Function isChecksumWif

Checks if the checksum of an private key WIF is correct.

The private key WIF has 3 parts in this order:

• prefix: 1 byte
• private key: 32 bytes
• compressed: 1 byte for compressed public key (no byte for uncompressed)
• checksum: 4 bytes

checks:

• It must use version 0x80 in the prefix
• If the corresponding public key is compressed the byte 33 must be 0x01
• checksum = first 4 bytes of sha256(sha256(prefix + private key + compressed))

See Bitcoin WIF.