Reference: IKE Encryption and Authentication Algorithms

Configuring a router device for the Symantec Web Security Service Firewall/VPN Access Method requires selecting Internet Key Exchange algorithms, which are used to create a channel over which IPsec Proposals negotiate and encrypt HTTP traffic.

The Web Security Service supports the following combinations, with following caveat.

Note: Symantec did not test every combination. Although the expectation is these are supported, Symantec recommends performing your own verification.