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Abstract
Cryptography has been used to solve two major of security problems privacy and authentication problems. moreover .chaos is one of the recent sciences that have greet applications in the field of cryptography chaos can be in non-linear dynamical systems.
through this thesis crytosystems are used to achieve the privacy goal. two cipher algorithms are presented to meet the privacy requirements the first proposal toenforce the aging broken data encryption standard which is modified input/output data encryption standared.