An Overview of Identity Based Encryption

An Overview of Identity Based Encryption – A White Paper by VertodaCopyright © Sykoinia Limited 20091An Overview of Identity Based Encryption – A White Paper by VertodaCopyright © Sykoinia Limited 20092An Overview of Identity Based Encryption – A White Paper by VertodaPlease Read before reading this White PaperThis white paper is not distributed under a GPL license. Use of this white paper is subject to the following terms:  This white paper is copyrighted by Sykoinia Limited. Copyright © Sykoinia Limited 2009. All Rights Reserved. You may create a printed copy of this white paper solely for your own personal use.  Conversion to other formats is allowed as long as the actual content is not altered or edited in any way.  You shall not publish or distribute this white paper in any form or on any media, except if you distribute the documentation in a manner similar to how Sykoinia Limiteddisseminates it (that is, electronically for download on a Web site with the software) or on a CD-ROM or similar medium, provided however that the white paper is disseminated together with the software on the same medium. Any other use, such as any dissemination of printed copies or use of this white paper, in whole or in part, in another publication, requires the prior written consent from an authorised representative of Sykoinia Limited. Sykoinia Limited reserves any and all rights to this white paper not expressly granted above. For more information on the terms of this license or if you are interested in doing a translation, please contact us at info@vertoda.com.If you find a typographical error in this white paper or if you have thought of a way to make this white paper better please contact us at info@vertoda.com.Please note that this white paper is for informational purposes. Sykoinia Limited accepts no responsibility for any loss due to the use of this white paper.If you have any comments please email us at info@vertoda.com with your feedback. Copyright © Sykoinia Limited 20093An Overview of Identity Based Encryption – A White Paper by VertodaAbstractThis white paper reviews Identity Based Encryption (IBE) and Identity Based Signatures (IBS) and explores how the schemes work. A review of current research and literature in the area is carried out and practical implementations of the schemes are considered. We then consider open issues and possible future work in the area. Copyright © Sykoinia Limited 20094An Overview of Identity Based Encryption – A White Paper by VertodaTable of ContentsTable of Contents....................................................................................................................................5Table of Figures.......................................................................................................................................6Glossary...................................................................................................................................................71. Introduction ........................................................................................................................................82. Common Key Management Systems ..................................................................................................93. Identity Based Encryption.................................................................................................................134. Literature & Academic Research.......................................................................................................165. Applications......................................................................................................................................196. Implementations of IBE.....................................................................................................................207. Open Problems & Future Work.........................................................................................................219. Digital Signatures & Identity Based Signature Schemes...................................................................2211. Conclusion.......................................................................................................................................26Copyright © Sykoinia Limited 20095An Overview of Identity Based Encryption – A White Paper by VertodaTable of FiguresFigure 1: Symmetric Key Management ..................................................................................................................11Figure 2: PKI Key Management System................................................................................................................12Figure 3: Identity Based Encryption.......................................................................................................................14Figure 4: Sending an Email using Identity Based Encryption ............................................................................ 