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The main goal of traceable cryptography is to protect against unauthorized redistribution of cryptographic functionalities. Such schemes provide a way to embed identities (i.e., a “mark”) within cryptographic objects (e.g., decryption keys in an encryption scheme, signing keys in a signature scheme). In turn, the tracing guarantee ensures that any “pirate device” that successfully replicates the underlying functionality can be successfully traced to the set of identities used to build the device. In this work, we study traceable pseudorandom functions (PRFs). As PRFs are the workhorses of symmetric cryptography, traceable PRFs are useful for augmenting symmetric cryptographic primitives with strong traceable security guarantees. However, existing constructions of traceable PRFs either rely on strong notions like indistinguishability obfuscation or satisfy weak security guarantees like single-key security (i.e., tracing only works against adversaries that possess a single marked key). In this work, we show how to use fingerprinting codes to upgrade a single-key traceable PRF into a fully collusion resistant traceable PRF, where security holds regardless of how many keys the adversary possesses. We additionally introduce a stronger notion of security where tracing security holds even against active adversaries that have oracle access to the tracing algorithm. In conjunction with known constructions of single-key traceable PRFs, we obtain the first fully collusion resistant traceable PRF from standard lattice assumptions. Our traceable PRFs directly imply new lattice-based secret-key traitor tracing schemes that are CCA-secure and where tracing security holds against active adversaries that have access to the tracing oracle.
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This content will become publicly available on August 17, 2026
How to Make Any Computational Secret Sharing Scheme Adaptively Secure
Secret sharing (SS) is a foundational cryptographic primitive with diverse applications, including secure multiparty computation and conditional disclosure of secrets. While traditional schemes have primarily emphasized information-theoretic security, recent advancements have increasingly leveraged computational assumptions to achieve more efficient constructions and support broader access policies. Despite these successes, most existing computational secret sharing (CSS) schemes are limited to a static security model, where adversaries must commit to their choice of corrupted participants at the outset. A critical challenge in CSS lies in achieving adaptive security, where adversaries can dynamically select participants to corrupt, better reflecting real-world threat models. In this paper, we present a novel transformation that converts any statically secure CSS scheme into an adaptively secure one while preserving the original access policy and computational assumptions, providing a framework for bridging the gap between static and adaptive security. Our construction introduces a multiplicative share size overhead of where is the number of parties. Additionally, we explore trade-offs in efficiency and security, offering more efficient adaptive CSS constructions for specific, restricted policy classes. This work addresses key limitations in the current landscape of CSS and paves the way for broader adoption of adaptively secure secret sharing in cryptographic applications.
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- Award ID(s):
- 2318701
- PAR ID:
- 10613271
- Publisher / Repository:
- CRYPTO 2025
- Date Published:
- Format(s):
- Medium: X
- Location:
- Santa Barbara, CA, USA
- Sponsoring Org:
- National Science Foundation
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