We introduce a new cryptographic primitive: Proofs of SpaceTime (PoSTs) and construct a practical protocol for implementing these proofs. A PoST allows a prover to convince a verifier that she spent a “spacetime” resource (storing data—space—over a period of time). Formally, we define the PoST resource as a linear tradeoff between CPU work and space-time (under reasonable cost assumptions, a ra...

Abstract PudgyTurtle is not a cipher, but rather an alternative way to utilize the keystream in binary-additive stream-cipher cryptosystems. Instead of modulo-2 adding plaintext, uses encode 4-bit groups and then encipher each codeword. One goal make time–memory tradeoff attacks more difficult. Here, we investigate one such attack (a modification well-known Babbage–Golić method), show that its ...

Proactive Learning is a generalized form of active learning where the learner must reach out to multiple oracles exhibiting different costs and reliabilities (label noise). One of the its major goals is to capture the cost-noise tradeoff in oracle selection. Sequential active learning exhibits coarse accuracy at the beginning and progressively refine prediction at later stages. The ability to l...

Software engineering requires creativity, thorough design and analysis, and sound design decisions. Design decisions often have tradeoffs and implications associated with them. Therefore, it is important that design decisions are based on sound analysis. With respect to embedded systems, key drivers are often performance and cost. Thus the purpose of this paper is to describe an approach to aid...

We present a Kullback–Leibler (KL) control treatment of the fundamental problem of erasing a bit. We introduce notions of reliability of information storage via a reliability timescale τr, and speed of erasing via an erasing timescale τe. Our problem formulation captures the tradeoff between speed, reliability, and the KL cost required to erase a bit. We show that rapid erasing of a reliable bi...

Distributed storage systems are mainly justified due to the limited amount of storage capacity and improving the reliability through distributing data over multiple storage nodes. On the other hand, it may happen the data is stored in unreliable nodes, while it is desired the end user to have a reliable access to the stored data. So, in an event that a node is damaged, to prevent the system rel...