Encrypted private key -> QR code

1. Steps to DECODE/ENCODE the WIF key

Private keys in Wallet Import Format (WIF) follow the following structure when base 58 is decoded:

• The first byte (0x80) indicates the network type, in this case the default network. (uint8_t)
• The next 32 bytes (0x9172e8eec99f144f72eca9a568759580edadb2cfd154857f07e657569493bc44) are the private key. (uint8_t(32))
• The next byte (0x01) is the compression flag. (boolean)
• The next 4 bytes (0x4739a585) are the checksum of all previous data. The checksum used is SHA256d. (uint8_t(4))

Checksum generation example:

HASH1 = SHA256(80 || 9172e8eec99f144f72eca9a568759580edadb2cfd154857f07e657569493bc44 || 01) (Bytes concatenation)
HASH1 = SHA256(809172e8eec99f144f72eca9a568759580edadb2cfd154857f07e657569493bc4401)
HASH1 = dd777204043c893da5d679703cacd9b7043e11b9b4f7311572759f5902e609cb

HASH2 = SHA256(dd777204043c893da5d679703cacd9b7043e11b9b4f7311572759f5902e609cb)
HASH2 = 4739a585c71b269803c5b5322f30fe01386e705ea8f775b08f6d2c0476d35c97

CHECKSUM = 4739a585

All hashes were performed using https://emn178.github.io/online-tools/sha256.html (hex option).

You can now encode/decode WIF keys.

memo: To encode into the WIF structure, the above data must be converted to base58 format. So to decode the WIF key you need to convert the base58 data into bytes as written above.

2. Partial problem solved (QrCode generation)

You can now encode your private key into your wallet import format. Then you can create a QR code. For example (using the same keys used above):

WIF = Base58Encode(809172e8eec99f144f72eca9a568759580edadb2cfd154857f07e657569493bc44014739A585)
WIF = L26SjTSxuXTPTv58MfMErY1wiL46D3CqnqvzQj754yZs6RKkfaVi

QrCode generation using https://www.barcodesinc.com/generator/qr/. I typed L26SjTSxuXTPTv58MfMErY1wiL46D3CqnqvzQj754yZs6RKkfaVi And I got this:

3. Warning

• This step is useful if you have a 32-byte private key. Not when you have it. encrypted private key. The key must first be decrypted using the encryption algorithm that encrypted it. This is a delicate step.
• I have used many websites to encode/decode data. It was a private key that was not secure but was only used for educational purposes. I would not recommend doing the same with your actual private key. The solution is to use software. As others have suggested, there are many. I would definitely advise you to use Sparrow as it offers technical features.
• One of the websites used to learn more about WIF is https://learnmeabitcoin.com/technical/wif.