Web of Trust Vs Certificate Authority
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Using Frankencerts for Automated Adversarial Testing of Certificate
Using Frankencerts for Automated Adversarial Testing of Certificate Validation in SSL/TLS Implementations Chad Brubaker ∗ y Suman Janay Baishakhi Rayz Sarfraz Khurshidy Vitaly Shmatikovy ∗Google yThe University of Texas at Austin zUniversity of California, Davis Abstract—Modern network security rests on the Secure Sock- many open-source implementations of SSL/TLS are available ets Layer (SSL) and Transport Layer Security (TLS) protocols. for developers who need to incorporate SSL/TLS into their Distributed systems, mobile and desktop applications, embedded software: OpenSSL, NSS, GnuTLS, CyaSSL, PolarSSL, Ma- devices, and all of secure Web rely on SSL/TLS for protection trixSSL, cryptlib, and several others. Several Web browsers against network attacks. This protection critically depends on include their own, proprietary implementations. whether SSL/TLS clients correctly validate X.509 certificates presented by servers during the SSL/TLS handshake protocol. In this paper, we focus on server authentication, which We design, implement, and apply the first methodology for is the only protection against man-in-the-middle and other large-scale testing of certificate validation logic in SSL/TLS server impersonation attacks, and thus essential for HTTPS implementations. Our first ingredient is “frankencerts,” synthetic and virtually any other application of SSL/TLS. Server authen- certificates that are randomly mutated from parts of real cer- tication in SSL/TLS depends entirely on a single step in the tificates and thus include unusual combinations of extensions handshake protocol. As part of its “Server Hello” message, and constraints. Our second ingredient is differential testing: if the server presents an X.509 certificate with its public key. -
Can We Trust Cryptographic Software? Cryptographic Flaws in GNU Privacy Guard V1.2.3
Can We Trust Cryptographic Software? Cryptographic Flaws in GNU Privacy Guard v1.2.3 Phong Q. Nguyen CNRS/Ecole´ normale sup´erieure D´epartement d’informatique 45 rue d’Ulm, 75230 Paris Cedex 05, France. [email protected] http://www.di.ens.fr/˜pnguyen Abstract. More and more software use cryptography. But how can one know if what is implemented is good cryptography? For proprietary soft- ware, one cannot say much unless one proceeds to reverse-engineering, and history tends to show that bad cryptography is much more frequent than good cryptography there. Open source software thus sounds like a good solution, but the fact that a source code can be read does not imply that it is actually read, especially by cryptography experts. In this paper, we illustrate this point by examining the case of a basic In- ternet application of cryptography: secure email. We analyze parts of thesourcecodeofthelatestversionofGNUPrivacyGuard(GnuPGor GPG), a free open source alternative to the famous PGP software, com- pliant with the OpenPGP standard, and included in most GNU/Linux distributions such as Debian, MandrakeSoft, Red Hat and SuSE. We ob- serve several cryptographic flaws in GPG v1.2.3. The most serious flaw has been present in GPG for almost four years: we show that as soon as one (GPG-generated) ElGamal signature of an arbitrary message is released, one can recover the signer’s private key in less than a second on a PC. As a consequence, ElGamal signatures and the so-called ElGamal sign+encrypt keys have recently been removed from GPG. -
Measuring the Rapid Growth of HSTS and HPKP Deployments
Measuring the Rapid Growth of HSTS and HPKP Deployments Ivan Petrov∗ Denis Peskov∗ Gregory Coard∗ Taejoong Chungy David Choffnesy Dave Levin∗ Bruce M. Maggsz Alan Mislovey Christo Wilsony ∗ University of Maryland yNortheastern University zDuke University & Akamai Technologies ABSTRACT version of the website, thereby exposing future commu- A basic man-in-the-middle attack to bypass HTTPS strips nication to the MiTM attacker, as well. Second, if an the “s” off of an “https://” URL, thereby forcing the client attacker is able to have a certificate created in someone to effectively downgrade to an insecure connection. To ad- else's name, the attacker