meta user
network profile
| bio | website | wallutis.de |
|---|---|---|
| location | Germany | |
| age | 48 | |
| visits | member for | 6 months |
| seen | Dec 29 '12 at 22:10 | |
| stats | profile views | 3 |
Im working as an IT Consultant (mainly Microsoft Exchange). Interested in mathematics, IT security and cryptography.
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Dec 28 |
awarded | Teacher |
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Dec 27 |
awarded | Supporter |
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Dec 27 |
answered | What exactly is a negligible (and non-negligible) function? |
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Dec 23 |
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Looking for examples for “proof by reduction” The only problem: this solution looks too easy... |
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Dec 23 |
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Looking for examples for “proof by reduction” Sorry for the delay; end-of-year stress;-) Here is my answer (so far i have no response; so i dont know if it is correct): Lets assume that A' is not collision-resistent. We write H'=H(y) instead of H'=H(H(x)). Then "collision-resistant" means: there exists y,y' with H(y)=H(y'), y<>y' When we now look at A, then H: {0,1}* -> {0,1}^l (arbitrary length -> fixed-length l) H': {0,1}^l -> {0,1}^l (fixed-length -> fixed-length) If H' is not collision-resistant, then we have y,y' with H(y)=H(y'). That is a special case of H and that would mean that H is not collision-resistant too. |
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Nov 25 |
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Looking for examples for “proof by reduction” @Ricky: You are (formally) right. I have no idea how to add an upper s to H;-) But it is correct: in the line with H'(x)=H(H(x)) there are upper s missing on H. In "Katz/Lindell: Introduction to modern cryptography (Page 129)" (Gen, H) is called a Hash function in the definition; but its mentioned in the text that it is a familiy of Hash functions and s picks one function. |
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Nov 25 |
asked | Looking for examples for “proof by reduction” |
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Nov 25 |
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Pseudorandom generator and AE-secure encryption not really homework. These is from a list of exam question that i need to understand. Its one question on a list of 6 multiple choice question. In the exam it wasnt necessary to give an explanation, but i want to understand it. |
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Nov 24 |
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Pseudorandom generator and AE-secure encryption I try to translate the definition of AE-secure that is in my lecture notes: An encryption scheme is AE-secure, if it is secure against Chosen-cyphertext attacks and provides authenticity. |
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Nov 24 |
awarded | Autobiographer |
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Nov 24 |
awarded | Student |
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Nov 24 |
asked | Pseudorandom generator and AE-secure encryption |
