Walking Onions: Scaling Distribution of Information Safely in Anonymity Networks
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1 2 The first 10 years of Curve25519 Abstract: “This paper explains the design and implementation Daniel J. Bernstein of a high-security elliptic-curve- University of Illinois at Chicago & Diffie-Hellman function Technische Universiteit Eindhoven achieving record-setting speeds: e.g., 832457 Pentium III cycles 2005.05.19: Seminar talk; (with several side benefits: design+software close to done. free key compression, free key validation, and state-of-the-art 2005.09.15: Software online. timing-attack protection), 2005.09.20: Invited talk at ECC. more than twice as fast as other authors’ results at the same 2005.11.15: Paper online; conjectured security level (with submitted to PKC 2006. or without the side benefits).” 1 2 3 The first 10 years of Curve25519 Abstract: “This paper explains Elliptic-curve computations the design and implementation Daniel J. Bernstein of a high-security elliptic-curve- University of Illinois at Chicago & Diffie-Hellman function Technische Universiteit Eindhoven achieving record-setting speeds: e.g., 832457 Pentium III cycles 2005.05.19: Seminar talk; (with several side benefits: design+software close to done. free key compression, free key validation, and state-of-the-art 2005.09.15: Software online. timing-attack protection), 2005.09.20: Invited talk at ECC. more than twice as fast as other authors’ results at the same 2005.11.15: Paper online; conjectured security level (with submitted to PKC 2006. or without the side benefits).” 1 2 3 The first 10 years of Curve25519 Abstract: “This paper explains Elliptic-curve computations the design and implementation Daniel J. Bernstein of a high-security elliptic-curve- University of Illinois at Chicago & Diffie-Hellman function Technische Universiteit Eindhoven achieving record-setting speeds: e.g., 832457 Pentium III cycles 2005.05.19: Seminar talk; (with several side benefits: design+software close to done. -
Low-Cost Traffic Analysis Of
Low-Cost Traffic Analysis of Tor Steven J. Murdoch and George Danezis University of Cambridge, Computer Laboratory 15 JJ Thomson Avenue, Cambridge CB3 0FD United Kingdom {Steven.Murdoch,George.Danezis}@cl.cam.ac.uk Abstract Other systems, based on the idea of a mix, were de- veloped to carry low latency traffic. ISDN mixes [33] Tor is the second generation Onion Router, supporting propose a design that allows phone conversations to be the anonymous transport of TCP streams over the Inter- anonymised, and web-mixes [6] follow the same design pat- net. Its low latency makes it very suitable for common terns to anonymise web traffic. A service based on these tasks, such as web browsing, but insecure against traffic- ideas, the Java Anon Proxy (JAP)1 has been implemented analysis attacks by a global passive adversary. We present and is running at the University of Dresden. These ap- new traffic-analysis techniques that allow adversaries with proaches work in a synchronous fashion, which is not well only a partial view of the network to infer which nodes are adapted for the asynchronous nature of widely deployed being used to relay the anonymous streams and therefore TCP/IP networks [8]. greatly reduce the anonymity provided by Tor. Furthermore, The Onion Routing project has been working on stream- we show that otherwise unrelated streams can be linked level, low-latency, high-bandwidth anonymous communi- back to the same initiator. Our attack is feasible for the cations [35]. Their latest design and implementation, adversary anticipated by the Tor designers. Our theoreti- Tor [18], has many attractive features, including forward se- cal attacks are backed up by experiments performed on the curity and support for anonymous servers. -
Fast Elliptic Curve Cryptography in Openssl