can impersonate that victim dress such crude attacks, the HSTS (HTTP Strict Transport domain. Security) protocol was recently introduced, which instructs Both of these attacks completely sidestep the protec- clients to preemptively (or at time of first acquire) load a tions that TLS seeks to provide to its users. To address list of domains to whom to connect strictly via HTTPS. In a these concerns, two recent additions to HTTPS have similar vein, the HPKP (HTTP Public Key Pinning) protocol been introduced. We describe them in detail in Sec- has clients obtain a set of public keys; if in future visits to tion 2, but at a high level: the website the certificate chain does not include any of those • HTTP Strict Transport Security public keys, the client is supposed to reject the connection. (HSTS) [10] addresses SSL stripping attacks by Both HSTS and HPKP are relatively new additions to the informing clients which domains it should connect web’s PKI that have seen a sudden surge in deployment in to strictly over HTTPS (i.e., if presented with an the last couple of years (we observe an order of magnitude http URL to one of these domains, they should greater deployment than a 2015 study of HSTS/HPKP). -
Comptia Security+ 501
CompTIA Security+ 501 CompTIA Security+ SY0-501 Instructor: Ron Woerner, CISSP, CISM CompTIA Security+ Domain 6 – Cryptography & PKI 6.4 Given a scenario, implement public key infrastructure Cybrary - Ron Woerner 1 CompTIA Security+ 501 6.4 Public-Key Infrastructure (PKI) ● Components ● Types of certificates ○ Public / Private Key ○ User ○ Certificate ○ Root ○ CA ○ Wildcard ○ CRL ○ SAN ○ Code signing ● Concepts ○ Self-signed ○ Online vs Offline CA ○ Machine/computer ○ Stapling ○ Domain validation ○ Pinning ○ Trust model ● Certificate formats ○ Key escrow ○ Certificate chaining Public and Private Keys ● Encrypt a document with the recipient’s public key. Only their private key needs to be kept secret and only it can decrypt the message ● The sender’s private key is used to sign the message Cybrary - Ron Woerner 2 CompTIA Security+ 501 PKI Components Public Key Infrastructure ● Solves the issues with key management ● A set of roles, policies, and procedures needed to manage public- key(asymmetric) encryption ● The process of creating, managing, distributing, storing, using, and revoke keys and digital certificates. ● Public Key Infrastructure X.509 (PKIX) is the working group formed by the IETF to develop standards and models PKI PKI Components - Digital Certificate ● A digitally signed block of data used to prove the ownership of a public key issued by a Certificate Authority ● Includes ○ information about the key, ○ information about the identity of its owner (called the subject), ○ and the digital signature of an entity that has verified the certificate's contents (called the issuer) ● X.509 v3 standard defines the certificate formats and fields for public keys. Cybrary - Ron Woerner 3 CompTIA Security+ 501 Digital Certificate Components X.509 Certificate Types ● Root certificates: for root authorities. -
Security Analysis and Trust Models in Wireless Networks Lela Mirtskhulava
Security Analysis and Trust Models in Wireless Networks Lela Mirtskhulava [email protected] Department of Computer Sciences Faculty of Exact and Natural Sciences Iv. Javakhishvili Tbilisi State University University str., 13, Georgia In the given work, we analyse the serious weaknesses recently discovered in WPA2 (Wi-Fi Protected Access 2) in October 2017 and KRACK (Key Reinstallation Attack) attack on WPA2 announced by Computer Science Scientists. The KRACKs were introduced to abuse design flaws in cryptographic protocols to reinstall an already-in-use key. Several types of cryptographic Wi-Fi handshakes are affected by the attack. There are different forms of trust to address different types of network security problems and reduce risk in certain conditions. This paper explores the trust models applied by various cryptographic schemes: a) the web of trust employed by Pretty Good Privacy (PGP) where users using their own set of trusted public keys, b) Kerberos, a secret key distribution scheme using a trusted third party, c) certificates, which allow a set of trusted third parties to authenticate each other and, by implication, each other's users. Each of the above mentioned trust models differs in complexity, scope, scalability and general applicability. Which model of trust to apply in certain circumstances and types of wireless networks are discussed in the given paper. It describes the major security issues and their techniques of building trust model by monitoring network behavior. It is intended to use secure and faster cryptographic solution for Wi-Fi networks security by using an open source public-key NTRU cryptosystem that uses lattice-based cryptography. -
