Proposal for "Encode_Base58_GMP"

Base58-GMP-PHP

High speed Base58 encoding using GMP with BigInt support

Base58 is a compact, safe, and readable encoding that uses
alpha-numeric characters only (unlike Base64) and limits
the alphabet to easily readable characters, avoiding
[0OIl] (unlike Base62).

Base58 is used by Flickr and others for URL shortening.

This implementation uses the GNU Multiple Precision
Arithmetic Library (GMP) (http://gmplib.org/) for high
speed encoding and decoding.

A md5_base58 function is also provided for digest
generation