It could happen for a wide range of reasons. Below you will find a 
few suggestions.
                            
                                - You don't have an internet connection (as you can imagine, a rare problem and can be verified quickly).
- You may have a DNS problem, that can't resolve pgp.mit.edu accordingly. Please check your DNS settings (pgp.mit.edu works best with 8.8.8.8 DNS Server).
- You may have a network issue, different from the above one, which is hard for us to help since it can be a myriad of things. For example: DNS caching.
- You may have a clock/time issue.
- You may have something blocking your communication with mit.edu server, for instance: a firewall.
- If you're connected through a VPN, try to temporarily disable it and run strap.sh again.
                            After testing all the items described above if you still have problems using 
strap.sh, try the options below:
                            1
st option:
                            
# rm -rf /etc/pacman.d/gnupg
                            # pacman-key --init
                            # pacman-key --populate archlinux blackarch
                            # pacman-key --update --keyserver keyserver.ubuntu.com
                            2
nd option:
                            You could try to change to pgp.mit.edu's IP address using the following command:
                            
# curl -O https://blackarch.org/strap.sh
                            # chmod +x strap.sh
                            # sha1sum strap.sh: it should match with the information on 
downloads
                            # sh strap.sh
                            3
rd option:
                            You could try to  temporarily switch to another mirror:
                            
$ sudoedit /etc/pacman.d/blackarch-mirrorlist
                            It's very important to follow the suggestions above as well as checking the Archlinux Wiki pages to assist you as needed. If you still encounter any problems, pay us a visit at 
#BlackArch.