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We construct an efficient dynamic group signature (or more generally an accountable ring signature) from isogeny and lattice assumptions. Our group signature is based on a simple generic construction that can be instantiated by cryptographically hard group actions such as the CSIDH group action or an MLWE-based group action. The signature is of size $$O(\log N)$$ O ( log N ) , where N is the number of users in the group. Our idea builds on the recent efficient OR-proof by Beullens, Katsumata, and Pintore (Asiacrypt’20), where we efficiently add a proof of valid ciphertext to their OR-proof and further show that the resulting non-interactive zero-knowledge proof system is online extractable. Our group signatures satisfy more ideal security properties compared to previously known constructions, while simultaneously having an attractive signature size. The signature size of our isogeny-based construction is an order of magnitude smaller than all previously known post-quantum group signatures (e.g., 6.6 KB for 64 members). In comparison, our lattice-based construction has a larger signature size (e.g., either 126 KB or 89 KB for 64 members depending on the satisfied security property). However, since the $$O(\cdot )$$ O ( · ) -notation hides a very small constant factor, it remains small even for very large group sizes, say $$2^{20}$$ 2 20 .

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Contemporary research exploring embodiment in music has suggested that creative musical thought is directly linked to a performer’s learnt physical techniques. Within this discourse, it is understood that an improvising musician’s embodied physical techniques play a primary role in informing their creative processes. This view suggests that subsequent changes or developments to a jazz musician’s physical technique may fundamentally influence the ways in which musical ideas are conceived while improvising. This article begins by unpacking a cross-section of literature in support of this claim, before presenting the results of a practice-led autoethnographic experiment exploring the relationship between instrumental technique and creative practice. In this experiment, I transition to a new way of playing the double bass, informed by Joel Quarrington’s The Canadian School of Double Bass, and observe transformations in hand frame, use of vertical shifts, use of register, feelings of tension and overall dexterity, all of which appear to influence my creative decision making. The results highlight how this reformed technical approach affected the physical accessibility of certain intervallic options, and appear to have fundamentally impacted my conception and construction of melodic content on a cognitive level.