  Centera uses cryptographic hash functions as a means of addressing stored
objects, thus creating a new class of data storage referred to as CAS (content
addressed storage). Such hashing serves the useful function of providing a
means of uniquely identifying data and providing a global handle to that data,
referred to as the Content Address or CA. However, such a model begs the
question: how certain can one be that a given CA is indeed unique?
  In this paper we describe fundamental concepts of cryptographic hash
functions, such as collision resistance, pre-image resistance, and
second-preimage resistance. We then map these properties to the MD5 and SHA-256
hash algorithms, which are used to generate the Centera content address.
Finally, we present a proof of the collision resistance of the Centera Content
Address.
