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Deniable Authentication and Key Exchange.

Mario Di Raimondo, Rosario Gennaro, Hugo Krawczyk

Published Jan 1, 2006• 2 citations
OpenAlex

Abstract

Abstract. We extend the definitional work of Dwork, Naor and Sahai from deniable authentication to deniable key-exchange protocols. We then use these definitions to prove the deniability features of SKEME and SIGMA, two natural and efficient protocols which serve as basis for the Internet Key Exchange (IKE) protocol. The two protocols require distinct approaches to their deniability analysis, hence highlighting important definitional issues as well as necessitating different tools in the analysis. SKEME is an encryption-based protocol for which we prove full deniability based on the plaintext awareness of the underlying encryption scheme. Interestingly SKEME’s deniability is possibly the first “natural ” application which essentially requires plaintext awareness (until now this notion has been mainly used as a tool for proving chosen-ciphertext security); in particular this use of plaintext awareness is not tied to the random oracle model. SIGMA, on the other hand, uses non-repudiable signatures for authentication and hence cannot be proven to be fully deniable. Yet we are able to prove a weaker, but meaningful, “partial deniability ” property: a party may not be able to deny that it was “alive ” at some point in time but can fully deny the contents of its communications and the identity of its interlocutors. We remark that the deniability of SKEME and SIGMA holds in a concurrent setting and does not essentially rely on the random oracle model.

Related papers

Deniable authentication and key exchange

Mario Di Raimondo, Rosario Gennaro, Hugo Krawczyk

We extend the definitional work of Dwork,Naor and Sahai from deniable authentication to deniable key-exchange protocols. We then use these definitions to prove the deniability features of SKEME and SIGMA, two natural and efficient protocols which serve as basis for the Internet Key Exchange (IKE)protocol.SKEME is an encryption-based protocol for which we prove full deniability based on the plaintext awareness of the underlying encryption scheme. Interestingly SKEME's deniability is possibly the first "natural" application which essentially requires plaintext awareness (until now this notion has been mainly used as a tool for proving chosen-ciphertext security).SIGMA, on the other hand,uses non-repudiable signatures for authentication and hence cannot be proven to be fully deniable. Yet we are able to prove a weaker, but meaningful, "partial deniability" property: a party may not be able to deny that it was "alive" at some point in time but can fully deny the contents of its communications and the identity of its interlocutors.We remark that the deniability of SKEME and SIGMA holds in a concurrent setting and does not essentially rely on the random oracle model.

ACM SIGSAC Conference on Computer and Communications Security (CCS)•Oct 30, 2006•128 citations

Deniable Internet Key-Exchange.

Andrew Chi-Chih Yao, Frances Yao, Yunlei Zhao +1 more

In this work, we develop a family of protocols for deniable Internet Key-Exchange (IKE) with the following properties: • Highly practical efficiency, and conceptual simplicity and clarity. • Forward and concurrent (non-malleable) deniability against adversaries with arbitrary auxiliary inputs, and better privacy protection of players ’ roles. • Provable security in the Canetti-Krawczyk post-specified-peer model, and maintenance of essential security properties not captured by the Canetti-Krawczyk security model. • Compatibility with the widely deployed and standardized SIGMA (i.e., the basis of IKEv2) and (H)MQV protocols, when parties possess DL public-keys. Our protocols could potentially serve, in part, as either the underlying basis or a useful alternative for the next generation of IKE (i.e., IKEv3) of IPsec (in particular, when deniability is desired). In view of the wide deployment and use of IKE and increasing awareness of privacy protection (especially for E-commerce over Internet), this work is naturally of practical interest.

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Deniable Authentication on the Internet.

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Abstract. Deniable authentication is a technique that allows one party to send messages to another while the latter can not prove to a third party the fact of communication. In this paper, we first formalize a natural notion of deniable security and naturally extend the basic authenticator theorem by Bellare et al. [2] to the setting of deniable authentication. Of independent interest, this extension is achieved by defining a deniable MT-authenticator via a game. This game is essentially borrowed from the notion of universal composition [8] although we do not assume any result or background about it. Then we construct two deniable MT-authenticators: uncontrollable random oracle based and the PKI based, both of which are just 3-round protocols. The second construction assumes the receiver owns a secret key. Such a setup assumption is very popular in the real world. (Without this assumption), all the previous protocols do not have a widely satisfiable performance when applied in the Internet-like environment. Finally, as our application, we obtain key exchange protocols that is deniably secure in the real world. 1

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Authenticated Deniable Internet KeyExchange

