Views
5 years ago

# x - Faculty of Computer Science - Technische Universität Dresden

x - Faculty of Computer Science - Technische Universität Dresden

## Method s 2

Method s 2 -mod-n-generator • key value: p,q prime, big, � 3 mod 4 n = p • q • initial value (seed): s � Z n * • PBG: s 0 := s 2 mod n Example: n = 3 � 11 = 33, s = 2 index 0 1 2 3 4 s i : b i : s i+1 := s i 2 mod n bi := s i mod 2 ... (last bit) Note: length of period no problem with big numbers (Blum / Blum / Shub 1983 / 86) ... 4 16 25 31 4 0 0 1 1 0 16 2 mod 33 = 8 � 32 = 8 � (-1) = 25 25 2 = (-8) 2 � 64 � 31 31 2 = (-2) 2 = 4 185

s 2 -mod-n-generator as symmetric encryption system Purpose: application as symmetric encryption system: “Pseudo one-time pad” Compare: one-time pad: add long real random bit stream with plaintext Pseudo one-time pad: add long pseudo-random stream with plaintext Scheme: secret area n, s security- parameter secret key = key and initial value = x0x1x2 ... encryption: create b0 b1 b2 ..., add = x0 � b0, x1 � b1, ... key generation = generation of key and initial value n, s plaintext ciphertext plaintext decryption: create b0 b1 b2 ..., add real random number x k(x) x l 186

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