Oblivious Lookup-Tables

Wamser, Markus S.; Raß, Stefan; Schartner, Peter

doi:10.1515/tmmp-2016-0039

Cited by 2 publications

(3 citation statements)

References 13 publications

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“…Besides the simple use of putting information into a ciphertext, we may also have practical use for manipulating the ciphertext; of course, contingent upon the knowledge of one (or more) secret keys. The usual practical method is using a (fully) homomorphic encryption; a simple example of which is [31], which also allows to decipher a string into several different plaintexts using different extraction secrets, but does not allow changing any content. Our construction is, however, essentially different from this, since the ability of putting new messages into a ciphertext c also lets us replace messages arbitrarily, provided that we have the respective decryption key.…”

Section: B Encryptionmentioning

confidence: 99%

False-Bottom Encryption: Deniable Encryption From Secret Sharing

2023

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We show how to implement a deniable encryption method from secret sharing. Unlike the related concept of honey encryption, which employs a preprocessing step in symmetric encryption to re-shape the distribution of a plaintext towards making the real plaintext indistinguishable from a ciphertext for a fake message, we can avoid both, computational intractability assumptions and preprocessing of the data. This accomplishes deniability against an attacker that can force decryptions, and it can brute-force break a ciphertext with sufficient computational power. Following the concept of plausible deniability, we herein have different decryption keys to open up distinct plaintexts from within the same ciphertext. For instance, a plaintext revealed from a ciphertext with a key which was shared by a victim under duress, will convince the attacker that it is real, while the actual secret remains unnoticed. False Bottom Encryption constructs a symmetric scheme (in the sense of using the same key to encrypt and decrypt) that shares the properties of both honey encryption and deniable encryption. We specifically formalize and differentiate ''deniable'' from ''plausibly deniable'' as a security feature, showing how plausible deniability falls back to (only) deniability, depending on the plaintext distribution. Our scheme is simple, lightweight to implement and efficient in terms of encryption and decryption, and is based on secret sharing. As such, we do not rely on computational intractability. We corroborate the construction by giving numeric examples and providing implementations of the method as a Jupyter notebook supplementary to this work.

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Section: B Encryptionmentioning

confidence: 99%

False-Bottom Encryption: Deniable Encryption From Secret Sharing

2023

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“…The result of this function is again an encrypted number. A promising approach that can achieve this was presented by Wamser et al [36] in their work on "oblivious lookup-tables".…”

Section: Transfer Functionmentioning

confidence: 99%

“…Hence, the crucial part is to find an approach to extrapolate every vector v i only from one single x i so that the v i are linearly independent from each other. Wamser et al [36] suggest to use a Vandermonde-Matrix as V (Equation 3), because it fulfills these requirements.…”

Section: Oblivious Lookup Tablesmentioning

confidence: 99%