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Universally composable security: A new paradigm for cryptographic protocols
, 2013
"... We present a general framework for representing cryptographic protocols and analyzing their security. The framework allows specifying the security requirements of practically any cryptographic task in a unified and systematic way. Furthermore, in this framework the security of protocols is preserved ..."
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Cited by 842 (43 self)
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We present a general framework for representing cryptographic protocols and analyzing their security. The framework allows specifying the security requirements of practically any cryptographic task in a unified and systematic way. Furthermore, in this framework the security of protocols is preserved under a general protocol composition operation, called universal composition. The proposed framework with its securitypreserving composition operation allows for modular design and analysis of complex cryptographic protocols from relatively simple building blocks. Moreover, within this framework, protocols are guaranteed to maintain their security in any context, even in the presence of an unbounded number of arbitrary protocol instances that run concurrently in an adversarially controlled manner. This is a useful guarantee, that allows arguing about the security of cryptographic protocols in complex and unpredictable environments such as modern communication networks.
A Unified Framework for the Analysis of SideChannel Key Recovery Attacks
, 2009
"... The fair evaluation and comparison of sidechannel attacks and countermeasures has been a long standing open question, limiting further developments in the field. Motivated by this challenge, this work makes a step in this direction and proposes a framework for the analysis of cryptographic implem ..."
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Cited by 138 (10 self)
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The fair evaluation and comparison of sidechannel attacks and countermeasures has been a long standing open question, limiting further developments in the field. Motivated by this challenge, this work makes a step in this direction and proposes a framework for the analysis of cryptographic implementations that includes a theoretical model and an application methodology. The model is based on commonly accepted hypotheses about sidechannels that computations give rise to. It allows quantifying the effect of practically relevant leakage functions with a combination of information theoretic and security metrics, measuring the quality of an implementation and the strength of an adversary, respectively. From a theoretical point of view, we demonstrate formal connections between these metrics and discuss their intuitive meaning. From a practical point of view, the model implies a unified methodology for the analysis of sidechannel key recovery attacks. The proposed solution allows getting rid of most of the subjective parameters that were limiting previous specialized and often ad hoc approaches in the evaluation of physically observable devices. It typically determines the extent to which basic (but practically essential) questions such as “How to compare two implementations?” or “How to compare two sidechannel adversaries?” can be answered in a sound fashion.
Private Circuits: Securing Hardware against Probing Attacks
 In Proceedings of CRYPTO 2003
, 2003
"... Abstract. Can you guarantee secrecy even if an adversary can eavesdrop on your brain? We consider the problem of protecting privacy in circuits, when faced with an adversary that can access a bounded number of wires in the circuit. This question is motivated by side channel attacks, which allow an a ..."
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Cited by 130 (7 self)
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Abstract. Can you guarantee secrecy even if an adversary can eavesdrop on your brain? We consider the problem of protecting privacy in circuits, when faced with an adversary that can access a bounded number of wires in the circuit. This question is motivated by side channel attacks, which allow an adversary to gain partial access to the inner workings of hardware. Recent work has shown that side channel attacks pose a serious threat to cryptosystems implemented in embedded devices. In this paper, we develop theoretical foundations for security against side channels. In particular, we propose several efficient techniques for building private circuits resisting this type of attacks. We initiate a systematic study of the complexity of such private circuits, and in contrast to most prior work in this area provide a formal threat model and give proofs of security for our constructions.
PublicKey Cryptosystems Resilient to Key Leakage
"... Most of the work in the analysis of cryptographic schemes is concentrated in abstract adversarial models that do not capture sidechannel attacks. Such attacks exploit various forms of unintended information leakage, which is inherent to almost all physical implementations. Inspired by recent sidec ..."
