The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Bogdan Warinschi - One of the best experts on this subject based on the ideXlab platform.
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Security of the Enhanced TCG Privacy-CA Solution
2014Co-Authors: Liqun Chen, Ming-feng Lee, Bogdan WarinschiAbstract:Abstract. The privacy-CA solution (PCAS) designed by the trusted computing group (TCG) was specified in TCG trusted Platform Module (TPM) Specification Version 1.2 in 2003 and allows a TPM to obtain from a certification authority (CA) certificates on short term keys. The PCAS protocol is a lighter alternative to the Direct Anonymous Attestation (DAA) scheme for anonymous platform authentication. The first rigorous analysis of PCAS was recently performed by Chen and Warinschi who focus on an unforgeability property (a TPM cannot obtain a certificate without the CA knowing its identity). The analysis in that paper holds only when no TPM is corrupt as, otherwise, an attack can be easily mounted. The authors also propose a stronger protocol (which we refer to as the enhanced PCAS or ePCAS) intended to withstand attacks of corrupt TPMs, but the protocol had never been formally analyzed. The contribution of this paper is two-fold. We formalize three security properties desired from the ePCAS protocol. Unforgeability refines the earlier model for the case where TPMs may be corrupted. Deniability is the property that a CA cannot prove to a third party that he engaged in a run of the protocol with a certain TPM. Finally, anonymity is the property that third parties cannot tell the identity of TPMs based on the certificates that the TPM uses. The second contribution are proofs that the ePCAS protocol does indeed satisfy the security requirements that we formalize in this paper
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Anonymous attestation with user-controlled linkability
International Journal of Information Security, 2013Co-Authors: David Bernhard, Essam Ghadafi, Georg Fuchsbauer, Nigel P. Smart, Bogdan WarinschiAbstract:This paper is motivated by the observation that existing security models for direct anonymous attestation (DAA) have problems to the extent that insecure protocols may be deemed secure when analysed under these models. This is particularly disturbing as DAA is one of the few complex cryptographic protocols resulting from recent theoretical advances actually deployed in real life. Moreover, standardization bodies are currently looking into designing the next generation of such protocols. Our first contribution is to identify issues in existing models for DAA and explain how these errors allow for proving security of insecure protocols. These issues are exhibited in all deployed and proposed DAA protocols (although they can often be easily fixed). Our second contribution is a new security model for a class of “pre-DAA scheme”, that is, DAA schemes where the computation on the user side takes place entirely on the trusted platform. Our model captures more accurately than any previous model the security properties demanded from DAA by the trusted computing group (TCG), the group that maintains the DAA standard. Extending the model from pre-DAA to full DAA is only a matter of refining the trust models on the parties involved. Finally, we present a generic construction of a DAA protocol from new building blocks tailored for anonymous attestation. Some of them are new variations on established ideas and may be of independent interest. We give instantiations for these building blocks that yield a DAA scheme more efficient than the one currently deployed, and as efficient as the one about to be standardized by the TCG which has no valid security proof.
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Anonymous attestation with user-controlled linkability
International Journal of Information Security, 2013Co-Authors: David Bernhard, Essam Ghadafi, Georg Fuchsbauer, Nigel P. Smart, Bogdan WarinschiAbstract:This paper is motivated by the observation that existing security models for direct anonymous attestation (DAA) have problems to the extent that insecure protocols may be deemed secure when analysed under these models. This is particularly disturbing as DAA is one of the few complex cryptographic protocols resulting from recent theoretical advances actually deployed in real life. Moreover, standardization bodies are currently looking into designing the next generation of such protocols. Our first contribution is to identify issues in existing models for DAA and explain how these errors allow for proving security of insecure protocols. These issues are exhibited in all deployed and proposed DAA protocols (although they can often be easily fixed). Our second contribution is a new security model for a class of “pre-DAA scheme”, that is, DAA schemes where the computation on the user side takes place entirely on the trusted platform. Our model captures more accurately than any previous model the security properties demanded from DAA by the trusted computing group (TCG), the group that maintains the DAA standard. Extending the model from pre-DAA to full DAA is only a matter of refining the trust models on the parties involved. Finally, we present a generic construction of a DAA protocol from new building blocks tailored for anonymous attestation. Some of them are new variations on established ideas and may be of independent interest. We give instantiations for these building blocks that yield a DAA scheme more efficient than the one currently deployed, and as efficient as the one about to be standardized by the TCG which has no valid security proof.
