Path: csiph.com!news.mixmin.net!aioe.org!.POSTED!not-for-mail From: bartekltg Newsgroups: comp.programming Subject: Re: Researches in quantum computing seem to progress only extremely slowly Date: Sat, 5 Sep 2015 01:24:39 +0200 Organization: Aioe.org NNTP Server Lines: 55 Message-ID: References: <34teuahtcltdi1mrq4gj95bu8gacjv112i@4ax.com> <0a1fua58g3o3sbe715rv0ugvvkkdd06lvr@4ax.com> <3vefualelae74fhsmcs0elv5us837istlh@4ax.com> <9unjuap4cjrt83f7pc6sqh3kf4ut3niv2k@4ax.com> <20150904132412.636@kylheku.com> NNTP-Posting-Host: 8yDXz2POMePMu60eIS0/Vw.user.speranza.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 X-Notice: Filtered by postfilter v. 0.8.2 Xref: csiph.com comp.programming:5814 On 04.09.2015 23:45, Mok-Kong Shen wrote: > > I don't yet see how your arguments above really refute my paradox. > Allow me thus to reformulate my issue as follows: > > If I use, say, dice throws to obtain a sequence of 128 bits, then, > assuming the dice are perfect, each bit of the sequence has 1.0 of > entropy, right? I use that as key of AES-128 in CTR mode to generate > 10000 bits. How much is the estimated entropy of each bit? I would > say that's anyway not larger than 128/10000. Am I right? If not, why? > If yes, how could one use bits of such low entropy value as keystream > to do good stream encryption (in comparison to Shannon's perfect > security case, which requires an entropy of 1.0 per bit)? I have a coin. I also have a long sequence of bits. "In Search of Lost Time", in French, encoded in utf8, then Harry Potter (all books, English, ASCII) and gcc source code (gibberish, gzip compressed). This sequence is known, I put it on webpage. While I'm waiting for lawsouit, I can toss a coin. If the coin lands on head, I will post the sequence on usenet. If it land on tail, I will post (NOT sequence), binary complement of the sequence. Every 1 as 0 and every 0 as 1. You are waiting for this sequence to see, if bit #546737536 of posted sequence is 1 or 0 to decided if you want a cake or an icecream. How much entropy is in bit #546737536? Is there any difference betwen bit #546737536 and tossing a coin? Tossing a coin has 1 bit of entropy. If you know the answer, second question. You decided, before the sequence was posted, that 546737536 a is ugly number and decided to look at bit #9999999 to decide whether or not buy a soda. How much entropy is in this bit? Less than a coin? And now, you remember that you still have to eat a dessert, so you look at bit #546737536. Is there more entropy? Or these two bits are _corelated_ and if you know #9999999, you known #546737536 without looking. There never be drinking a soda and eating a cake;-) bartekltg