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[求助]常用的软件的具体加密算法
在 www.youtube.com 可以找到有人破解 PGP 某一版的教學影片,好像是 2006 年至 2008 年之間的,具體年代忘了,去搜就有。 |
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[求助]有没有熟悉GSM的A5.1或A5.2算法漏洞的?敬请留言,有事商量...
29 December 2009. GSM A5 Files Published on Cryptome 27 April 2000. Thanks to Adi Shamir. -------------------------------------------------------------------------------- This paper was presented at the Fast Software Encryption Workshop 2000, April 10-12, 2000, New York City. It supercedes an earlier version, "Real Time Cryptanalysis of the Alleged A5/1 on a PC (preliminary draft)," by Alex Biryukov and Adi Shamir, dated December 9, 1999. Original 18-page paper: http://cryptome.org/a5.ps (Postscript, 297K) Zipped Postscript: http://cryptome.org/a5.zip (104K) Real Time Cryptanalysis of A5/1 on a PC Alex Biryukov * Adi Shamir ** David Wagner *** Abstract. A5/1 is the strong version of the encryption algorithm used by about 130 million GSM customers in Europe to protect the over-the-air privacy of their cellular voice and data communication. The best published attacks against it require between 240 and 245 steps. This level of security makes it vulnerable to hardware-based attacks by large organizations, but not to software-based attacks on multiple targets by hackers. In this paper we describe new attacks on A5/1, which are based on subtle flaws in the tap structure of the registers, their noninvertible clocking mechanism, and their frequent resets. After a 248 parallelizable data preparation stage (which has to be carried out only once), the actual attacks can be carried out in real time on a single PC. The first attack requires the output of the A5/1 algorithm during the first two minutes of the conversation, and computes the key in about one second. The second attack requires the output of the A5/1 algorithm during about two seconds of the conversation, and computes the key in several minutes. The two attacks are related, but use diffrent types of time-memory tradeoff. The attacks were verified with actual implementations, except for the preprocessing stage which was extensively sampled rather than completely executed. REMARK: We based our attack on the version of the algorithm which was derived by reverse engineering an actual GSM telephone and published at http://www.scard.org. We would like to thank the GSM organization for graciously confiming to us the correctness of this unofficial description. In addition, we would like to stress that this paper considers the narrow issue of the cryptographic strength of A5/1, and not the broader issue of the practical security of fielded GSM systems, about which we make no claims. * Computer Science department, The Weizmann Institute, Rehovot 76100, Israel. ** Computer Science department, The Weizmann Institute, Rehovot 76100, Israel. *** Computer Science department, University of California, Berkeley CA 94720, USA. -------------------------------------------------------------------------------- 1 Introduction The over-the-air privacy of GSM telephone conversations is protected by the A5 stream cipher. This algorithm has two main variants: The stronger A5/1 version is used by about 130 million customers in Europe, while the weaker A5/2 version is used by another 100 million customers in other markets. The approximate design of A5/1 was leaked in 1994, and the exact design of both A5/1 and A5/2 was reverse engineered by Briceno from an actual GSM telephone in 1999 (see [3]). In this paper we develop two new cryptanalytic attacks on A5/1, in which a single PC can extract the conversation key in real time from a small amount of generated output. The attacks are related, but each one of them optimizes a different parameter: The first attack (called the biased birthday attack) requires two minutes of data and one second of processing time, whereas the second attack (called the the random subgraph attack) requires two seconds of data and several minutes of processing time. There are many possible choices of tradeo parameters in these attacks, and three of them are summarized in Table 1. Source from http://cryptome.org/a51-bsw.htm |
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[讨论]希望开展时空平衡算法(彩虹表及完美表)的学习和研究
A Time-Memory Trade-off Attack to Bit Search Generator and Its Variants |
