Problem 1 - mdanter/ecc v0.5.2 requires ext-gmp * -> the requested PHP extension gmp is missing from your system. code example

Example: Missing BC Math or GMP extension.

To install GMP for PHP7.0 on Ubuntu, 
run: sudo apt-get install php-gmp

Restart apache : sudo service apache2 restart

Make sure your php.ini contains the following: extension=php_gmp.so

To find out where your php.ini is located, run: php --ini