Fast Elliptic Curve Cryptography in OpenSSL Emilia K¨asper1;2 1 Google 2 Katholieke Universiteit Leuven, ESAT/COSIC [email protected] Abstract. We present a 64-bit optimized implementation of the NIST and SECG-standardized elliptic curve P-224. Our implementation is fully integrated into OpenSSL 1.0.1: full TLS handshakes using a 1024-bit RSA certificate and ephemeral Elliptic Curve Diffie-Hellman key ex- change over P-224 now run at twice the speed of standard OpenSSL, while atomic elliptic curve operations are up to 4 times faster. In ad- dition, our implementation is immune to timing attacks|most notably, we show how to do small table look-ups in a cache-timing resistant way, allowing us to use precomputation. To put our results in context, we also discuss the various security-performance trade-offs available to TLS applications. Keywords: elliptic curve cryptography, OpenSSL, side-channel attacks, fast implementations 1 Introduction 1.1 Introduction to TLS Transport Layer Security (TLS), the successor to Secure Socket Layer (SSL), is a protocol for securing network communications. In its most common use, it is the \S" (standing for \Secure") in HTTPS. Two of the most popular open- source cryptographic libraries implementing SSL and TLS are OpenSSL [19] and Mozilla Network Security Services (NSS) [17]: OpenSSL is found in, e.g., the Apache-SSL secure web server, while NSS is used by Mozilla Firefox and Chrome web browsers, amongst others. TLS provides authentication between connecting parties, as well as encryp- tion of all transmitted content. Thus, before any application data is transmit- ted, peers perform authentication and key exchange in a TLS handshake. -
Crypto Projects That Might Not Suck
Crypto Projects that Might not Suck Steve Weis PrivateCore ! http://bit.ly/CryptoMightNotSuck #CryptoMightNotSuck Today’s Talk ! • Goal was to learn about new projects and who is working on them. ! • Projects marked with ☢ are experimental or are relatively new. ! • Tried to cite project owners or main contributors; sorry for omissions. ! Methodology • Unscientific survey of projects from Twitter and mailing lists ! • Excluded closed source projects & crypto currencies ! • Stats: • 1300 pageviews on submission form • 110 total nominations • 89 unique nominations • 32 mentioned today The People’s Choice • Open Whisper Systems: https://whispersystems.org/ • Moxie Marlinspike (@moxie) & open source community • Acquired by Twitter 2011 ! • TextSecure: Encrypt your texts and chat messages for Android • OTP-like forward security & Axolotl key racheting by @trevp__ • https://github.com/whispersystems/textsecure/ • RedPhone: Secure calling app for Android • ZRTP for key agreement, SRTP for call encryption • https://github.com/whispersystems/redphone/ Honorable Mention • ☢ Networking and Crypto Library (NaCl): http://nacl.cr.yp.to/ • Easy to use, high speed XSalsa20, Poly1305, Curve25519, etc • No dynamic memory allocation or data-dependent branches • DJ Bernstein (@hashbreaker), Tanja Lange (@hyperelliptic), Peter Schwabe (@cryptojedi) ! • ☢ libsodium: https://github.com/jedisct1/libsodium • Portable, cross-compatible NaCL • OpenDNS & Frank Denis (@jedisct1) The Old Standbys • Gnu Privacy Guard (GPG): https://www.gnupg.org/ • OpenSSH: http://www.openssh.com/ -
NUMS Elliptic Curves and Their Efficient Implementation
Fourℚ-based cryptography for high-performance and low-power applications Real World Cryptography Conference 2017 January 4-6, New York, USA Patrick Longa Microsoft Research Next-generation elliptic curves New IETF Standards • The Crypto Forum Research Group (CFRG) selected two elliptic curves: Bernstein’s Curve25519 and Hamburg’s Ed448-Goldilocks • RFC 7748: “Elliptic Curves for Security” (published on January 2016) • Curve details; generation • DH key exchange for both curves • Ongoing work: signature scheme • draft-irtf-cfrg-eddsa-08, “Edwards-curve Digital Signature Algorithm (EdDSA)” 1/23 Next-generation elliptic curves Farrel-Moriarity-Melkinov-Paterson [NIST ECC Workshop 2015]: “… the real motivation for work in CFRG is the better performance and side- channel resistance of new curves developed by academic cryptographers over the last decade.” Plus some additional requirements such as: • Rigidity in curve generation process. • Support for existing cryptographic algorithms. 