Questions tagged [reduction]

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2 answers
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Security reduction seems to wrongly show that a non-PRF is a PRF

This is a well-known exercise that has already even been posted here. I understand both arguments to prove and disprove that $F'$ and $\bar{F}$ are PRFs, as I explain below, however, it seems that the ...
  • 254
3 votes
1 answer
64 views

In reduction from search LWE to decsion LWE why sampling needs to repeat a polynomial number of times?

I've been reading through MIT's lecture notes on learning with errors here, and I'm trying to understand the reduction from Search LWE to Decision LWE, as described there in Section 2.7, "...
  • 311
1 vote
1 answer
65 views

Private key encryption based on NP-complete problem

Over a decade ago, a question was asked on Stack Overflow, which basically asked if there were any encryption schemes that are reducible to an NP-complete problem, in the sense that breaking the ...
0 votes
0 answers
51 views

How to reduce Diffie Hellman problem to ElGamal?

I'm trying to answer without success questions (ii - iv) Any hint will be appreciated :)
2 votes
0 answers
50 views

Meta Reduction in Fiat Shamir Transformation

What is meant by meta reduction? What does it achieve and how is it different from the normal reduction technique?
1 vote
0 answers
46 views

polynomial time reduction from SIS to decisional-LWE?

Is the claim "If there is an efficient algorithm that solves SIS, then there is an efficient algorithm that solves decisional LWE" is sufficient? or, Is the claim above is equivalent to the ...
  • 11
1 vote
0 answers
45 views

Provable security: impossible reduction when messages are encrypted/semantic security with function depending on the output of adversary

I've a problem with a protocol for which I can prove the security if the messages sent by the adversary are sent in clear, but I can't prove the security anymore if the messages sent by the adversary ...