[3] : hmac_crc - 5 - 36 solves : crypto: We're trying a new mac here at BKP---HMAC-CRC. The hmac (with our key) of "zupe zecret" is '0xa57d43a032feb286'.  What's the hmac of "BKPCTF"? https://s3.amazonaws.com/bostonkeyparty/2016/0c7433675c3c555afb77271d6a549bf5d941d2ab