LICENSE
This work is placed in the public domain.
Blowfish, GOST, and Rijndael are freely available for use.
HOWEVER
The IDEA algorithm is patented by Ascom and I believe MediaCrypt (a subsidiary) now holds the rights.
The RC6 algorithm is patented by RSA Security.
If you want to use the either algorithm for commercial purposes you should seek proper legal advice.
# IDEA LICENSE INFORMATION
#
# This software product contains the IDEA algorithm as described and claimed in
# US patent 5,214,703, EPO patent 0482154 (covering Austria, France, Germany,
# Italy, the Netherlands, Spain, Sweden, Switzerland, and the UK), and Japanese
# patent application 508119/1991, "Device for the conversion of a digital block
# and use of same" (hereinafter referred to as "the algorithm"). Any use of
# the algorithm for commercial purposes is thus subject to a license from Ascom
# Systec Ltd. of CH-5506 Maegenwil (Switzerland), being the patentee and sole
# owner of all rights, including the trademark IDEA.
#
# Commercial purposes shall mean any revenue generating purpose including but
# not limited to:
#
# i) Using the algorithm for company internal purposes (subject to a site
# license).
#
# ii) Incorporating the algorithm into any software and distributing such
# software and/or providing services relating thereto to others (subject to
# a product license).
#
# iii) Using a product containing the algorithm not covered by an IDEA license
# (subject to an end user license).
#
# All such end user license agreements are available exclusively from Ascom
# Systec Ltd and may be requested via the WWW at http://www.ascom.ch/systec or
# by email to idea@ascom.ch.
#
# Use other than for commercial purposes is strictly limited to non-revenue
# generating data transfer between private individuals. The use by government
# agencies, non-profit organizations, etc is considered as use for commercial
# purposes but may be subject to special conditions. Any misuse will be
# prosecuted.