2/23 Next-generation elliptic curves Farrel-Moriarity-Melkinov-Paterson [NIST ECC Workshop 2015]: “… the real motivation for work in CFRG is the better performance and side- channel resistance of new curves developed by academic cryptographers over the last decade.” Plus some additional requirements such as: • Rigidity in curve generation process. • Support for existing cryptographic algorithms. 2/23 State-of-the-art ECC: Fourℚ [Costello-L, ASIACRYPT 2015] • CM endomorphism [GLV01] and Frobenius (ℚ-curve) endomorphism [GLS09, Smi16, GI13] • Edwards form [Edw07] using efficient Edwards ℚ coordinates [BBJ+08, HCW+08] Four • Arithmetic over the Mersenne prime 푝 = 2127 −1 Features: • Support for secure implementations and top performance. • Uniqueness: only curve at the 128-bit security level with properties above. -
Privacy As Security
Privacy as Security Dr George Danezis Microsoft Research, Cambridge, UK. [email protected] Dr George Danezis Privacy as Security Key Thesis and Outline What is this talk about? I Explore the relations between notions of `privacy' and `traditional security'. I Key thesis: Privacy is better understood as security! How do we proceed? I Introduction to Privacy. I Revisiting security/privacy properties. Dr George Danezis Privacy as Security Scope Ground rules of this talk: I High-level: keep out the very technical details. Implementation issues, system specific, cryptography, statistics, standards. I Focus on technology and technology policy. There is also law, sociology, political science, and politics. I Look at privacy in the context of computer security Security properties, adversary models, security policies, . I A clear focus on the real world and its constraints. Dr George Danezis Privacy as Security Caricature of the debate: Security or Privacy \Privacy" important but. I . what about abuse and accountability? I . difficulties for Law Enforcement? I . copyright or libel? I (. what does a good, honest person has to hide anyway?) Established wisdom: I Need for a balance... I Control/limit dangerous technology (or research). I Result: Surveillance by design ! no privacy (often). Caricature conclusion: Security is most important! Dr George Danezis Privacy as Security Security and Privacy in Context A brief history of security, and where does privacy fit? I Early days (Pre-1970s): Security for the Government and Military. Focus on confidentiality properties. Some work on Tamper resistance, signal intelligence, . Keep secrets using computer security. I 70s to 90s: Commercial security and security for enterprises. -
Simple High-Level Code for Cryptographic Arithmetic - with Proofs, Without Compromises
Simple High-Level Code for Cryptographic Arithmetic - With Proofs, Without Compromises The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Erbsen, Andres et al. “Simple High-Level Code for Cryptographic Arithmetic - With Proofs, Without Compromises.” Proceedings - IEEE Symposium on Security and Privacy, May-2019 (May 2019) © 2019 The Author(s) As Published 10.1109/SP.2019.00005 Publisher Institute of Electrical and Electronics Engineers (IEEE) Version Author's final manuscript Citable link https://hdl.handle.net/1721.1/130000 Terms of Use Creative Commons Attribution-Noncommercial-Share Alike Detailed Terms http://creativecommons.org/licenses/by-nc-sa/4.0/ Simple High-Level Code For Cryptographic Arithmetic – With Proofs, Without Compromises Andres Erbsen Jade Philipoom Jason Gross Robert Sloan Adam Chlipala MIT CSAIL, Cambridge, MA, USA fandreser, jadep, [email protected], [email protected], [email protected] Abstract—We introduce a new approach for implementing where X25519 was the only arithmetic-based crypto primitive cryptographic arithmetic in short high-level code with machine- we need, now would be the time to declare victory and go checked proofs of functional correctness. We further demonstrate home. Yet most of the Internet still uses P-256, and the that simple partial evaluation is sufficient to transform such initial code into the fastest-known C code, breaking the decades- current proposals for post-quantum cryptosystems are far from old pattern that the only fast implementations are those whose Curve25519’s combination of performance and simplicity. instruction-level steps were written out by hand. -
