The total processing speed of microprocessors (based on clock rate and number of circuits) is doubling roughly every year. Today, a symmetric session key needs to be 100 bits long to be considered...

The total processing speed of microprocessors (based on clock rate and number of circuits) is doubling roughly every year. Today, a symmetric session key needs to be 100 bits long to be considered strong. How long will a symmetric session key have to be in 30 years to be considered strong? (Hint: Consider how much longer decryption takes if the key length is ­increased by a single bit.)