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  • Oct
    7

    Seminar: Phuoc Pham Van Long

    Department of Computer Science (CS)

    11:00 AM 3501, Mudd Hall ( formerly Seeley G. Mudd Library)

    EVENT DETAILS

    Title: Mosaic: A Modular Framework for Private Fuzzy Heavy Hitters

    Abstract: We present Mosaic, a modular cryptographic framework for Private Fuzzy Heavy Hitters Detection, a new problem introduced and formalized in this work. In this problem, a service provider aims to identify the most frequent items (i.e., heavy hitters) in private client data without learning any individual client's data. Motivated by real-world applications where inputs are inherently noisy, we consider fuzzy heavy hitters that are close to a sufficiently large number of client data points under a chosen distance metric.

    Mosaic operates in the setting with two non-colluding servers and supports both the known-dictionary setting (where candidate fuzzy heavy hitters are fixed in advance) and the unknown-dictionary setting (where popular items must be discovered). The framework proceeds in two phases: during the upload phase, each client shares an encoding of their input with each server; in the fuzzy matching phase, the servers jointly identify fuzzy heavy hitters without learning any additional information about individual client's data.

    In the upload phase, Mosaic introduces a new cryptographic primitive called Property-Based Function Secret Sharing (PB-FSS), which relaxes the standard notion of FSS (Boyle et al., Eurocrypt 2015) in that the outputs of the FSS evaluations satisfy a certain property, rather than forming exact additive secret shares of the function output. We present a suite of new PB-FSS constructions for the L_inf and L_p distance metrics from lightweight cryptographic techniques.Furthermore, we introduce new methods to prevent malicious client behavior by detecting malformed PB-FSS shares. In the fuzzy matching phase, Mosaic presents two approaches, one involving only the two servers, and one involving an additional trusted dealer to improve efficiency. All parties are assumed to be semi-honest during the fuzzy matching phase.

    Finally, we implement Mosaic and evaluate it using real-world trace data from a ride-sharing service. In one scenario, Mosaic servers discovered over a thousand of the most popular ride start locations among 21 thousand users within 30-90 seconds.
    On the user side, the protocol requires only lightweight computation (as low as 0.14 millisecond) and communication (as low as 9 KB).

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    TIME Wednesday, October 7, 2026 at 11:00 AM - 12:00 PM

    LOCATION 3501, Mudd Hall ( formerly Seeley G. Mudd Library)    map it

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    CONTACT Wynante R Charles    wynante.charles@northwestern.edu EMAIL

    CALENDAR Department of Computer Science (CS)

  • Oct
    9

    CS Seminar: Teaching an LLM Tutor to Withhold the Answer (Yusuf Pisan)

    Department of Computer Science (CS)

    12:00 PM TCHL361, Technological Institute

    EVENT DETAILS

    TIME Friday, October 9, 2026 at 12:00 PM - 1:00 PM

    LOCATION TCHL361, Technological Institute    map it

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    CONTACT Wynante R Charles    wynante.charles@northwestern.edu EMAIL

    CALENDAR Department of Computer Science (CS)

  • Oct
    13

    Theory Seminar: (Ravi Kannan) Learning Mixtures with separation based on latent dimension

    Department of Computer Science (CS)

    1:00 PM 3514, Mudd Hall ( formerly Seeley G. Mudd Library)

    EVENT DETAILS

    TIME Tuesday, October 13, 2026 at 1:00 PM - 2:00 PM

    LOCATION 3514, Mudd Hall ( formerly Seeley G. Mudd Library)    map it

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    CONTACT Indira Munoz    indira.munoz@northwestern.edu EMAIL

    CALENDAR Department of Computer Science (CS)

  • Oct
    14

    CS/ECE Seminar: Programming and Architecting Heterogeneous Physical Intelligence: A Sensing-Computing-Human Co-Optimization Approach (Yuhao Zhu)

    Department of Computer Science (CS)

    12:00 PM 3514, Mudd Hall ( formerly Seeley G. Mudd Library)

    EVENT DETAILS

    TIME Wednesday, October 14, 2026 at 12:00 PM - 1:00 PM

    LOCATION 3514, Mudd Hall ( formerly Seeley G. Mudd Library)    map it

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    CONTACT Wynante R Charles    wynante.charles@northwestern.edu EMAIL

