[多选题]42、 Which of the following are available authentication methods used between the Easy VPN Remote client and server for tunnel establishment? (Choose all that apply.)下面哪些是用于Easy VPN远程客户端和服务器之间，用于建立隧道的可用的验证方法?(选择所有满足条件的答案)
A. Pre-shared keys 预共享密钥
B. RSA SecurId
C. X.509 certificates X.509证书
D. RSA certificates RSA证书