

IDEA (International Data Encryption Algorithm) 
  IDEA, unlike the other block cipher algorithms discussed in this section, is patented by the Swiss firm of Ascom. 
  In IDEA, for purposes of multiplication, a 16 bit word containing all zeroes is considered to represent the number 65,536; other numbers are represented in conventional unsigned notation, and multiplication is modulo the prime number 65,537. 
  Those that are multiplied in are replaced by their multiplicative inverse, modulo 65,537, in IDEA notation when used to change blocks directly, but those used to calculate the crossfooted Ffunctions are not changed. 
 www.quadibloc.com /crypto/co040302.htm (843 words) 