Jan Camenisch - One of the best experts on this subject based on the ideXlab platform.
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Direct anonymous attestation
2016Co-Authors: Jan Camenisch, Liqun Chen, Available From Liqun Chen, Ernie BrickellAbstract:direct anonymous attestation, DAA, trusted computing, group signatures This paper describes the direct anonymous attestation scheme (DAA). This scheme was adopted by the trusted computing group as the method for remote authentication of a hardware module, called trusted platform module (TPM), while preserving the privacy of the user of the platform that contains the module. Direct anonymous attestation can be seen as a group signature without the feature that a signature can be opened, i.e., the anonymity is not revocable. Moreover, DAA allows for pseudonyms, i.e., for each signature a user (in agreement with the recipient of the signature) can decide whether or not the signature should be linkable to another signature. DAA furthermore allows for detection of "known " keys: if the DAA secret keys are extracted from a TPM and published, a verifier can detect that a signature was produced using these secret keys. The scheme is provably secure in the random oracle model under the strong RSA and the decisional Diffie-Hellman assumption
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protecting anonymous credentials with the trusted computing group s tpm v1 2
Information Security Conference, 2006Co-Authors: Jan CamenischAbstract:Digital credentials and certificates can easily be shared and copied. For instance, if a user possesses a credential that allows her to access some service, she can easily share it with her friends and thereby let them use the service as well. While with non-anonymous credentials, this sharing can to some extend be detected by the fact that some credentials get used too often, such detection is not possible with anonymous credentials. Furthermore, the honest user is also at risk of identity theft: malicious software such as viruses and worms or phishing attacks can without too much difficulty steal her credentials.
David Bernhard - One of the best experts on this subject based on the ideXlab platform.
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Anonymous attestation with user-controlled linkability
International Journal of Information Security, 2013Co-Authors: David Bernhard, Essam Ghadafi, Georg Fuchsbauer, Nigel P. Smart, Bogdan WarinschiAbstract:This paper is motivated by the observation that existing security models for direct anonymous attestation (DAA) have problems to the extent that insecure protocols may be deemed secure when analysed under these models. This is particularly disturbing as DAA is one of the few complex cryptographic protocols resulting from recent theoretical advances actually deployed in real life. Moreover, standardization bodies are currently looking into designing the next generation of such protocols. Our first contribution is to identify issues in existing models for DAA and explain how these errors allow for proving security of insecure protocols. These issues are exhibited in all deployed and proposed DAA protocols (although they can often be easily fixed). Our second contribution is a new security model for a class of “pre-DAA scheme”, that is, DAA schemes where the computation on the user side takes place entirely on the trusted platform. Our model captures more accurately than any previous model the security properties demanded from DAA by the trusted computing group (TCG), the group that maintains the DAA standard. Extending the model from pre-DAA to full DAA is only a matter of refining the trust models on the parties involved. Finally, we present a generic construction of a DAA protocol from new building blocks tailored for anonymous attestation. Some of them are new variations on established ideas and may be of independent interest. We give instantiations for these building blocks that yield a DAA scheme more efficient than the one currently deployed, and as efficient as the one about to be standardized by the TCG which has no valid security proof.
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Anonymous attestation with user-controlled linkability
International Journal of Information Security, 2013Co-Authors: David Bernhard, Essam Ghadafi, Georg Fuchsbauer, Nigel P. Smart, Bogdan WarinschiAbstract:This paper is motivated by the observation that existing security models for direct anonymous attestation (DAA) have problems to the extent that insecure protocols may be deemed secure when analysed under these models. This is particularly disturbing as DAA is one of the few complex cryptographic protocols resulting from recent theoretical advances actually deployed in real life. Moreover, standardization bodies are currently looking into designing the next generation of such protocols. Our first contribution is to identify issues in existing models for DAA and explain how these errors allow for proving security of insecure protocols. These issues are exhibited in all deployed and proposed DAA protocols (although they can often be easily fixed). Our second contribution is a new security model for a class of “pre-DAA scheme”, that is, DAA schemes where the computation on the user side takes place entirely on the trusted platform. Our model captures more accurately than any previous model the security properties demanded from DAA by the trusted computing group (TCG), the group that maintains the DAA standard. Extending the model from pre-DAA to full DAA is only a matter of refining the trust models on the parties involved. Finally, we present a generic construction of a DAA protocol from new building blocks tailored for anonymous attestation. Some of them are new variations on established ideas and may be of independent interest. We give instantiations for these building blocks that yield a DAA scheme more efficient than the one currently deployed, and as efficient as the one about to be standardized by the TCG which has no valid security proof.