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Cited by 89 (6 self)
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Most of the work in the analysis of cryptographic schemes is concentrated in abstract adversarial models that do not capture sidechannel attacks. Such attacks exploit various forms of unintended information leakage, which is inherent to almost all physical implementations. Inspired by recent sidechannel attacks, especially the “cold boot attacks ” of Halderman et al. (USENIX Security ’08), Akavia, Goldwasser and Vaikuntanathan (TCC ’09) formalized a realistic framework for modeling the security of encryption schemes against a wide class of sidechannel attacks in which adversarially chosen functions of the secret key are leaked. In the setting of publickey encryption, Akavia et al. showed that Regev’s latticebased scheme (STOC ’05) is resilient to any leakage of
Appendonly signatures
 in International Colloquium on Automata, Languages and Programming
, 2005
"... Abstract. The strongest standard security notion for digital signature schemes is unforgeability under chosen message attacks. In practice, however, this notion can be insufficient due to “sidechannel attacks ” which exploit leakage of information about the secret internal state. In this work we pu ..."
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Cited by 53 (10 self)
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Abstract. The strongest standard security notion for digital signature schemes is unforgeability under chosen message attacks. In practice, however, this notion can be insufficient due to “sidechannel attacks ” which exploit leakage of information about the secret internal state. In this work we put forward the notion of “leakageresilient signatures, ” which strengthens the standard security notion by giving the adversary the additional power to learn a bounded amount of arbitrary information about the secret state that was accessed during every signature generation. This notion naturally implies security against all sidechannel attacks as long as the amount of information leaked on each invocation is bounded and “only computation leaks information.” The main result of this paper is a construction which gives a (treebased, stateful) leakageresilient signature scheme based on any 3time signature scheme. The amount of information that our scheme can safely leak per signature generation is 1/3 of the information the underlying 3time signature scheme can leak in total. Signature schemes that remain secure even if a bounded total amount of information is leaked were recently constructed, hence instantiating our construction with these schemes gives the first constructions of provably secure leakageresilient signature schemes. The above construction assumes that the signing algorithm can sample truly random bits, and thus an implementation would need some special hardware (randomness gates). Simply generating this randomness using a leakageresilient streamcipher will in general not work. Our second contribution is a sound general principle to replace uniform random bits in any leakageresilient construction with pseudorandom ones: run two leakageresilient streamciphers (with independent keys) in parallel and then apply a twosource extractor to their outputs. 1
Private Circuits II: Keeping Secrets In Tamperable Circuits
, 2006
"... Motivated by the problem of protecting cryptographic hardware, we continue the investigation of private circuits initiated in [16]. In this work, our aim is to construct circuits that should protect the secrecy of their internal state against an adversary who may modify the values of an unbounde ..."
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Cited by 41 (4 self)
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Motivated by the problem of protecting cryptographic hardware, we continue the investigation of private circuits initiated in [16]. In this work, our aim is to construct circuits that should protect the secrecy of their internal state against an adversary who may modify the values of an unbounded number of wires, anywhere in the circuit. In contrast, all previous works on protecting cryptographic hardware relied on an assumption that some portion of the circuit must remain completely free from tampering.
Signature schemes with bounded leakage resilience
 In ASIACRYPT
, 2009
"... A leakageresilient cryptosystem remains secure even if arbitrary, but bounded, information about the secret key (or possibly other internal state information) is leaked to an adversary. Denote the length of the secret key by n. We show a signature scheme tolerating (optimal) leakage of up to n − nǫ ..."
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Cited by 40 (1 self)
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A leakageresilient cryptosystem remains secure even if arbitrary, but bounded, information about the secret key (or possibly other internal state information) is leaked to an adversary. Denote the length of the secret key by n. We show a signature scheme tolerating (optimal) leakage of up to n − nǫ bits of information about the secret key, and a more efficient onetime signature scheme that tolerates leakage of ( 1 4 −ǫ) ·n bits of information about the signer’s entire state. The latter construction extends to give a leakageresilient ttime signature scheme. All these constructions are in the standard model under general assumptions. 1
The Program Counter Security Model: Automatic Detection and Removal of ControlFlow Side Channel Attacks
 In Cryptology ePrint Archive, Report 2005/368
, 2005
"... Abstract. We introduce new methods for detecting controlflow side channel attacks, transforming C source code to eliminate such attacks, and checking that the transformed code is free of controlflow side channels. We model controlflow side channels with a program counter transcript, in which the ..."
