Views
5 years ago

# x - Faculty of Computer Science - Technische Universität Dresden

x - Faculty of Computer Science - Technische Universität Dresden

## (3)�(4) is clear with

(3)�(4) is clear with const':= W(S). Conversely, we show const' = W(S): W ( S) � � � � x � x W ( x) � W ( x) � const' � const'. Proof (4) is already quite the same as (1): In general holds W(S|x) = W({k | k(x) = S}), and if all keys have the same probability, W(S|x)= |{k | k(x) = S}| / |K|. Then (4) is equivalent (1) with � � const = const' • |K|. x W(S|x) const' W ( x) 157

Another definition for information-theoretical security Sometimes, students come up with the following definition: �S � S �x � X: W(S) = W(S|x). This is not equivalent, but a slight modification is: 3. Definition �S � S �x � X with W(x)>0: W(S) = W(S|x). Definitions 2. and 3. are equivalent: Remember Bayes: W ( x) �W ( S | x) W ( x | S) � W ( S) W(x|S) = W(x) (Bayes) W ( x) �W ( S | x) ( x | S) � W ( S) W(S|x) = W(S) = W(x) (if W(x) ≠0, we can divide by W(x)) W(S|x) as proposed by some students assumes that x may be sent, i.e. W(x)>0. 158

faculty of computer science - Fakultät Informatik - Technische ...
Slides - Technische Universität Dresden
Statistics beyond Physics - Technische Universität Dresden
OCL By Example Lecture - Technische Universität Dresden
Graphs - Www-st.inf.tu-dresden.de - Technische Universität Dresden
Optimierung und Frustration: - Technische Universität Dresden
2. Mobile Internet - Faculty of Computer Science - Technische ...
Talk - Technische UniversitÃ¤t Dresden
5. Adaptation - Faculty of Computer Science - Technische ...
3. Adaptation - Faculty of Computer Science - Technische ...
02 - Technische UniversitÃ¤t Dresden
3. Mobile Internet - Faculty of Computer Science - Technische ...
4. Context Awareness - Faculty of Computer Science - Technische ...
Wiki Event Navigation - Computer Networks - Technische Universität ...
Content Sharing - Technische UniversitÃ¤t Dresden
7. Location-based Se.. - Faculty of Computer Science - Technische ...
SAP AG - Faculty of Computer Science
6. Context Awareness - Faculty of Computer Science - Technische ...
Computer Science and Engineering - Technische Universiteit ...
5. Location-based Se.. - Faculty of Computer Science - Technische ...
Folie 1 - Faculty of Computer Science
Folie 1 - Faculty of Computer Science
First Presentation - Faculty of Computer Science
Folie 1 - Faculty of Computer Science
X - Technische Universität Dresden
X - Technische Universität Dresden
diplomarbeit - Computer Networks - Technische Universität Dresden
Technische Universität Dresden - Computer Networks - Technische ...
M - Technische Universität Dresden
TRANSCRIPT OF RECORDS - Technische Universität Dresden