> # Supported IPsec Transforms and Algorithms

> The component technologies implemented for IPsec include the following transforms:

> - Advanced Encrypted Standard (AES) is an encryption algorithm. It implements either 128 or 256 bits using Cipher Block Chaining (CBC) or counter mode.
> - Data Encryption Standard (DES) is used to encrypt packet data and implements the mandatory 56-bit DES-CBC. CBC requires an initialization vector (IV) to start encryption. The IV is explicitly given in the IPsec packet.
> - Triple DES (3DES) is a stronger form of DES with 168-bit encryption keys that allow sensitive information to be transmitted over untrusted networks.

> Note Cisco NX-OS images with strong encryption are subject to United States government export controls, and have a limited distribution. Images to be installed outside the United States require an export license. Customer orders might be denied or subject to delay due to United States government regulations. Contact your sales representative or distributor for more information, or send e-mail to export@cisco.com.

> - Message Digest 5 (MD5) is a hash algorithm with the HMAC variant. HMAC is a keyed hash variant used to authenticate data.
> - Secure Hash Algorithm (SHA-1) is a hash algorithm with the Hash Message Authentication Code (HMAC) variant.
> - AES-XCBC-MAC is a Message Authentication Code (MAC) using the AES algorithm.

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