RC2 technical questions
In a shameless attempt to move the discussion of RC2 into a more technical arena, here are some interesting questions to explore about RC2. --Bob Key expansion - How can you tell whether the permutation is based on some sequence of digits from PI? - What are the diffusion and avalanche properties of this permutation? - What are the linear characteristics of this permutation? - What are the properties of the compression function that maps 16 bits (bytes X and Y) to 8 bits (byte Z) via Z = P[X + Y]? - How does the length of the key influence the mixing of bits during each pass of the expansion algorithm? - Is this a non-linear feedback shift register over the field GF(256)? - If the first pass of expansion is viewed as a hash function that produces 40 or 128 bits out, what are its properties? Round Functions - What are the diffusion and avalanche properties of the two round functions? - What are the linear approximations and how good are they? - What characteristics can be preserved by the round function that performs rotations? - With what probability? - Does the amount of rotation influence the security? - What characteristics can be preserved by the round function that performs the data dependent selection of the expanded key? - With what probability? - Are there any "weak" keys? - Will the expansion algorithm produce them?
baldwin@rsa.com writes:
In a shameless attempt to move the discussion of RC2 into a more technical arena, here are some interesting questions to explore about RC2. --Bob
Key expansion - How can you tell whether the permutation is based on some sequence of digits from PI?
[long list of other good and interesting questions deleted] In a previous message, baldwin@rsa.com also wrote:
WARNING NOTICE ... in such source code under applicable law, including without limitation trade secret and copyright protection. In particular, RSA Data Security's RC2 (TM) symmetric block cipher source code has been illegally misappropriated and published. Please be advised that these acts, as well as any retransmission or use of this source code, is a violation of trade secret, copyright and various other state and federal laws. Any person or entity that acquires, discloses or uses this information without authorization or license to do so from RSA Data Security, Inc. is in violation of such laws and subject to applicable criminal and civil penalties, which may include monetary and punitive damages, payment of RSA's attorneys fees and other equitable relief.
Bob, I'm confused by these two messages, as a non-lawyer (but I realize you're also a non-lawyer). How can RSADSI, on the one hand, expect to be able to assert trade secret status over RC2 (with a warning to "...any person who acquires, discloses or uses this information...") while at the same time encouraging the world to examine and better understand the (illegally- published) RC2 code? To my lay mind, I cannot see how one can reconcile your two messages. I'm not trying to be cute or play lawyer. I'm honestly confused as to just what RSADSI's position here is. -matt
I'm confused by these two messages, as a non-lawyer (but I realize you're also a non-lawyer). How can RSADSI, on the one hand, expect to be able
Giving Bob the benefit of the doubt here, I'm assuming that he passed on the legal warning as a service to his employer, but he made his post talking about RC2's technical strengths as an individual, not speaking for his employer. -- Sameer Parekh Voice: 510-601-9777x3 Community ConneXion, Inc. FAX: 510-601-9734 The Internet Privacy Provider Dialin: 510-658-6376 http://www.c2.org/ (or login as "guest") sameer@c2.org
participants (3)
-
baldwin -
Matt Blaze -
sameer