You want to build a hardware device to do block encryption in the cipher block chaining (CBC) mode using an algorithm stronger than DES. 3DES is a good candidate

You want to build a hardware device to do block encryption in the cipher block chaining (CBC) mode using an algorithm stronger than DES. 3DES is a good candidate. Figure 7.17 shows two possibilities, both of which follow from the definition of CBC. Which of the two would you choose and why:

1. For security?
2. For performance?

You must fully explain your justification and reasoning.