The Double Ratchet Algorithm
The Double Ratchet Algorithm Trevor Perrin (editor) Moxie Marlinspike Revision 1, 2016-11-20 Contents 1. Introduction 3 2. Overview 3 2.1. KDF chains . 3 2.2. Symmetric-key ratchet . 5 2.3. Diffie-Hellman ratchet . 6 2.4. Double Ratchet . 13 2.6. Out-of-order messages . 17 3. Double Ratchet 18 3.1. External functions . 18 3.2. State variables . 19 3.3. Initialization . 19 3.4. Encrypting messages . 20 3.5. Decrypting messages . 20 4. Double Ratchet with header encryption 22 4.1. Overview . 22 4.2. External functions . 26 4.3. State variables . 26 4.4. Initialization . 26 4.5. Encrypting messages . 27 4.6. Decrypting messages . 28 5. Implementation considerations 29 5.1. Integration with X3DH . 29 5.2. Recommended cryptographic algorithms . 30 6. Security considerations 31 6.1. Secure deletion . 31 6.2. Recovery from compromise . 31 6.3. Cryptanalysis and ratchet public keys . 31 1 6.4. Deletion of skipped message keys . 32 6.5. Deferring new ratchet key generation . 32 6.6. Truncating authentication tags . 32 6.7. Implementation fingerprinting . 32 7. IPR 33 8. Acknowledgements 33 9. References 33 2 1. Introduction The Double Ratchet algorithm is used by two parties to exchange encrypted messages based on a shared secret key. Typically the parties will use some key agreement protocol (such as X3DH [1]) to agree on the shared secret key. Following this, the parties will use the Double Ratchet to send and receive encrypted messages. The parties derive new keys for every Double Ratchet message so that earlier keys cannot be calculated from later ones. -
Security Analysis of the Signal Protocol Student: Bc
ASSIGNMENT OF MASTER’S THESIS Title: Security Analysis of the Signal Protocol Student: Bc. Jan Rubín Supervisor: Ing. Josef Kokeš Study Programme: Informatics Study Branch: Computer Security Department: Department of Computer Systems Validity: Until the end of summer semester 2018/19 Instructions 1) Research the current instant messaging protocols, describe their properties, with a particular focus on security. 2) Describe the Signal protocol in detail, its usage, structure, and functionality. 3) Select parts of the protocol with a potential for security vulnerabilities. 4) Analyze these parts, particularly the adherence of their code to their documentation. 5) Discuss your findings. Formulate recommendations for the users. References Will be provided by the supervisor. prof. Ing. Róbert Lórencz, CSc. doc. RNDr. Ing. Marcel Jiřina, Ph.D. Head of Department Dean Prague January 27, 2018 Czech Technical University in Prague Faculty of Information Technology Department of Computer Systems Master’s thesis Security Analysis of the Signal Protocol Bc. Jan Rub´ın Supervisor: Ing. Josef Kokeˇs 1st May 2018 Acknowledgements First and foremost, I would like to express my sincere gratitude to my thesis supervisor, Ing. Josef Kokeˇs,for his guidance, engagement, extensive know- ledge, and willingness to meet at our countless consultations. I would also like to thank my brother, Tom´aˇsRub´ın,for proofreading my thesis. I cannot express enough gratitude towards my parents, Lenka and Jaroslav Rub´ınovi, who supported me both morally and financially through my whole studies. Last but not least, this thesis would not be possible without Anna who re- lentlessly supported me when I needed it most. Declaration I hereby declare that the presented thesis is my own work and that I have cited all sources of information in accordance with the Guideline for adhering to ethical principles when elaborating an academic final thesis. -
How Secure Is Textsecure?