SIGMA: the 'Sign-And-Mac' Approach to Authenticated Diffie-Hellman and Its Use in the IKE Protocols
SIGMA: the `SIGn-and-MAc' Approach to Authenticated Diffie-Hellman and its Use in the IKE Protocols ∗ Hugo Krawczyky June 12, 2003 Abstract We present the SIGMA family of key-exchange protocols and the \SIGn-and-MAc" approach to authenticated Diffie-Hellman underlying its design. The SIGMA protocols provide perfect forward secrecy via a Diffie-Hellman exchange authenticated with digital signatures, and are specifically designed to ensure sound cryptographic key exchange while supporting a variety of features and trade-offs required in practical scenarios (such as optional identity protection and reduced number of protocol rounds). As a consequence, the SIGMA protocols are very well suited for use in actual applications and for standardized key exchange. In particular, SIGMA serves as the cryptographic basis for the signature-based modes of the standardized Internet Key Exchange (IKE) protocol (versions 1 and 2). This paper describes the design rationale behind the SIGMA approach and protocols, and points out to many subtleties surrounding the design of secure key-exchange protocols in general, and identity-protecting protocols in particular. We motivate the design of SIGMA by comparing it to other protocols, most notable the STS protocol and its variants. In particular, it is shown how SIGMA solves some of the security shortcomings found in previous protocols. ∗A shortened version of this paper appears in the proceedings of CRYPTO'03. For further information related to the SIGMA protocols see http://www.ee.technion.ac.il/~hugo/sigma.html yEE Department, Technion, Haifa, Israel, and IBM T.J. Watson Research Center. Email: [email protected] 1 Contents 1 Introduction 1 2 Preliminaries: On the Security of Key-Exchange Protocols 4 2.1 Overview of the security model and requirements . -
Analysis of SSL Certificate Reissues and Revocations in the Wake
Analysis of SSL Certificate Reissues and Revocations in the Wake of Heartbleed Liang Zhang David Choffnes Dave Levin Tudor Dumitra¸s Northeastern University Northeastern University University of Maryland University of Maryland [email protected] [email protected] [email protected] [email protected] Alan Mislove Aaron Schulman Christo Wilson Northeastern University Stanford University Northeastern University [email protected] [email protected] [email protected] ABSTRACT Categories and Subject Descriptors Central to the secure operation of a public key infrastruc- C.2.2 [Computer-Communication Networks]: Net- ture (PKI) is the ability to revoke certificates. While much work Protocols; C.2.3 [Computer-Communication Net- of users' security rests on this process taking place quickly, works]: Network Operations; E.3 [Data Encryption]: in practice, revocation typically requires a human to decide Public Key Cryptosystems, Standards to reissue a new certificate and revoke the old one. Thus, having a proper understanding of how often systems admin- istrators reissue and revoke certificates is crucial to under- Keywords standing the integrity of a PKI. Unfortunately, this is typi- Heartbleed; SSL; TLS; HTTPS; X.509; Certificates; Reissue; cally difficult to measure: while it is relatively easy to deter- Revocation; Extended validation mine when a certificate is revoked, it is difficult to determine whether and when an administrator should have revoked. In this paper, we use a recent widespread security vul- 1. INTRODUCTION nerability as a natural experiment. Publicly announced in Secure Sockets Layer (SSL) and Transport Layer Secu- April 2014, the Heartbleed OpenSSL bug, potentially (and rity (TLS)1 are the de-facto standards for securing Internet undetectably) revealed servers' private keys. -
