During a software development project review, the cryptographic engineer advises the project
manager that security can be greatly improved by significantly slowing down the runtime of a
hashing algorithm and increasing the entropy by passing the input and salt back during each
iteration. Which of the following BEST describes what the engineer is trying to achieve?

A.
Monoalphabetic cipher

B.
Confusion

C.
Root of trust

D.
Key stretching

E.
Diffusion