Avaya Configuring Data Encryption Services User Manual download pdf (Page 19)

Data Encryption Overview

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Message Digest 5 (MD5)

MD5 is a secure hash algorithm, and is a component in a number of IETF standard

protocols. MD5 operates on data of varying lengths, and produces from it a single

128-bit output called the digest. It is very difficult, given one message and its

digest, to fabricate another message that has the same digest.

This property enables MD5 to function like a checksum to detect errors in the

integrity of a message. When a message that contains a secret key is hashed, the

resulting digest also authenticates the origin of the message: only a source that

possesses the secret key could have calculated the digest. This technique is called

keyed MD5.

Nortel Networks encryption uses MD5 to:

• Authenticate the originator of the message, that is, to verify that the source

possesses the secret key.

• Verify the integrity of the DES keying material.

• Create new keys as part of a process that changes key values.

WAN Encryption Protocol (WEP)

WEP employs the DES algorithm, combined with MD5 and the appropriate key,

to encrypt data and add protocol information the receiver requires to identify the

data as encrypted. This encryption protocol is proprietary to Nortel Networks.

WEP begins by establishing the security of the link and verifying that both ends

have the same key. The two sides of the link issue connection request and

acknowledgment messages. They use keyed MD5 to exchange and authenticate

these messages. If the negotiation fails, data communication does not occur on

that circuit.

Security and Data Encryption

To use data encryption effectively, you must take precautions to protect the

security of your network equipment and the configuration process.

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Avaya Configuring Data Encryption Services User Manual Page 19