An Empirical Analysis of Email Delivery Security
Neither Snow Nor Rain Nor MITM . An Empirical Analysis of Email Delivery Security Zakir Durumeric† David Adrian† Ariana Mirian† James Kasten† Elie Bursztein‡ Nicolas Lidzborski‡ Kurt Thomas‡ Vijay Eranti‡ Michael Bailey§ J. Alex Halderman† † University of Michigan ‡ Google, Inc. § University of Illinois, Urbana Champaign {zakir, davadria, amirian, jdkasten, jhalderm}@umich.edu {elieb, nlidz, kurtthomas, vijaye}@google.com [email protected] ABSTRACT tolerate unprotected communication at the expense of user security. The SMTP protocol is responsible for carrying some of users’ most Equally problematic, users face a medium that fails to alert clients intimate communication, but like other Internet protocols, authen- when messages traverse an insecure path and that lacks a mechanism tication and confidentiality were added only as an afterthought. In to enforce strict transport security. this work, we present the first report on global adoption rates of In this work, we measure the global adoption of SMTP security SMTP security extensions, including: STARTTLS, SPF, DKIM, and extensions and the resulting impact on end users. Our study draws DMARC. We present data from two perspectives: SMTP server from two unique perspectives: longitudinal SMTP connection logs configurations for the Alexa Top Million domains, and over a year spanning from January 2014 to April 2015 for Gmail, one of the of SMTP connections to and from Gmail. We find that the top mail world’s largest mail providers; and a snapshot of SMTP server providers (e.g., Gmail, Yahoo, -
Introduction À La Sécurité Des Systèmes D'informations
Université de Paris Saclay Polytech Paris Saclay – Département d’informatique Introduction à la sécurité des systèmes d’informations Document réalisé par : Polytech Paris Saclay Département d’informatique Université Paris Saclay Maison de l'Ingénieur Bâtiment 620 91405 Orsay Cedex Gilles Soufflet, Ingénieur Système Version janvier 2020 Université de Paris Saclay Sécurité informatique Polytech Paris Saclay – Département d’informatique Table des matières 1 Avant-propos ________________________________________________________________ 7 2 Notions de cryptographie _____________________________________________________ 10 2.1 Introduction _________________________________________________________________ 10 2.1.1 Principe de Kerckhoffs _______________________________________________________________ 10 2.2 Fonctions de hachage __________________________________________________________ 11 2.2.1 MD5 _____________________________________________________________________________ 11 2.2.2 SHA-1 ____________________________________________________________________________ 12 2.2.3 SHA-2 ____________________________________________________________________________ 12 2.2.4 SHA-3 ____________________________________________________________________________ 13 2.2.5 Whirpool __________________________________________________________________________ 13 2.3 Cryptographie à masque jetable _________________________________________________ 13 2.4 Cryptographie symétrique ou à clé secrète ________________________________________ 14 2.4.1 Chiffrement par bloc _________________________________________________________________ -
Analysis of SSL Certificate Reissues And
Analysis of SSL Certificate Reissues and Revocations in the Wake of Heartbleed Liang Zhang David Choffnes Dave Levin Tudor Dumitra¸s Northeastern University Northeastern University University of Maryland University of Maryland [email protected] [email protected] [email protected] [email protected] Alan Mislove Aaron Schulman Christo Wilson Northeastern University Stanford University Northeastern University [email protected] [email protected] [email protected] ABSTRACT Categories and Subject Descriptors Central to the secure operation of a public key infrastruc- C.2.2 [Computer-Communication Networks]: Net- ture (PKI) is the ability to revoke certificates. While much work Protocols; C.2.3 [Computer-Communication Net- of users' security rests on this process taking place quickly, works]: Network Operations; E.3 [Data Encryption]: in practice, revocation typically