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Cited by 37 (0 self)
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Abstract. We introduce new methods for detecting controlflow side channel attacks, transforming C source code to eliminate such attacks, and checking that the transformed code is free of controlflow side channels. We model controlflow side channels with a program counter transcript, in which the value of the program counter at each step is leaked to an adversary. The program counter transcript model captures a class of side channel attacks that includes timing attacks and error disclosure attacks. Further, we propose a generic sourcetosource transformation that produces programs provably secure against controlflow side channel attacks. We implemented this transform for C together with a static checker that conservatively checks x86 assembly for violations of program counter security; our checker allows us to compile with optimizations while retaining assurance the resulting code is secure. We then measured our technique’s effect on the performance of binary modular exponentiation and realworld implementations in C of RC5 and IDEA: we found it has a performance overhead of at most 5 × and a stack space overhead of at most 2×. Our approach to side channel security is practical, generally applicable, and provably secure against an interesting class of side channel attacks. 1
On cryptography with auxiliary input
 DKL09] [DS05] [FGK+ 10] [FOR12] [GHV10
, 2009
"... We study the question of designing cryptographic schemes which are secure even if an arbitrary function f(sk) of the secret key is leaked, as long as the secret key sk is still (exponentially) hard to compute from this auxiliary input. This setting of auxiliary input is more general than the more tr ..."
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Cited by 33 (4 self)
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We study the question of designing cryptographic schemes which are secure even if an arbitrary function f(sk) of the secret key is leaked, as long as the secret key sk is still (exponentially) hard to compute from this auxiliary input. This setting of auxiliary input is more general than the more traditional setting, which assumes that some of information about the secret key sk may be leaked, but sk still has high minentropy left. In particular, we deal with situations where f(sk) informationtheoretically determines the entire secret key sk. As our main result, we construct CPA/CCA secure symmetric encryption schemes that remain secure with exponentially hardtoinvert auxiliary input. We give several applications of such schemes. • We construct an averagecase obfuscator for the class of point functions, which remains secure with exponentially hardtoinvert auxiliary input, and is reusable. • We construct a reusable and robust extractor that remains secure with exponentially hardtoinvert auxiliary input. Our results rely on a new cryptographic assumption, Learning SubspacewithNoise (LSN), which is related to the well known Learning ParitywithNoise (LPN) assumption.
Mutual Information Analysis ⋆ A Generic SideChannel Distinguisher
"... Abstract. We propose a generic informationtheoretic distinguisher for differential sidechannel analysis. Our model of sidechannel leakage is a refinement of the one given by Standaert et al. An embedded device containing a secret key is modeled as a black box with a leakage function whose output ..."
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Cited by 29 (5 self)
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Abstract. We propose a generic informationtheoretic distinguisher for differential sidechannel analysis. Our model of sidechannel leakage is a refinement of the one given by Standaert et al. An embedded device containing a secret key is modeled as a black box with a leakage function whose output is captured by an adversary through the noisy measurement of a physical observable. Although quite general, the model and the distinguisher are practical and allow us to develop a new differential sidechannel attack. More precisely, we build a distinguisher that uses the value of the Mutual Information between the observed measurements and a hypothetical leakage to rank key guesses. The attack is effective without any knowledge about the particular dependencies between measurements and leakage as well as between leakage and processed data, which makes it a universal tool. Our approach is confirmed by results of power analysis experiments. We demonstrate that the model and the attack work effectively in an attack scenario against DPAresistant logic.