The Juniper SRX Services Gateway VPN must use AES encryption for the Internet Key Exchange (IKE) proposal to protect the confidentiality of remote access sessions.

Without confidentiality protection mechanisms, unauthorized individuals may gain access to sensitive information via a remote access session. The Advance Encryption Standard (AES) algorithm is critical to ensuring the privacy of the IKE session responsible for establishing the security association and key exchange for an IPsec tunnel. AES is used for encryption operations.

Remote access is access to DoD-non-public information systems by an authorized user (or an information system) communicating through an external, non-organization-controlled network. Remote access methods include broadband and wireless connections.

While there is much debate about the security and performance of AES, there is a consensus that AES is significantly more secure than other algorithms currently supported by IPsec implementations. AES is available in three key sizes: 128, 192, and 256 bits, versus the 56 bit DES. Therefore, there are approximately 1021 times more AES 128-bit keys than DES 56-bit keys. In addition, AES uses a block size of 128 bits—twice the size of DES or 3DES.