Encrypt-It-Rite, a vendor of encryption software, sells a symmetric cipher which uses a 56-bit key. The company decides to conduct a "challenge" to crack an encrypted message using a brute-force approach. The average time to crack the message is found to be 2 hrs. As a result, Encrypt-It-Rite decides to increase the key length by 8 bits, from 56 to 64 bits. They then conduct another challenge. What average cracking time would be expected for the new, improved cipher? If Encrypt-It-Rite would like to increase average cracking time to at least 100 years, determine the minimal length of the key?