Re: Ada & Encryption / Compression

[kilgallen@eisner.decus.org (Larry Kilgallen)]

In article <Pine.GSO.3.93.970305115055.7933B-100000@sky.net>, John Howard <jhoward@sky.net> writes:

> Forget about doing your own RSA encryption.

Ok, you got my attention.

> 1)  RSA is patented.  You'd have to wait for the patent to expire.

	a. comp.lang.ada has international circulation.  RSA is only
	   patented in the United States.  Even if the original poster
	   was in the United States (not always obvious from email
	   addresses) or planned to do the work in the United States
	   (totally unknown absent a specific statement), there are
	   many others who will read your comments who are not in the
	   United States.

	b. Contrary to what you imply, the fact that something is
	   patented does not prevent you from using it.  it means
	   that using it requires obtaining a license from the
	   holder of the patent or their authorized representative.
	   In the case of RSA, the patent holder (actually, assignee)
	   is the Massachusetts Institute of Technology and the
	   authorized representative for licenses is RSA Data Security
	   Incorporated in Redwood Shores California.  Their general
	   web address for a patent license is:

		http://www.rsa.com/rsa/contracts/PatLicAgree.html

	   but I notice it is down today.  Those interested in the
	   general range of charges for a license could certainly
	   contact RSA Data Security Incorporated by other means.

> 2)  RSA can't be implemented unless you know the two large prime numbers
>     it uses (which are a secret).

	c. The RSA algorithm can use any two large prime numbers,
	   and the numbers are made up by the person who will be
	   using the RSA algorithm (with the help of a computer).

>                                    As of a year ago, RSA was still not
>     reported as cracked to reveal the two primes.  Presumably many skilled 
>     researchers have tried to crack RSA.

	d. That is the good part, unless the original poster said
	   his goal was to _break_ RSA.  When people say they are
	   going to _use_ RSA, they generally mean they are going
	   to make up their own prime numbers and take advantage
	   of the fact that there are no easy methods of breaking
	   RSA.  "Easy" is related to the size of the prime numbers
	   chosen, and a 129 digit (500 bits or so) challenge has
	   been broken so contemporary wisdom is to use 1024 bits
	   or so, except for the truly paranoid (the master key for
	   VISA as an example) where 2048 bits is used. Absent an
	   astounding breakthrough in factoring techniques, those
	   who discuss the adequacy of key size in relation to
	   Moore's Law (expanding computer potential) do so in terms
	   of how much longer it would take than the predicted remaining
	   life of the universe.  All such approaches presume massively
	   parallel efforts.

Sorry to go on so long, but I hate egregious misinformation.
Now I know how Robert Dewar feels with a typical day on c.l.a.

Larry Kilgallen