Abstract
Some high-speed IPsec hardware systems need to support many thousands of security associations.
The cost of switching among different encryption keys can dramatically affect throughput, particularly
for the very common case of small packets. Three of the AES finalists (Rijndael, Serpent, and Twofish)
provide very high key agility, as is required for such applications. The other two candidates (MARS,
RC6) exhibit low key agility and may not be appropriate for use in such equipment.