Base 58

Base 58 is an encoding system that converts binary data into a character string consisting of a specific set of 58 characters. In particular, base 58 generally uses the 62 alphanumeric characters (26 lowercase letters + 26 uppercase letters + 10 digits) but removing 0 (zero), O (uppercase letter o), I (letter i uppercase) and l (lowercase letter L) in order to limit potential reading errors (by a human or a machine).

The base 58 was created to code large integer numbers, like any base in arithmetic, it uses symbols for the digits. In base 58, by default, the 58 symbols are 123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz

The correspondance table for Base58 is

Encryption of a number is done by performing a change of basis.

To encrypt a message, it is necessary to first convert it into a large number, using an encoding table such as ASCII or Unicode.

The decryption of Base 58 consists of a conversion of the message considered into base 58.

If the expected result is a number then convert base 58 to base 10 to obtain an integer.

If the expected result is a message, then convert the base 58 to binary or hexadecimal and use the desired coding table (ASCII or Unicode) to obtain a plain message.

The message is composed of at most 58 distinct characters, and must not contain a digit 0 (zero), nor a letter I (capital i), nor a letter O (capital o) or letter l (lowercase L).

Base58 is commonly used in crypto applications, cryptocurrency wallet addresses (Bitcoin or Ripple) or URLs.

Any reference to Bitcoin or its inventor Satoshi Nakamoto or to any other cryptocurrency like Ripple is a clue.

The symbol alphabet used to code base 58 may be completely different from 123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz.

A classic variant is 123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ (uppercase and lowercase inverted, used by Flickr) but many other alphabets, including deranged alphabets can be used.