Abstract. We study the security of symmetric encryption schemes in settings with multiple users and realistic adversaries who can adaptively corrupt encryption keys. To avoid confinement to any particular definitional paradigm, we propose a general framework for multi-key security definitions. By appropriate settings of the parameters of the framework, we obtain multi-key variants of many of the existing single-key security notions. This framework is instrumental in establishing our main results. We show that for all single-key secure encryption schemes satisfying a minimal key uniqueness assumption and almost any instantiation of our general multi-key security notion, any reasonable reduction from the multi-key game to a standard single-key game necessarily incurs a linear loss in the number of keys. We prove this result for all three classical single-key security notions capturing confidentiality, authenticity and the combined authenticated encryption notion.
Abstract. Cryptographic APIs like PKCS#11 are interfaces to trusted hardware where keys are stored; the secret keys should never leave the trusted hardware in plaintext. In PKCS#11 it is possible to give keys conflicting roles, leading to a number of key-recovery attacks. To prevent these attacks, one can authenticate the attributes of keys when wrapping, but this is not standard in PKCS#11. Alternatively, one can configure PKCS#11 to place additional restrictions on the commands permitted by the API. Bortolozzo et al. proposed a configuration of PKCS#11, called the Secure Templates Patch (STP), supporting symmetric encryption and key wrapping. However, the security guarantees for STP given by Bortolozzo et al. are with respect to a weak attacker model. STP has been implemented as a set of filtering rules in Caml Crush, a software filter for PKCS#11 that rejects certain API calls. The filtering rules in Caml Crush extend STP by allowing users to compute and verify MACs and so the previous analysis of STP does not apply to this configuration. We give a rigorous analysis of STP, including the extension used in Caml Crush. Our contribution is as follows: (i) We show that the extension of STP used in Caml Crush is insecure.(ii) We propose a strong, computational security model for configurations of PKCS#11 where the adversary can adaptively corrupt keys and prove that STP is secure in this model. (iii) We prove the security of an extension of STP that adds support for public-key encryption and digital signatures.
Abstract. Cryptographic APIs like PKCS#11 are interfaces to trusted hardware where keys are stored; the secret keys should never leave the trusted hardware in plaintext. In PKCS#11 it is possible to give keys conflicting roles, leading to a number of key-recovery attacks. To prevent these attacks, one can authenticate the attributes of keys when wrapping, but this is not standard in PKCS#11. Alternatively, one can configure PKCS#11 to place additional restrictions on the commands permitted by the API. Bortolozzo et al. proposed a configuration of PKCS#11, called the Secure Templates Patch (STP), supporting symmetric encryption and key wrapping. However, the security guarantees for STP given by Bortolozzo et al. are with respect to a weak attacker model. STP has been implemented as a set of filtering rules in Caml Crush, a software filter for PKCS#11 that rejects certain API calls. The filtering rules in Caml Crush extend STP by allowing users to compute and verify MACs and so the previous analysis of STP does not apply to this configuration. We give a rigorous analysis of STP, including the extension used in Caml Crush. Our contribution is as follows: (i) We show that the extension of STP used in Caml Crush is insecure.(ii) We propose a strong, computational security model for configurations of PKCS#11 where the adversary can adaptively corrupt keys and prove that STP is secure in this model. (iii) We prove the security of an extension of STP that adds support for public-key encryption and digital signatures.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.