a base58 string using Base58Check encoding. This is the wallet import format (WIF).

   5HueCGU8rMjxEXxiPuD5BDk
_SAMPLE_PRIVATE_KEY_DO_NOT_IMPORT_
u4MkFqeZyd4dZ1jvhTVqvbTLvyTJ

WIF to private key

1. Take a wallet import format (WIF) string.

   5HueCGU8rMjxEXxiPuD5BDk
_SAMPLE_PRIVATE_KEY_DO_NOT_IMPORT_
u4MkFqeZyd4dZ1jvhTVqvbTLvyTJ

2. Convert it to a byte string using Base58Check encoding.

   800C28FCA386C7A227600B2FE50B7CAE11EC
_SAMPLE_PRIVATE_KEY_DO_NOT_IMPORT_
86D3BF1FBE471BE89827E19D72AA1D507A5B8D

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

   800C28FCA386C7A227600B2FE50B7CAE11EC86D3BF1FBE471BE89827E19D72AA1D

4. Drop the first byte (it should be 0x80, however legacy Electrum[1][2] or some SegWit vanity address generators[3] may use 0x81-0x87). 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 (or M, if it’s exported from legacy Electrum[1][2] etc[3]) instead of 5 (or c instead of 9 on testnet). This is the private key.

   0C28FCA386C7A227600B2FE50B7CAE1
_SAMPLE_PRIVATE_KEY_DO_NOT_IMPORT_
1EC86D3BF1FBE471BE89827E19D72AA1D

WIF checksum checking

1. Take the wallet import format (WIF) string.

   5HueCGU8rMjxEXxiPuD5BD
_SAMPLE_PRIVATE_KEY_DO_NOT_IMPORT_
ku4MkFqeZyd4dZ1jvhTVqvbTLvyTJ

2. Convert it to a byte string using Base58Check encoding.

   800C28FCA386C7A227600B2FE50B7CAE11E
_SAMPLE_PRIVATE_KEY_DO_NOT_IMPORT_
C86D3BF1FBE471BE89827E19D72AA1D507A5B8D

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

   800C28FCA386C7A227600B2FE50B7CAE11EC86D3BF1FBE471BE89827E19D72AA1D

4. Perform SHA-256 hash on the shortened string.

   8147786C4D15106333BF278D71DADAF1079EF2D2440A4DDE37D747DED5403592

5. Perform SHA-256 hash on result of SHA-256 hash.

   507A5B8DFED0FC6FE8801743720CEDEC06AA5C6FCA72B07C49964492FB98A714

6. Take the first 4 bytes of the second SHA-256 hash; this is the checksum.

   507A5B8D

7. Make sure it is the same as the last 4 bytes from point 2.

   507A5B8D

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

References

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