Recently, I have been working on some interesting Bitcoin projects and I ran into the issue of converting my public key to a wallet address. I was initially using bitwasp/bitcoin module to achieve this but when I moved the project to a shared host it wasn't working because it needed a PHP Library my host will not allow me install because it is shared. Below is a solution to this. It follows the algorithm stated in Bitcoin documentation on step by step way of generating wallet address from public key.

<?php
/**
 * Class BitcoinUtils
 * @author Akinyele Olubodun
 */

class BitcoinUtils
{
    public function address_from_master_pub($public_key)
    {
        $step1= $this->hexStringToByteString($public_key);

        $step2=hash("sha256",$step1);

        $step3=hash('ripemd160', $this->hexStringToByteString($step2));

        $step4="00".$step3;

        $step5=hash("sha256", $this->hexStringToByteString($step4));

        $step6=hash("sha256", $this->hexStringToByteString($step5));

        $checksum=substr($step6,0,8);

        $step8 = $step4.$checksum;
        $step9 = "1".$this->bc_base58_encode($this->bc_hexdec($step8));

        return $step9;
    }

    function hexStringToByteString($hexString){

        $len=strlen($hexString);

        $byteString="";
        for ($i=0;$i<$len;$i=$i+2){
            $charnum=hexdec(substr($hexString,$i,2));
            $byteString.=chr($charnum);
        }

        return $byteString;
    }

    // BCmath version for huge numbers
    function bc_arb_encode($num, $basestr) {

        if( ! function_exists('bcadd') ) {
            Throw new Exception('You need the BCmath extension.');
        }

        $base = strlen($basestr);
        $rep = '';

        while( true ){
            if( strlen($num) < 2 ) {
                if( intval($num) <= 0 ) {
                    break;
                }
            }
            $rem = bcmod($num, $base);
            $rep = $basestr[intval($rem)] . $rep;
            $num = bcdiv(bcsub($num, $rem), $base);
        }
        return $rep;
    }

    function bc_arb_decode($num, $basestr) {

        if( ! function_exists('bcadd') ) {
            Throw new Exception('You need the BCmath extension.');
        }

        $base = strlen($basestr);
        $dec = '0';

        $num_arr = str_split((string)$num);
        $cnt = strlen($num);
        for($i=0; $i < $cnt; $i++) {
            $pos = strpos($basestr, $num_arr[$i]);
            if( $pos === false ) {
                Throw new Exception(sprintf('Unknown character %s at offset %d', $num_arr[$i], $i));
            }
            $dec = bcadd(bcmul($dec, $base), $pos);
        }
        return $dec;
    }


    // base 58 alias
    function bc_base58_encode($num) {
        return $this->bc_arb_encode($num, '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz');
    }
    function bc_base58_decode($num) {
        return $this->bc_arb_decode($num, '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz');
    }

    //hexdec with BCmath
    function bc_hexdec($num) {
        return $this->bc_arb_decode(strtolower($num), '0123456789abcdef');
    }
    function bc_dechex($num) {
        return $this->bc_arb_encode($num, '0123456789abcdef');
    }

}