==== EIP 55: Mixed-case checksum address encoding  ====
[[dido:public:ra:xapend:xapend.b_stds:defact:ethereum:eip| Return to Ethereum ERCs ]]

  : **Note**: The following is an excerpt from the official Ethereum site. It is provided here as a convenience and is not authoritative. Refer to the original document as the authoritative reference.

<table>
<caption>Data sheet for Mixed-case checksum address encoding </caption>
| Title                      | Mixed-case checksum address encoding  |
| Author                     | Vitalik Buterin, Alex Van de Sande |
| Status                     | Final |
| Created                    | 2016-01-14  |
| Description                | [[http://eips.ethereum.org/EIPS/eip-55]] |
| Specification              | [[http://eips.ethereum.org/EIPS/eip-55#Specification]] |
| Category                   | ERC |
</table>

=== Abstract === 
In English, convert the address to hex, but if the ith digit is a letter (ie. it’s one of ''abcdef'') print it in uppercase if the 4*ith bit of the hash of the lowercase hexadecimal address is 1 otherwise print it in lowercase.

=== Rationale === 
__Benefit__
     * Backwards compatible with many hex parsers that accept mixed case, allowing it to be easily introduced over time
    * Keeps the length at 40 characters
    *On average there will be 15 check bits per address, and the net probability that a randomly generated address if mistyped will accidentally pass a check is 0.0247%. This is a ~50x improvement over ICAP, but not as good as a 4-byte check code.