The Juniper SRX Services Gateway VPN must be configured to use Diffie-Hellman (DH) group 15 or higher.

Use of an approved DH algorithm ensures the Internet Key Exchange (IKE) (phase 1) proposal uses FIPS-validated key management techniques and processes in the production, storage, and control of private/secret cryptographic keys. The security of the DH key exchange is based on the difficulty of solving the discrete logarithm from which the key was derived. Hence, the larger the modulus, the more secure the generated key is considered to be. The DH group selected must have a minimum of a 3072-bit modulus to protect up to TOP SECRET.