[REVS] Data Tastes Better Seasoned: Introducing the ASH Family of Hashing Algorithms

From: SecuriTeam (support_at_securiteam.com)
Date: 01/25/05

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      Data Tastes Better Seasoned: Introducing the ASH Family of Hashing
    Algorithms
    ------------------------------------------------------------------------

    SUMMARY

    Over the recent months it has become clear that the current generation of
    cryptographic hashing algorithms are insufficient to meet future needs.
    The ASH family of algorithms provides modifications to the existing SHA-2
    family.

    These modifications are designed with two main goals:
    1) Providing increased collision resistance
    2) Increasing mitigation of security risks post-collision. The unique
    public/private sections and salt/pepper design elements provide increased
    flexibility for a broad range of applications. The ASH family is a new
    generation of cryptographic hashing algorithms

    DETAILS

    Background:
    The late discoveries leave the United States' National Security Agency's
    (NSA) SHA-1/224/256/368/512 as the only mainstream algorithms for which
    cryptographers have yet to find collisions. These are also the only
    algorithms specified as the SHS (Secure Hash Standard) under FIPS (Federal
    Information Processing Standard) 180-2.[4]

    However, even these algorithms are showing weaknesses. In late August 2004
    the National Institute for Standards and Technology (NIST, the same body
    which releases the SHS and the FIPS) applauded the recent research and
    announced the phase out of SHA-1 by 2010[5]. Though these algorithms have
    remained strong and cryptanalysis on the newer algorithms have turned up
    no significant problems, it has become apparent that the current class of
    algorithm is rapidly becoming insufficient for future security needs.

    The ASH algorithms attempt to fill this need. Offering increased
    flexibility and security, the ASH algorithms are intended to provide
    modifications that will enhance overall security. Due to the security
    record of the SHA family and the availability of the new algorithms
    released in 2002, SHA-256 and SHA-512 have been chosen as the base
    algorithms for ASH-1 and ASH-2.

    Objectives:
    The ASH algorithms avoid the necessity to design new algorithms from the
    ground up. Instead, the ASH algorithms are based on an existing algorithm.
    For ASH-1 and ASH-2, algorithms in the SHA family have been selected. ASH
    is designed to treat the actual hash function as a black-box that can
    easily be changed as newer and improved hash functions are created. ASH
    reorders and modifies data as it is fed into the hash function, this
    results in increased security and offers improved mitigation of collisions
    when they do take place.

    The goal is to increase resistance, not provide an absolute solution to
    any particular problems as to do so would be impossible or infeasible.

    ASH's series of modifications are not SHA specific and can be applied to
    any iterative hashing function. For the first several algorithms, ASH is
    merely SHA with alterations to the datastream as it enters the hashing
    function. (Hence the similarity in the names of the algorithms.)

    However, the modifications increase the flexibility of the algorithms
    immeasurably. A pepper (explained later) is also used. The pepper allows
    for multiple dynamic sections to be generated. Each section can be
    verified to increase the security of the system. (This is discussed the
    the Secret Seasoning section.)

    Download Information:
    The paper can be found at:
    <http://xxx.lanl.gov.nyud.net:8090/pdf/cs.CR/0501038>
    http://xxx.lanl.gov.nyud.net:8090/pdf/cs.CR/0501038

    ADDITIONAL INFORMATION

    The original article can be found at:
    <http://xxx.lanl.gov.nyud.net:8090/abs/cs.CR/0501038>
    http://xxx.lanl.gov.nyud.net:8090/abs/cs.CR/0501038

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