问题：

[多选] Which of the following statements that describe Diffie Hellman Key exchange are correct？ （）

A .  A DH key exchange is an algorithm that utilizes asymmetric cryptographic keys.
B .  The DH key exchange is used to establish a shared secret over an insecure medium during an IPSec phase 1 exchange.
C .  The DH exchange is susceptible to man-in-the-middle attacks.
D .  The DH exchange is used to authenticate the peer device duringan IPSec phase 1 exchange.
E . A DH exchange provides Perfect Forward Secrecy （PFS）.