15Figure 5: Hierarchy of Private Key Generators ....................................................................................................18Figure 6: A Typical Digital Signature Scheme.......................................................................................................22Figure 7: Creating a Digital Signature.....................................................................................................................23Figure 8: Verifying a Digital Signature....................................................................................................................24Copyright © Sykoinia Limited 20096An Overview of Identity Based Encryption – A White Paper by VertodaGlossaryA-IBEAccountable Authority Identity Based EncryptionBDHBilinear Diffie-Hellmann AssumptionCACertifying AuthorityCBECertificate Based EncryptionECCElliptic Curve CryptographyGIBEGeneralized Identity Based and Broadcast Encryption SchemeHIBEHierarchical ID-Based EncryptionIBEIdentity Based EncryptionIBSIdentity Based Signature SchemeJCAJava Cryptography ArchitectureJCEJava Cryptography ExtensionsMACMessage Authentication CodePEKSPublic Key Encryption with Keyword SearchPKGPrivate Key GeneratorPKIPublic Key InfrastructureWSNWireless Sensor NetworkCopyright © Sykoinia Limited 20097An Overview of Identity Based Encryption – A White Paper by Vertoda1. IntroductionIdentity Based Encryption (IBE) is a public cryptographic scheme where any piece of text can act as a valid public key. This is a powerful concept as it means that email addresses, dates or a combination of both can act as public keys. The concept of IBE was first proposed by Shamir [1]. However, despite many proposals no satisfactory implementation of IBE was formulated until 2001 by Boneh and Franklin [2].This whitepaper will explore how IBE works and will review current literature on the area. Current and potential applications of IBE will be investigated. Implementations of IBE will be assessed and. We will also propose future work in the area. We will then consider Digital Signature Schemes and the Identity Based Signature (IBS) Scheme in particular. Firstly though, we will assess the most common key management systems.Copyright © Sykoinia Limited 20098An Overview of Identity Based Encryption – A White Paper by Vertoda2. Common Key Management SystemsThe Voltage Corporation’s white paper on IBE [3] outlines the requirements for key management in an enterprise environment. These are:1. Delivery of Encryption Keys for internal recipients, customers and partners.2. Authenticate users and deliver decryption keys to users and groups specified by the data sender.3. Jointly manage keys with partners where each partner only needs to manage keys for its own users.4. Deliver keys to trusted infrastructure components e.g. technical and business processes such as content scanning, auditing, or anti-virus.5. Recover Keys e.g. in scenarios where a user leaves the organisation or machines lose disk storage.6. Scale for Growth so that large transaction volumes can be managed and load-balanced and geographic deployments are possible.This whitepaper [3] also argues that these requirements are not met by the most common key management systems – symmetric key management and public key infrastructure (PKI) key management.illustrates the operation of a Symmetric Key Management system. In essence, the sender tells the key manager who is receiving the data to be encrypted and an encryption key is set. The receiver of the encrypted data then authenticates that the data is coming from a valid sender via the key manager who in turn sends the decryption key so as to enable the data to be decrypted. The cardinal point to note here is that the same key is used to encrypt and decrypt the data. This means that Symmetric Key management systems are fast from a performance perspective. However, in many cases, Symmetric Key Management systems have high storage costs as they require a database to store the generated keys. Furthermore, the key manager must always be available as it plays a role in every encryption and decryption operation.Figure 2 illustrates the Public Key Infrastructure (PKI) Key Management system. The PKI system uses what are termed public key or asymmetric algorithms where the key used to decrypt data is different from the key used to encrypt the data. In this system, a public and private key are created simultaneously by a certifying authority (CA). The private key is given only to the requesting party (in Figure 2, the receiver) and the public key is made available as part of a digital certificate in a directory that all parties can access. The private key is never shared and cannot be accessed via the Internet. Thus, as per Figure 2 the sender accesses the public key from the Copyright © Sykoinia Limited 20099An Overview of Identity Based Encryption – A White Paper by Vertodacentral directory and encrypts the data using this key. The receiver then authenticates that the sender is a valid one from the CA and then decrypts the data with their private key.One advantage PKI systems have over their Symmetric Key counterparts is that there is no requirement for a key server to be contacted for each message sent. However, key recovery is difficult as the recipient generates the private keys him/herself. In addition, a sender must locate a public key for every recipient and authenticate its validity – this is not always possible as the directory may not be able to supply public keys for all recipients.Limitations with both key management systems are apparent when we consider the issue of mobility. In the case of Symmetric Key Management systems, a very large key management database would be required when mobile commerce transactions are factored in. We would also need to consider the fact that the transactions would exponentially increase the number of operations the key server needs to handle. In the case of PKI Key Management systems the complexity of its operation would seem to make its practical implementation for Mobile Commerce systems difficult especially given that the issue of key recovery would be exacerbated with mobile recipients.Copyright © Sykoinia Limited 200910