How Secure is TextSecure? Tilman Frosch∗y, Christian Mainkay, Christoph Badery, Florian Bergsmay,Jorg¨ Schwenky, Thorsten Holzy ∗G DATA Advanced Analytics GmbH firstname.lastname @gdata.de f g yHorst Gortz¨ Institute for IT-Security Ruhr University Bochum firstname.lastname @rub.de f g Abstract—Instant Messaging has gained popularity by users without providing any kind of authentication. Today, many for both private and business communication as low-cost clients implement only client-to-server encryption via TLS, short message replacement on mobile devices. However, until although security mechanisms like Off the Record (OTR) recently, most mobile messaging apps did not protect confi- communication [3] or SCIMP [4] providing end-to-end con- dentiality or integrity of the messages. fidentiality and integrity are available. Press releases about mass surveillance performed by intelli- With the advent of smartphones, low-cost short-message gence services such as NSA and GCHQ motivated many people alternatives that use the data channel to communicate, to use alternative messaging solutions to preserve the security gained popularity. However, in the context of mobile ap- and privacy of their communication on the Internet. Initially plications, the assumption of classical instant messaging, fueled by Facebook’s acquisition of the hugely popular mobile for instance, that both parties are online at the time the messaging app WHATSAPP, alternatives claiming to provide conversation takes place, is no longer necessarily valid. secure communication experienced a significant increase of new Instead, the mobile context requires solutions that allow for users. asynchronous communication, where a party may be offline A messaging app that claims to provide secure instant for a prolonged time. -
Efficient Anonymous Group Communication
Efficient Anonymous Group Communication Vom Fachbereich Informatik der Technischen Universität Darmstadt genehmigte Dissertation zur Erlangung des akademischen Grades Doctor rerum naturalium (Dr. rer. nat.) Eingereicht von: Tim Grube geboren in Seeheim-Jugenheim Tag der Einreichung: 15. Mai 2018 Tag der Disputation: 10. Juli 2018 Erstreferent: Prof. Dr. Max Mühlhäuser Korreferent: Prof. Dr. Mathias Fischer Fachgebiet Telekooperation Fachbereich Informatik Technische Universität Darmstadt Hochschulkennziffer D 17 Darmstadt 2018 Tim Grube: Efficient Anonymous Group Communication, Darmstadt, Technische Universität Darmstadt Jahr der Veröffentlichung der Dissertation auf TUprints: 2018 Veröffentlicht unter CC BY-NC-ND 4.0 International https://creativecommons.org/licenses/ Things are only impossible until they’re not. — Captain Jean-Luc Picard, Star Trek: The Next Generation, “When The Bough Breaks” (1988) Dedicated to the loving memory of my father Volker Grube 1958 – 2007 ABSTRACT This dissertation addresses the important challenge of efficiency in anonymous communication. Solving this challenge is essen- tial to provide anonymity in group communication. Every exchanged message leaks metadata: this information de- scribes the communication itself with, among others, sender, re- cipients, frequency of the communication. While the law pro- tects this information, it is often published and misused with consequences for the participants of the communication—often consequences particular for the senders of information. Anonymous communication systems like Tor break the link be- tween senders and recipients of messages and diminish emerg- ing metadata. However, their design requires duplicating mes- sages for all recipients early, mostly at the sender itself. With that, the system has to handle an unnecessary burden of pro- cessing identical messages. This dissertation contributes a novel mechanism that establishes communication groups such that the message duplication is pushed as close to the recipients as pos- sible. -
Conditional Pseudonymity in Vehicular Ad Hoc Networks
Diplom Thesis Faculty of Engineering and Computer Science Ulm University Conditional Pseudonymity in Vehicular Ad Hoc Networks Florian Marcus Schaub presented on November 13, 2008 Supervisors Prof. Dr.-Ing. Michael Weber Dr. Frank Kargl Advisor Zhendong Ma Faculty of Engineering and Computer Science, Ulm University James-Franck-Ring, 89081 Ulm, Germany This thesis has been prepared in the summer semester 2008 as a requirement for the completion of the Diplom course Medieninformatik at Ulm University. Cover photo: Night blur by Mando Gomez http://www.mandolux.com Printed on November 9, 2008. Some rights reserved. This work is licensed under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License. To view a copy of this license, visit http://creativecommons.org/ licenses/by-nc-nd/3.0/de/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA. Computer Science is no more about computers than astronomy is about telescopes. Edsger W. Dijkstra Contents 1 Introduction 1 2 Problem Analysis 5 2.1 Characteristics of Vehicular Ad Hoc Networks . 5 2.2 Security and Privacy in Vehicular Ad Hoc Networks . 9 2.3 Conditional Pseudonymity . 14 2.4 Summary . 18 3 Requirements for Privacy in VANETs 19 3.1 Assumptions . 20 3.2 General VANET Requirements . 21 3.3 Pseudonym Requirements . 23 3.4 Authentication Requirements . 28 3.5 Summary . 30 4 Privacy in other Domains 33 4.1 Health Care . 34 4.2 E-Government . 39 4.3 E-Commerce . 43 4.4 Internet . 51 4.5 Ad Hoc Networks . 59 4.6 Summary .