requires a human to decide Public Key Cryptosystems, Standards to reissue a new certificate and revoke the old one. Thus, having a proper understanding of how often systems admin- istrators reissue and revoke certificates is crucial to under- Keywords standing the integrity of a PKI. Unfortunately, this is typi- Heartbleed; SSL; TLS; HTTPS; X.509; Certificates; Reissue; cally difficult to measure: while it is relatively easy to deter- Revocation; Extended validation mine when a certificate is revoked, it is difficult to determine whether and when an administrator should have revoked. In this paper, we use a recent widespread security vul- 1. INTRODUCTION nerability as a natural experiment. Publicly announced in Secure Sockets Layer (SSL) and Transport Layer Secu- April 2014, the Heartbleed OpenSSL bug, potentially (and rity (TLS)1 are the de-facto standards for securing Internet undetectably) revealed servers' private keys. -
Security & Privacy for Mobile Phones
Security & Privacy FOR Mobile Phones Carybé, Lucas Helfstein July 4, 2017 Instituto DE Matemática E Estatística - USP What IS security? • That GRANTS THE INFORMATION YOU PROVIDE THE ASSURANCES above; • That ENSURES THAT EVERY INDIVIDUAL IN THIS SYSTEM KNOWS EACH other; • That TRIES TO KEEP THE ABOVE PROMISES forever. Security IS ... A System! • That ASSURES YOU THE INTEGRITY AND AUTHENTICITY OF AN INFORMATION AS WELL AS ITS authors; 1 • That ENSURES THAT EVERY INDIVIDUAL IN THIS SYSTEM KNOWS EACH other; • That TRIES TO KEEP THE ABOVE PROMISES forever. Security IS ... A System! • That ASSURES YOU THE INTEGRITY AND AUTHENTICITY OF AN INFORMATION AS WELL AS ITS authors; • That GRANTS THE INFORMATION YOU PROVIDE THE ASSURANCES above; 1 • That TRIES TO KEEP THE ABOVE PROMISES forever. Security IS ... A System! • That ASSURES YOU THE INTEGRITY AND AUTHENTICITY OF AN INFORMATION AS WELL AS ITS authors; • That GRANTS THE INFORMATION YOU PROVIDE THE ASSURANCES above; • That ENSURES THAT EVERY INDIVIDUAL IN THIS SYSTEM KNOWS EACH other; 1 Security IS ... A System! • That ASSURES YOU THE INTEGRITY AND AUTHENTICITY OF AN INFORMATION AS WELL AS ITS authors; • That GRANTS THE INFORMATION YOU PROVIDE THE ASSURANCES above; • That ENSURES THAT EVERY INDIVIDUAL IN THIS SYSTEM KNOWS EACH other; • That TRIES TO KEEP THE ABOVE PROMISES forever. 1 Security IS ... A System! Eve | | | Alice "Hi" <---------------> "Hi" Bob 2 Security IS ... Cryptography! Eve | | | Alice "Hi" <----"*****"------> "Hi" Bob 3 Security IS ... Impossible! The ONLY TRULY SECURE SYSTEM IS ONE THAT IS POWERED off, CAST IN A BLOCK OF CONCRETE AND SEALED IN A lead-lined ROOM WITH ARMED GUARDS - AND EVEN THEN I HAVE MY doubts. -
Certificate Transparency Using Blockchain
Certicate Transparency Using Blockchain D S V Madala1, Mahabir Prasad Jhanwar1, and Anupam Chattopadhyay2 1Department of Computer Science. Ashoka University, India 2School of Computer Science and Engineering. NTU, Singapore Abstract The security of web communication via the SSL/TLS protocols relies on safe distribu- tions of public keys associated with web domains in the form of X:509 certicates. Certicate authorities (CAs) are trusted third parties that issue these certicates. However, the CA ecosystem is fragile and prone to compromises. Starting with Google's Certicate Trans- parency project, a number of research works have recently looked at adding transparency for better CA accountability, eectively through public logs of all certicates issued by certica- tion authorities, to augment the current X:509 certicate validation process into SSL/TLS. In this paper, leveraging recent progress in blockchain technology, we propose a novel system, called CTB, that makes it impossible for a CA to issue a certicate for a domain without obtaining consent from the domain owner. We further make progress to equip CTB with certicate revocation mechanism. We implement CTB using IBM's Hyperledger Fabric blockchain platform. CTB's smart contract, written in Go, is provided for complete reference. 1 Introduction The overwhelming adoption of SSL/TLS (Secure Socket Layer/Transport Layer Security Proto- cols) [4, 33] for most HTTP trac has transformed the Internet into a communication platform with strong measures of condentiality and integrity. It is one