Keys in the Clouds: Auditable Multi-device Access to Cryptographic Credentials

Personal cryptographic keys are the foundation of many secure services, but storing these keys securely is a challenge, especially if they are used from multiple devices. Storing keys in a centralized location, like an Internet-accessible server, raises serious security concerns (e.g. server compromise). Hardware-based Trusted Execution Environments (TEEs) are a well-known solution for protecting sensitive data in untrusted environments, and are now becoming available on commodity server platforms. Although the idea of protecting keys using a server-side TEE is straight-forward, in this paper we validate this approach and show that it enables new desirable functionality. We describe the design, implementation, and evaluation of a TEE-based Cloud Key Store (CKS), an online service for securely generating, storing, and using personal cryptographic keys. Using remote attestation, users receive strong assurance about the behaviour of the CKS, and can authenticate themselves using passwords while avoiding typical risks of password-based authentication like password theft or phishing. In addition, this design allows users to i) define policy-based access controls for keys; ii) delegate keys to other CKS users for a specified time and/or a limited number of uses; and iii) audit all key usages via a secure audit log. We have implemented a proof of concept CKS using Intel SGX and integrated this into GnuPG on Linux and OpenKeychain on Android. Our CKS implementation performs approximately 6,000 signature operations per second on a single desktop PC. The latency is in the same order of magnitude as using locally-stored keys, and 20x faster than smart cards.Comment: Extended version of a paper to appear in the 3rd Workshop on Security, Privacy, and Identity Management in the Cloud (SECPID) 201

A Secure Mobile-based Authentication System

Financial information is extremely sensitive. Hence, electronic banking must provide a robust system to authenticate its customers and let them access their data remotely. On the other hand, such system must be usable, affordable, and portable.We propose a challengeresponse based one-time password (OTP) scheme that uses symmetric cryptography in combination with a hardware security module. The proposed protocol safeguards passwords from keyloggers and phishing attacks. Besides, this solution provides convenient mobility for users who want to bank online anytime and anywhere, not just from their own trusted computers.La informació financera és extremadament sensible. Per tant, la banca electrònica ha de proporcionar un sistema robust per autenticar als seus clients i fer-los accedir a les dades de forma remota. D'altra banda, aquest sistema ha de ser usable, accessible, i portàtil. Es proposa una resposta al desafiament basat en una contrasenya única (OTP), esquema que utilitza la criptografia simètrica en combinació amb un mòdul de maquinari de seguretat. Amés, aquesta solució ofereix mobilitat convenient per als usuaris que volen bancària en línia en qualsevol moment i en qualsevol lloc, no només des dels seus propis equips de confiança.La información financiera es extremadamente sensible. Por lo tanto, la banca electrónica debe proporcionar un sistema robusto para autenticar a sus clientes y hacerles acceder a sus datos de forma remota. Por otra parte, dicho sistema debe ser usable, accesible, y portátil. Se propone una respuesta al desafío basado en una contraseña única (OTP), esquema que utiliza la criptografía simétrica en combinación con un módulo hardware de seguridad hardware. Además, esta solución ofrece una movilidad conveniente para los usuarios que quieren la entidad bancaria en línea en cualquier momento y en cualquier lugar, no sólo des de sus propios equipos de confianza

A cooperative cellular and broadcast conditional access system for Pay-TV systems

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2009 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.The lack of interoperability between Pay-TV service providers and a horizontally integrated business transaction model have compromised the competition in the Pay-TV market. In addition, the lack of interactivity with customers has resulted in high churn rate and improper security measures have contributed into considerable business loss. These issues are the main cause of high operational costs and subscription fees in the Pay-TV systems. As a result, this paper presents the Mobile Conditional Access System (MICAS) as an end-to-end access control solution for Pay-TV systems. It incorporates the mobile and broadcasting systems and provides a platform whereby service providers can effectively interact with their customers, personalize their services and adopt appropriate security measurements. This would result in the decrease of operating expenses and increase of customers' satisfaction in the system. The paper provides an overview of state-of-the-art conditional access solutions followed by detailed description of design, reference model implementation and analysis of possible MICAS security architectures.Strategy & Technology (S&T) Lt