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We propose two public-key schemes to achieve deniable authentication for the Internet Key Exchange (IKE). Authentication in security had is the essential factor in the key establishment over Internet. The Deniable Internet key exchange protocol gives more value to the IKE standard. Our schemes can in some situations be more efficient than existing IKE protocols as well as having stronger deniability properties. Key-exchange, in particular Diffie–Hellman key exchange (DHKE), is among the core cryptographic mechanisms for ensuring network security. For key-exchange over the Internet, both security and privacy are desired. In this paper, we develop a family of privacy-preserving authenticated DHKE protocols named deniable Internet key-exchange (DIKE), both in the traditional PKI setting and in the identity-based setting. The newly developed DIKE protocols are of conceptual clarity and practical (online) efficiency. They provide useful privacy protection to both protocol participants, and add novelty and new value to the IKE standard.

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Timed Encryption and Its Application.

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Abstract. In this paper, we propose a new notion of timed encryption, in which the encryption is secure within time t while it is totally insecure after some time T> t. We are interested in the case where t and T are both polynomial. We propose a concrete construction that is provably secure in the random oracle model. We show that it can be generically (although inefficient) constructed from a timed commitment of Boneh and Naor (CRYPTO’00). Finally, we apply this primitive to construct a deniable secure key exchange protocol, where the deniability and secrecy both hold adaptively and the adversary can conduct session state reveal attacks and eavesdropping attacks in the non-eraser model. Our protocol is the first to achieve each of the following properties: adaptive deniability admitting eavesdropping attacks and deniability admitting session state reveal attacks in the non-eraser model. Our protocol is constructed using a timing restriction (inherited from the timed encryption). However, the requirement is rather weak. It essentially asks a user to respond to a ciphertext as soon as possible and hence does not artificially cause any delay. Our usage of timed encryption for the deniability is to use the forceful decryption to obtain the plaintext and hence does not use any random oracle assumption (even if the secrecy proof needs this).

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New approaches for deniable authentication

Mario Di Raimondo, Rosario Gennaro

Deniable Authentication protocols allow a Sender to authenticate a message for a Receiver, in a way that the Receiver cannot convince a third party that such authentication (or any authentication) ever took place.We present two new approaches to the problem of deniable authentication. The novelty of our schemes is that they do not require the use of CCA-secure encryption (all previous known solutions did), thus showing a different generic approach to the problem of deniable authentication. This new approach is practically relevant as it leads to more efficient protocols and security reductions.In the process we point out a subtle definitional issue for deniability. In particular we propose the notion of forward deniability, which requires that the authentications remain deniable even if the Sender wants to later prove that she authenticated a message. We show that forward deniability is not implied by the original notion of deniability, by showing some deniable protocols which are not forward deniable. Our new proposals are forward deniable.

