anchor.diff:      gpg --import maxim.key && \
       curl -SLO https://nginx.org/keys/sb.key && \
       gpg --import sb.key && \
  +
  +    # Verify signature
  +    curl -SLO https://nginx.org/download/nginx-${NGINX_VERSION}.tar.gz.asc && \
       gpg nginx-${NGINX_VERSION}.tar.gz.asc
   
   RUN \
  
positive.code: 
  RUN \
      cd /tmp/build/nginx && \
      # Verify signature
      curl -SLO https://nginx.org/download/nginx-${NGINX_VERSION}.tar.gz.asc && \
      curl -SLO https://nginx.org/keys/nginx_signing.key && \
      gpg --import nginx_signing.key && \
      curl -SLO https://nginx.org/keys/aalexeev.key && \
  
negative.code:     # Download PHP
      curl -SLo php-${PHP_VERSION}.tar.gz http://ch1.php.net/get/php-${PHP_VERSION}.tar.gz/from/this/mirror
  
  RUN \
      cd /tmp/build/php/ && \
  
      # GPG keys from the release managers of PHP 7.0
      # Source https://secure.php.net/gpg-keys.php#gpg-7.0
      gpg --keyserver pgp.mit.edu/ --recv "1A4E 8B72 77C4 2E53 DBA9  C7B9 BCAA 30EA 9C0D 5763" && \
      gpg --keyserver pgp.mit.edu/ --recv "6E4F 6AB3 21FD C07F 2C33  2E3A C2BF 0BC4 33CF C8B3" && \
  
      # Verify signature
      curl -SLo php-${PHP_VERSION}.tar.gz.asc http://ch1.php.net/get/php-${PHP_VERSION}.tar.gz.asc/from/this/mirror && \
      gpg php-${PHP_VERSION}.tar.gz.asc
  
  RUN \
      cd /tmp/build/php && \
  