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INTRODUCTION

Providing a way to check the integrity of information transmitted over or stored in an unreliable medium is a prime necessity in the world of open computing and communications. Mechanisms that provide such integrity checks based on a secret key are usually called message authentication codes (MACs). Typically, message authentication codes are used between two parties that share a secret key in order to authenticate information transmitted between these parties. This Standard defines a MAC that uses a cryptographic hash function in conjunction with a secret key. This mechanism is called HMAC [HMAC]. HMAC shall use an Approved cryptographic hash function [FIPS 180-3]. HMAC uses the secret key for the calculation and verification of the MACs.