Ravi Sandhu - One of the best experts on this subject based on the ideXlab platform.
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towards remote policy enforcement for runtime protection of mobile code using trusted computing
International Workshop on Security, 2006Co-Authors: Xinwe Zhang, Francesco Parisipresicce, Ravi SandhuAbstract:We present an approach to protect mobile code and agents at runtime using trusted computing (TC) technologies. For this purpose, a “mobile policy” is defined by the mobile code originator, and is enforced by the runtime environment in a remote host to control which users can run the mobile code and what kind of results a user can observe, depending on the security properties of the user. The separation of policy specification and implementation mechanism in existing mobile computing platform such as Java Runtime Environment (JRE) enables the implementation of our approach by leveraging current security technologies. The main difference between our approach and existing runtime security models is that the policies enforced in our model are intended to protect the resources of the mobile applications instead of the local system resources. This requires the remote runtime environment to be trusted by the application originator to authenticate the remote user and enforce the policy. Emerging TC technologies such as specified by the trusted computing group (TCG) provide assurance of the runtime environment of a remote host.
Nigel P. Smart - One of the best experts on this subject based on the ideXlab platform.
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Anonymous attestation with user-controlled linkability
International Journal of Information Security, 2013Co-Authors: David Bernhard, Essam Ghadafi, Georg Fuchsbauer, Nigel P. Smart, Bogdan WarinschiAbstract:This paper is motivated by the observation that existing security models for direct anonymous attestation (DAA) have problems to the extent that insecure protocols may be deemed secure when analysed under these models. This is particularly disturbing as DAA is one of the few complex cryptographic protocols resulting from recent theoretical advances actually deployed in real life. Moreover, standardization bodies are currently looking into designing the next generation of such protocols. Our first contribution is to identify issues in existing models for DAA and explain how these errors allow for proving security of insecure protocols. These issues are exhibited in all deployed and proposed DAA protocols (although they can often be easily fixed). Our second contribution is a new security model for a class of “pre-DAA scheme”, that is, DAA schemes where the computation on the user side takes place entirely on the trusted platform. Our model captures more accurately than any previous model the security properties demanded from DAA by the trusted computing group (TCG), the group that maintains the DAA standard. Extending the model from pre-DAA to full DAA is only a matter of refining the trust models on the parties involved. Finally, we present a generic construction of a DAA protocol from new building blocks tailored for anonymous attestation. Some of them are new variations on established ideas and may be of independent interest. We give instantiations for these building blocks that yield a DAA scheme more efficient than the one currently deployed, and as efficient as the one about to be standardized by the TCG which has no valid security proof.
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Anonymous attestation with user-controlled linkability
International Journal of Information Security, 2013Co-Authors: David Bernhard, Essam Ghadafi, Georg Fuchsbauer, Nigel P. Smart, Bogdan WarinschiAbstract:This paper is motivated by the observation that existing security models for direct anonymous attestation (DAA) have problems to the extent that insecure protocols may be deemed secure when analysed under these models. This is particularly disturbing as DAA is one of the few complex cryptographic protocols resulting from recent theoretical advances actually deployed in real life. Moreover, standardization bodies are currently looking into designing the next generation of such protocols. Our first contribution is to identify issues in existing models for DAA and explain how these errors allow for proving security of insecure protocols. These issues are exhibited in all deployed and proposed DAA protocols (although they can often be easily fixed). Our second contribution is a new security model for a class of “pre-DAA scheme”, that is, DAA schemes where the computation on the user side takes place entirely on the trusted platform. Our model captures more accurately than any previous model the security properties demanded from DAA by the trusted computing group (TCG), the group that maintains the DAA standard. Extending the model from pre-DAA to full DAA is only a matter of refining the trust models on the parties involved. Finally, we present a generic construction of a DAA protocol from new building blocks tailored for anonymous attestation. Some of them are new variations on established ideas and may be of independent interest. We give instantiations for these building blocks that yield a DAA scheme more efficient than the one currently deployed, and as efficient as the one about to be standardized by the TCG which has no valid security proof.
