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Chapter and Conference Paper
On the Equivalence of RSA and Factoring Regarding Generic Ring Algorithms
To prove or disprove the computational equivalence of solving the RSA problem and factoring integers is a longstanding open problem in cryptography. This paper provides some evidence towards the validity of th...
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Chapter and Conference Paper
A Hardware-Assisted Realtime Attack on A5/2 Without Precomputations
A5/2 is a synchronous stream cipher that is used for protecting GSM communication. Recently, some powerful attacks [2,5] on A5/2 have been proposed. In this contribution we enhance the ciphertext-only attack [...
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Chapter and Conference Paper
A Real-World Attack Breaking A5/1 within Hours
In this paper we present a real-world hardware-assisted attack on the well-known A5/1 stream cipher which is (still) used to secure GSM communication in most countries all over the world. During the last ten y...
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Chapter and Conference Paper
Faster Multi-exponentiation through Caching: Accelerating (EC)DSA Signature Verification
When verifying digital signatures, achieving a high throughput can be crucial. We present a technique that is useful for ECDSA and DSA signatures. It assumes that common domain parameters are used (which is ty...
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Chapter and Conference Paper
Time-Area Optimized Public-Key Engines: \(\mathcal{MQ}\) -Cryptosystems as Replacement for Elliptic Curves?
In this paper ways to efficiently implement public-key schemes based on ultivariate
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Chapter and Conference Paper
Reconfigurable Cryptography: A Flexible Approach to Long-Term Security
We put forward the concept of a reconfigurable cryptosystem. Intuitively, a reconfigurable cryptosystem allows to increase the security of the system at runtime, by changing a single central parameter we call com...
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Chapter and Conference Paper
Public-Key Encryption with Simulation-Based Selective-Opening Security and Compact Ciphertexts
In a selective-opening (SO) attack on an encryption scheme, an adversary \(A\) ...
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Chapter and Conference Paper
Onion Routing with Replies
Onion routing (OR) protocols are a crucial tool for providing anonymous internet communication. An OR protocol enables a user to anonymously send requests to a server. A fundamental problem of OR protocols is ...
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Chapter and Conference Paper
Universally Composable Auditable Surveillance
User privacy is becoming increasingly important in our digital society. Yet, many applications face legal requirements or regulations that prohibit unconditional anonymity guarantees, e.g., in electronic payme...