    CALENDAR Department of Computer Science (CS)

  • Oct
    21

    SkAI Colloquium

    SkAI Institute

    11:00 AM Auditorium

    EVENT DETAILSmore info

    TIME Wednesday, October 21, 2026 at 11:00 AM - 12:00 PM

    LOCATION Auditorium   

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    CONTACT Gema Tinoco    Gema.Tinoco@northwestern.edu EMAIL

    CALENDAR SkAI Institute

  • Oct
    22

    Bagel Thursday + Discussion

    Department of Computer Science (CS)

    9:00 AM 3514, Mudd Hall ( formerly Seeley G. Mudd Library)

    EVENT DETAILS

    TIME Thursday, October 22, 2026 at 9:00 AM - 11:00 AM

    LOCATION 3514, Mudd Hall ( formerly Seeley G. Mudd Library)    map it

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    CONTACT Wynante R Charles    wynante.charles@northwestern.edu EMAIL

    CALENDAR Department of Computer Science (CS)

  • Oct
    28

    CS Seminar: Aaron Shaw

    Department of Computer Science (CS)

    12:00 PM 3514, Mudd Hall ( formerly Seeley G. Mudd Library)

    EVENT DETAILS

    TIME Wednesday, October 28, 2026 at 12:00 PM - 1:00 PM

    LOCATION 3514, Mudd Hall ( formerly Seeley G. Mudd Library)    map it

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    CONTACT Wynante R Charles    wynante.charles@northwestern.edu EMAIL

    CALENDAR Department of Computer Science (CS)

  • Oct
    29

    Computer Science Halloween Crafting Social

    Department of Computer Science (CS)

    2:00 PM 3514, Mudd Hall ( formerly Seeley G. Mudd Library)

    EVENT DETAILS

    TIME Thursday, October 29, 2026 at 2:00 PM - 4:00 PM

    LOCATION 3514, Mudd Hall ( formerly Seeley G. Mudd Library)    map it

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    CONTACT Bella Barrios    marbella.barrios@northwestern.edu EMAIL

    CALENDAR Department of Computer Science (CS)

  • Nov
    4

    CS Seminar: Computational Ecosystems: Advancing Human Values Through Integrative Computing and Changing Practice (Haoqi Zhang)

    Department of Computer Science (CS)

    12:00 PM 3514, Mudd Hall ( formerly Seeley G. Mudd Library)

    EVENT DETAILS

    TIME Wednesday, November 4, 2026 at 12:00 PM - 1:00 PM

    LOCATION 3514, Mudd Hall ( formerly Seeley G. Mudd Library)    map it

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    CONTACT Wynante R Charles    wynante.charles@northwestern.edu EMAIL

    CALENDAR Department of Computer Science (CS)

  • Nov
    9

    Distinguished Lecture: Mohit Bansal

    Department of Computer Science (CS)

    12:00 PM 3514, Mudd Hall ( formerly Seeley G. Mudd Library)

    EVENT DETAILS

    TIME Monday, November 9, 2026 at 12:00 PM - 1:00 PM

    LOCATION 3514, Mudd Hall ( formerly Seeley G. Mudd Library)    map it

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    CONTACT Wynante R Charles    wynante.charles@northwestern.edu EMAIL

    CALENDAR Department of Computer Science (CS)

  • Nov
    19

    Bagel Thursday + Discussion

    Department of Computer Science (CS)

    9:00 AM 3514, Mudd Hall ( formerly Seeley G. Mudd Library)

    EVENT DETAILS

    TIME Thursday, November 19, 2026 at 9:00 AM - 11:00 AM

    LOCATION 3514, Mudd Hall ( formerly Seeley G. Mudd Library)    map it

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    CONTACT Wynante R Charles    wynante.charles@northwestern.edu EMAIL

    CALENDAR Department of Computer Science (CS)

  • Dec
    4

    Holiday Party

    Department of Computer Science (CS)

    12:00 PM

    EVENT DETAILS

    TIME Friday, December 4, 2026 at 12:00 PM - 2:00 PM

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    CONTACT Wynante R Charles    wynante.charles@northwestern.edu EMAIL

    CALENDAR Department of Computer Science (CS)