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[讨论]希望开展时空平衡算法(彩虹表及完美表)的学习和研究
Variants of the Distinguished Point Method for Cryptanalytic Time Memory Trade-offs.ppt http://ccclab.csie.ntpu.edu.tw/ccclab_meeting/2009-12-14_Variants%20of%20the%20Distinguished%20Point%20Method%20for%20Cryptanalytic%20Time%20Memory%20Trade-offs.ppt |
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[讨论]希望开展时空平衡算法(彩虹表及完美表)的学习和研究
Cryptanalytic Time-Memory Trade-Off Cryptanalytic Time-Memory Trade-Off Project leader : Gildas Avoine Research Team : Information Security Group (GSI) Link : http://www.sites.uclouvain.be/security/ Description : Many cryptanalytic problems can be solved in theory using an exhaustive search in the key space, but are still hard to solve in practice because each new instance of the problem requires to restart the process from scratch. The basic idea of a time-memory trade-off is to carry out an exhaustive search once for all such that following instances of the problem become easier to solve. Thus, if there are N possible solutions to a given problem, a time-memory trade-off can solve it with T units of time and M units of memory. In the methods we are looking at, T is proportional to N2/M2 and a typical setting is T=M=N2/3. Cryptanalytic time-memory trade-offs have been introduced in 1980 by Hellman and applied to DES. Given a plaintext D and a ciphertext C, the problem consists in recovering the key K such that C=EK(D) where E is an encryption function assumed to follow the behavior of a random function. Encrypting D under all possible keys and storing each corresponding ciphertext allows for immediate cryptanalysis but needs N elements of memory. The idea of a time-memory trade-off is to find a trade-off between the exhaustive search and the exhaustive storage. For that, an exhaustive search is carried out once (precomputation) and only a subset of generated values is kept. In 2003, Oechslin introduced the trade-off based on rainbow tables and demonstrated the efficiency of his technique by recovering Windows passwords. In collaboration with Philippe Oechslin (Objectif Sécurité) and Pascal Junod (HEIG-Vd), we provided a formal analysis of rainbow tables and improved them using a new concept called checkpoints. We still work on the improvement of the time-memory trade-off using new approaches. | 30/07/2009 Source from http://www.uclouvain.be/281592.html |
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[讨论]希望开展时空平衡算法(彩虹表及完美表)的学习和研究
Space-Time Trade-Offs for Higher Radix Modular Multiplication.pdf (55.7 KB) |
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[讨论]希望开展时空平衡算法(彩虹表及完美表)的学习和研究
A Space-Time Trade-Off in Exhaustive Search Attacks on Stream Cipher.pdf (25.0 KB) |
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[推荐]Safengine 市场信心之作 , 10万求破解 ,牛人们快试试啊
霧裡看花,越看越花。 |
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[分享]真是利害。
「追女十大絕招」 科學家研究大公開! 更新日期:2010/01/28 12:47 楊茜雯 情人節快要來了,你還沒有男女朋友嗎?參考科學家的追愛十大撇步,包括看鬼片、坐雲霄飛車,招數有點幼稚,但背後其實有科學根據,因為冒險刺激情景中,雙方也因此患難見真情,另外幽默感、體貼也不可少,就連木村拓哉的新日劇,分析人的大腦運作,也教導觀眾,站在另一半的左側,對方會更容易愛上你。 情侶:「寶貝,我送你一個禮物,項鍊。」情侶:「哇,好漂亮喔。」 送鑽石項鍊,贏得女朋友一個擁抱,卻不見得能贏的她的心,想讓對方情不自禁深深愛上你,哪一招最有效?民眾:「看鬼片,就是刺激的感覺,雲霄飛車,男生應該坐幾百遍不會怕,然後保護女生。」 戀愛初學者的招數,聽起來有點幼稚,但背後卻有科學根據,美國史丹佛心理學家研究發現,運動、冒險中最患難見真難,進而引爆激情,另外約會適時接觸,象徵敞開心胸,最吃香的還是幽默感。民眾:「男生可以逗你笑,是一件很開心的事情,因為他會削水果給我吃,很體貼。」 體貼入微還要長保新鮮感,近一步肢體親密接觸,互相承諾;感情更加溫,就連站左邊、站右邊也有撇步。日劇「腦科學先生」:「人類善於判別男女的是用右腦,也就是說,想讓對方覺得你有男人味或女人味,要站在左邊。」 情侶:「他站我左邊啊。」記者:「你覺得今天比較愛他嗎?」情侶:「…,沒有啊。」 木村拓哉新日劇教大家站左邊,比較容易擄獲對方的心,即使沒效,也最好學這位男生的回答比較聰明。情侶:「我喜歡她,不是因為她站左右邊。」 Source from http://tw.news.yahoo.com/article/url/d/a/100128/8/1zlfo.html |
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求助,如何创建一个连续的文件
應該是你發帖時,點數就已經先扣除了。 |
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求助,如何创建一个连续的文件
你的問題可行。只是 speed rate 會降低,同時也會浪費 disk space。 最簡的方法如下: A way: 1) Format hard disk 讓這個 disk 成為 empty. 2) 把所有要寫入 disk 的 data , load 到 memory 裡。 (因為 memory 是足够的连续空间) 3) 然後把 data 從 memory 存回 disk 中. (這樣不就是连续性了!?) B way: 1) 先尋找一個空間大小 N bytes (假設 size N)。 2) 判斷 data < N ? 3) 若是,則直接 write;若否,則跳回 1) 重新找一個 N. |
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求助,如何创建一个连续的文件
這樣會有一點點的矛盾。 不通過 file system 來配置空間(應該說透過 OS 來 allocate disk space),怎麼能知道哪裡是 empty!? maybe lxcsyh 的意思是想自己處理 I/O ,而不用透過 OS 所提供的 I/O service。 透過 RAM 來回寫到 HardDisk 可能可以辦到。( not sure really) |
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