Support for AES

Support for the AES was first added in Windows Vista. AES is a Federal Information Processing Standard (FIPS) encryption standard developed by the National Institute of Standards and Technology (NIST) that supports variable key lengths and that replaces Data Encryption Standard (DES) as the standard encryption algorithm for government and industry. For L2TP/ IPsec-based VPN connections, the following AES encryption levels are supported in Windows Vista and later versions:

• Main mode IPsec main mode supports AES 256- and 128-bit encryption using Elliptical Curve Diffie-Hellman (ECDH) with 384- and 256-bit encryption, respectively.
• Quick mode IPsec quick mode supports AES 128-bit and 3DES encryption when the encryption setting in the Advanced Security Settings properties of the VPN connection is either Optional Encryption or Require Encryption. IPsec quick mode supports AES 256-bit and 3DES encryption when the encryption setting inside the Advanced Security Settings properties is Maximum Strength Encryption.