user40589: I'm trying to understand the Base 58 WIF number. While messing around with importing on blockchain I noticed that if you change the last five (or so) digits, it doesn't appear to affect which address is imported - 
i.e. i get the "This address is already present in the wallet" note.
Does anyone have any insight they could share about this?

user10377: A picture is worth a 1000 words. See Figure 6 from Chapter 4 of the Bitcoin Book. The last 4 bytes are used as a checksum for error checking. The version prefix is different for Bitcoin altcoin forks. See the 3rd column of this Table for versions used by various altcoins.

user23123: The last 4 bytes of the WIF format is a checksum. The details can be seen here: https://en.bitcoin.it/wiki/Wallet_import_format
That's approximately 5 characters of Base58 that are essentially redundant. This is so that errors in the WIF encoded private key can be detected easily. I believe some wallets will simply ignore the checksum if it's not correct.

40589: <p>I'm trying to understand the Base 58 WIF number. While messing around with importing on blockchain I noticed that if you change the last five (or so) digits, it doesn't appear to affect which address is imported - 
i.e. i get the "This address is already present in the wallet" note.
Does anyone have any insight they could share about this?</p>
 10377: <p>A picture is worth a 1000 words. See <code>Figure 6</code> from <a href="https://github.com/bitcoinbook/bitcoinbook/blob/first_edition/ch04.asciidoc" rel="nofollow">Chapter 4</a> of the <strong>Bitcoin Book</strong>. The last 4 bytes are used as a <em>checksum</em> for error checking. The <em>version</em> prefix is different for Bitcoin altcoin forks. See the 3rd column of this <a href="https://github.com/libbitcoin/libbitcoin/wiki/Altcoin-Version-Mappings#bip44-altcoin-version-mapping-table" rel="nofollow">Table</a> for versions used by various altcoins.</p>
 23123: <p>The last 4 bytes of the WIF format is a checksum. The details can be seen here: <a href="https://en.bitcoin.it/wiki/Wallet_import_format" rel="nofollow">https://en.bitcoin.it/wiki/Wallet_import_format</a></p>

<p>That's approximately 5 characters of Base58 that are essentially redundant. This is so that errors in the WIF encoded private key can be detected easily. I believe some wallets will simply ignore the checksum if it's not correct.</p>