ACM SIGSAC Conference on Computer and Communications Security (CCS)•Nov 7, 2005•69 citations
Abstract. We extend the definitional work of Dwork, Naor and Sahai from deniable authentication to deniable key-exchange protocols. We then use these definitions to prove the deniability features of SKEME and SIGMA, two natural and efficient protocols which serve as basis for the Internet Key Exchange (IKE) protocol. The two protocols require distinct approaches to their deniability analysis, hence highlighting important definitional issues as well as necessitating different tools in the analysis. SKEME is an encryption-based protocol for which we prove full deniability based on the plaintext awareness of the underlying encryption scheme. Interestingly SKEME’s deniability is possibly the first “natural ” application which essentially requires plaintext awareness (until now this notion has been mainly used as a tool for proving chosen-ciphertext security); in particular this use of plaintext awareness is not tied to the random oracle model. SIGMA, on the other hand, uses non-repudiable signatures for authentication and hence cannot be proven to be fully deniable. Yet we are able to prove a weaker, but meaningful, “partial deniability ” property: a party may not be able to deny that it was “alive ” at some point in time but can fully deny the contents of its communications and the identity of its interlocutors. We remark that the deniability of SKEME and SIGMA holds in a concurrent setting and does not essentially rely on the random oracle model.
We extend the definitional work of Dwork,Naor and Sahai from deniable authentication to deniable key-exchange protocols. We then use these definitions to prove the deniability features of SKEME and SIGMA, two natural and efficient protocols which serve as basis for the Internet Key Exchange (IKE)protocol.SKEME is an encryption-based protocol for which we prove full deniability based on the plaintext awareness of the underlying encryption scheme. Interestingly SKEME's deniability is possibly the first "natural" application which essentially requires plaintext awareness (until now this notion has been mainly used as a tool for proving chosen-ciphertext security).SIGMA, on the other hand,uses non-repudiable signatures for authentication and hence cannot be proven to be fully deniable. Yet we are able to prove a weaker, but meaningful, "partial deniability" property: a party may not be able to deny that it was "alive" at some point in time but can fully deny the contents of its communications and the identity of its interlocutors.We remark that the deniability of SKEME and SIGMA holds in a concurrent setting and does not essentially rely on the random oracle model.
In this work, we develop a family of protocols for deniable Internet Key-Exchange (IKE) with the following properties: • Highly practical efficiency, and conceptual simplicity and clarity. • Forward and concurrent (non-malleable) deniability against adversaries with arbitrary auxiliary inputs, and better privacy protection of players ’ roles. • Provable security in the Canetti-Krawczyk post-specified-peer model, and maintenance of essential security properties not captured by the Canetti-Krawczyk security model. • Compatibility with the widely deployed and standardized SIGMA (i.e., the basis of IKEv2) and (H)MQV protocols, when parties possess DL public-keys. Our protocols could potentially serve, in part, as either the underlying basis or a useful alternative for the next generation of IKE (i.e., IKEv3) of IPsec (in particular, when deniability is desired). In view of the wide deployment and use of IKE and increasing awareness of privacy protection (especially for E-commerce over Internet), this work is naturally of practical interest.
Abstract. Deniable authentication is a technique that allows one party to send messages to another while the latter can not prove to a third party the fact of communication. In this paper, we first formalize a natural notion of deniable security and naturally extend the basic authenticator theorem by Bellare et al. [2] to the setting of deniable authentication. Of independent interest, this extension is achieved by defining a deniable MT-authenticator via a game. This game is essentially borrowed from the notion of universal composition [8] although we do not assume any result or background about it. Then we construct two deniable MT-authenticators: uncontrollable random oracle based and the PKI based, both of which are just 3-round protocols. The second construction assumes the receiver owns a secret key. Such a setup assumption is very popular in the real world. (Without this assumption), all the previous protocols do not have a widely satisfiable performance when applied in the Internet-like environment. Finally, as our application, we obtain key exchange protocols that is deniably secure in the real world. 1
We propose two public-key schemes to achieve deniable authentication for the Internet Key Exchange (IKE). Authentication in security had is the essential factor in the key establishment over Internet. The Deniable Internet key exchange protocol gives more value to the IKE standard. Our schemes can in some situations be more efficient than existing IKE protocols as well as having stronger deniability properties. Key-exchange, in particular Diffie–Hellman key exchange (DHKE), is among the core cryptographic mechanisms for ensuring network security. For key-exchange over the Internet, both security and privacy are desired. In this paper, we develop a family of privacy-preserving authenticated DHKE protocols named deniable Internet key-exchange (DIKE), both in the traditional PKI setting and in the identity-based setting. The newly developed DIKE protocols are of conceptual clarity and practical (online) efficiency. They provide useful privacy protection to both protocol participants, and add novelty and new value to the IKE standard.
Abstract. In this paper, we propose a new notion of timed encryption, in which the encryption is secure within time t while it is totally insecure after some time T> t. We are interested in the case where t and T are both polynomial. We propose a concrete construction that is provably secure in the random oracle model. We show that it can be generically (although inefficient) constructed from a timed commitment of Boneh and Naor (CRYPTO’00). Finally, we apply this primitive to construct a deniable secure key exchange protocol, where the deniability and secrecy both hold adaptively and the adversary can conduct session state reveal attacks and eavesdropping attacks in the non-eraser model. Our protocol is the first to achieve each of the following properties: adaptive deniability admitting eavesdropping attacks and deniability admitting session state reveal attacks in the non-eraser model. Our protocol is constructed using a timing restriction (inherited from the timed encryption). However, the requirement is rather weak. It essentially asks a user to respond to a ciphertext as soon as possible and hence does not artificially cause any delay. Our usage of timed encryption for the deniability is to use the forceful decryption to obtain the plaintext and hence does not use any random oracle assumption (even if the secrecy proof needs this).
Deniable Authentication protocols allow a Sender to authenticate a message for a Receiver, in a way that the Receiver cannot convince a third party that such authentication (or any authentication) ever took place.We present two new approaches to the problem of deniable authentication. The novelty of our schemes is that they do not require the use of CCA-secure encryption (all previous known solutions did), thus showing a different generic approach to the problem of deniable authentication. This new approach is practically relevant as it leads to more efficient protocols and security reductions.In the process we point out a subtle definitional issue for deniability. In particular we propose the notion of forward deniability, which requires that the authentications remain deniable even if the Sender wants to later prove that she authenticated a message. We show that forward deniability is not implied by the original notion of deniability, by showing some deniable protocols which are not forward deniable. Our new proposals are forward deniable.