Trustless Distributed Symmetric-key Encryption
Threshold cryptography has gained momentum in the last decades as a mechanism to protect long term secret keys. Rather than having a single secret key, this allows to distribute the ability to perform a cryptographic operation such as signing or encrypting. Threshold cryptographic operations are sha...
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Main Authors | , , , , , |
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Format | Journal Article |
Language | English |
Published |
28.08.2024
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Subjects | |
Online Access | Get full text |
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Summary: | Threshold cryptography has gained momentum in the last decades as a mechanism
to protect long term secret keys. Rather than having a single secret key, this
allows to distribute the ability to perform a cryptographic operation such as
signing or encrypting. Threshold cryptographic operations are shared among
different parties such that a threshold number of them must participate in
order to run the operation. This makes the job of an attacker strictly more
difficult in the sense that they would have to corrupt at least a threshold
number of parties to breach the security. Most works in this field focus on
asymmetric-key schemes that allow threshold signing or decrypting.
We focus on the symmetric-key setting, allowing both threshold encryption and
threshold decryption. Previous work relies on the presence of a trusted third
party. Such a party may not exist in some use cases, and it represents a single
point of failure. We propose to remove the requirement of a trusted third party
by designing a dealer-free setup in which no entity can at any point obtain
full knowledge of the secret keys.
We implement a proof of concept of our construction in Python. We evaluate
the proof of concept with timing metrics to compare to theoretical expectations
and assess the cost in complexity of not relying on a trusted third party.
While the setup phase suffers moderate additional cost, the encryption and
decryption phases perform the same as the original algorithm. |
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DOI: | 10.48550/arxiv.2408.16137 |