Congressional tax commission frets about crypto
http://www.wired.com/news/print_version/politics/story/20355.html?wnpg=all Some of the testimony warned of the dangers posed to governments by uncontrolled technology, a common complaint in the nation's capital. Specifically, presenters here at William and Mary College fretted that encryption technology, combined with the ability to buy and sell anywhere in the world, could allow consumers to skirt sales taxes. Maintaining taxes at current levels poses "an increasingly difficult problem for tax administrators as a result of new technologies," said Joseph Guttentag of the US Treasury Department. He warned that Americans may seek to evade high income taxes by moving online and offshore. "We are going to closely monitor the relationship of tax havens to electronic commerce... Encrypted [communications] create opportunities for untraceable transfer of assets and other activities that will hinder audits" Guttentag, who appeared in Treasury Secretary Robert Rubin's stead, is a senior adviser in the department's Office of Tax Policy and chairman of an Organization for Economic Cooperation and Development tax committee. He said the OECD should become more involved in eliminating "other forms of harmful tax competition."
Re: Bridge
There are 52! bridge hands, so a random hand has log2(56!) = 226 bits of entropy or 68 decimal digits worth. Are they generating that much entropy per hand now? If so, how? Generating that much entropy would be pointless. All that's needed is enough entropy to be unguessable in the seed and a cryptographically secure pseudo raandom number generator. Are you sure? A typical PRNG uses a 31 or 32 bit seed, which means that it could only generate 2^32 out of the 2^226 possible shuffles, a vanishingly small fraction of the total. (A few years back when the Unix PRNG only had a 16 bit seed, this was the basis of an extremely effective dictionary attack on "randomly" generated passwords.) Maybe the set of shuffles generated by a good PRNG are sufficiently many and well enough distributed through the total set that they're not amenable to exhaustive or statistical analysis, so it wouldn't matter, but this strikes me as exactly the kind of shortcut not to take when the issue at hand is the credibility of the shuffling process. Besides, by the time you've gathered 32 bits of true entropy, gathering another 195 bits isn't a lot more work. Regards, John Levine, [EMAIL PROTECTED], Primary Perpetrator of "The Internet for Dummies", Information Superhighwayman wanna-be, http://iecc.com/johnl, Sewer Commissioner Finger for PGP key, f'print = 3A 5B D0 3F D9 A0 6A A4 2D AC 1E 9E A6 36 A3 47
DSA sign only
Hi, I'm working with Elgamal public Key algorithm for encryption only. Now, I need to generate a signature with DSA (signature only). Do I have to calculate all the parameters (p, q, g, y, x ...) or is it possible to use parameters already calculate in Elgamal algorithm ? Best regards, Hans...
ElGamal without exponent reduction?
Hi, suppose we use an ElGamal-variant where we do not need to compute inverses modulo the group order. Such variants exists and they are explained in the Handbook of Cryptography, for instance, let G: generator a: secret value A: public value G^a and for the signature k: secret random value R: G^k and s = a h(m) + k g(R) mod n (*) where h is a hash-function, n is the group order, and g is a (public) mapping from the elements of the group to Z (the integers). The signature is (s, R). For the verification, check that G^s = A^h(m) R^g(R) holds. Now suppose that the reduction mod n in (*) is omitted. Except that the size of s would be larger, can anybody see whether this would be harmful? -- S. Hamdy| All primes are odd except 2, [EMAIL PROTECTED]| which is the oddest of all. | unsolicited commercial e-mail | D.E. Knuth is strictly not welcome |
RE: Bridge
-- From: Arnold G. Reinhold[SMTP:[EMAIL PROTECTED]] I am still not clear as to what the hard issues are. Nor am I. In fact, I can't help but wonder if this is a case where computers (which are effectively black boxes which users are asked to trust) are the wrong approach. How difficult would it be to build a mechanical shuffling machine, with enough randomness to produce a good shuffle? Even the best card magicians in the world have difficulty in performing more than a few perfect shuffles in a row. In the absence of a machine, let several neutral judges take turns shuffling the deck a few times. I realize that one of the goals is to give all the players in a tournament the same pack, but once again, non-computer procedures which are easily understandable, and which can be seen to be fair, are possible. After the initial shuffle, a set of decks can be collated to match a master deck pretty quickly, given pre-existing stacks of each card. (For example - let the master deck be used by a neutral judge or judges to arrange 52 stacks of cards down the length of a table - face down. Then let other neutral observers walk down the length of the table, picking one card from each stack, to build a deck.) All of this could be done well before the start of the match. Does this take any longer than what is currently done? After the decks are collated, let the teams select 'their' deck at random from the supply of pre-collated decks. If one is willing to stipulate no collusion between those who prepare the decks, and those who use them, a lot of procedures are fair and feasible. Computers are not always the appropriate solution. Peter Trei
Re: Bridge
Russell Nelson wrote: Plus, the source of the entropy and algorithm used to create the bridge hands merely need to be auditable. As long as the hands are based on some public source of entropy (e.g. the day's stock market) plus a letter publicly chosen by each of the participants (that's four bits of entropy on a good day), run through an OSI certified(tm) Open Source algorithm, everyone can calculate for themselves what the hands should be. It's almost a non-issue. But if anyone can calculate the hands before the tournament, or opposing player's hands during it, it's a disaster. Even if they can significantly improve their guessing, it is a serious problem.
