tonybogdanov/alphabase

Base-Anything conversions for PHP

v1.0.1 2021-12-10 10:11 UTC

Requires

• php-64bit: ^7.4
• ext-bcmath: *
• ext-json: *

Requires (Dev)

• phpunit/phpunit: ^9.5
• symfony/var-dumper: ^5.4

MIT

• Tony Bogdanov

README

Installation

composer require tonybogdanov/alphabase:^1.0

Usage

Pass the string you want to convert as first argument, the alphabet (a string of unique characters) of the input as second argument, and the alphabet of the output as third argument.

The conversion expects all input characters to be found within the input alphabet and will convert them into characters found within the output alphabet.

If your input alphabet contains 32 characters and your output one contains 64, you are essentially converting from base32 into base64.

Keep in mind that the conversions here have nothing to do with standard algorithms like base64, and so are not interchangeable.

// qett
echo \TonyBogdanov\Alphabase\Converter::convert( 'abacab', 'abc', 'qwerty' );

// abacab
echo \TonyBogdanov\Alphabase\Converter::convert( 'qett', 'qwerty', 'abc' );

Caveat

It is not possible to unambiguously convert between bases without considering a special / padding character. Doing so, however, will force you to use a set of characters as your input alphabet + an extra padding character outside the alphabet, which will then make it impossible to convert from base256, since there will be no ASCII character available to use as padding.

To fix this issue the package will assume the very first character of each alphabet as the padding character. When a padding character is found at the beginning of your input string, it will be directly translated into the padding character of your output alphabet 1:1 without any conversion. This is only valid for the beginning of your input up until the very first occurrence of any other character. After that point the padding character will be converted like the rest.

This effect means you will lose the compressive capabilities of conversions like base32 to base128 for example, so keep that in mind.

A good consideration in regard to this is to always pick your alphabets such that the very first (padding) character is always one that has the lowest chance of being found in input strings, or at least in their beginning.