RSA Data Security holds software patents on the RSA and RC5 algorithms. If there ciphers are used used inside the USA (and Japan?), you must contact RSA Data Security for licencing conditions. Their web page is http://www.rsa.com RC4 is a trademark of RSA Data Security, so use of this label should perhaps only me used with RSA Data Security's permission. The IDEA algorithm is patented by Ascom in Austria, France, Germany, Italy, Japan, Netherlands, Spain, Sweden, Switzerland, UK and the USA. They should be contacted if that algorithm is to be used, their web page is http://www.ascom.ch