I've downloaded the Bitcoin client from https://bitcoin.org/en/download
I also downloaded the PGP signed file that shows the SHA256 file signatures: https://bitcoin.org/bin/bitcoin-core-0.12.1/SHA256SUMS.asc
How do I verify this PGP signed file? When I use the command "gpg --verify SHA256SUMS.asc", I get the message
gpg: Signature made Fri Apr 15 02:37:20 2016 EDT using RSA key ID 36C2E964 gpg: Can't check signature: public key not found
Where do I get the public key?