@Misc{RRSY01,
  author = 	 { Ronald L. Rivest and Matthew John Barton Robshaw and Raymond Mark Sidney and Yiqun Lisa Yin },
  title = 	 { Enchanced block ciphers with data-dependent rotations },
  howpublished = { U.S. Patent 6,269,163.  Issued July 31, 2001.  },
  date =         { 2001-07-31 },                  
  OPTyear = 	 { 2001 },
  OPTmonth = 	 { July 31, },
  urla =         { <a href="http://www.google.com/patents/US6269163">google-patent-page</a> },                  
  abstract =     { A plaintext message to be encrypted is segmented
                  into a number of words, e.g., four words stored in
                  registers A, B, C and D, and an integer
                  multiplication function is applied to a subset of
                  the words, e.g., to the two words in registers B and
                  D. The integer multiplication function may be a
                  quadratic function of the form .function.(x)=x(ax+b)
                  or other suitable function such as a higher-order
                  polynomial. The results of the integer
                  multiplication function are rotated by lg w bits,
                  where lg denotes log base 2 and w is the number of
                  bits in a given word, to generate a pair of
                  intermediate results t and u. An exclusive-or of
                  another word, e.g., the word in register A, and one
                  of the intermediate results, e.g., t, is rotated by
                  an amount determined by the other intermediate
                  result u. Similarly, an exclusive-or of the
                  remaining word in register D and the intermediate
                  result u is rotated by an amount determined by the
                  other intermediate result t. An element of a secret
                  key array is applied to each of these rotation results,
                  and the register contents are then transposed.  This 
                  process is repeated for a designated number of rounds
                  to generate a ciphertext message.  Pre-whitening and
                  post-whitening operations may be included to ensure
                  that the input or output does not reveal any 
                  internal information about any encryption round.
                  Corresponding decryption operations may be used
                  to decrypt the ciphertext message.
                 },                  
}