PPT-Secrecy of (fixed-length) stream ciphers

Author : alexa-scheidler | Published Date : 2017-07-12

Thm If G is a PRG then the fixedlength stream cipher Gen Enc Dec described below has indistinguishable encryptions in the presence of an eavesdropper 0

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Secrecy of (fixed-length) stream ciphers: Transcript

Thm If G is a PRG then the fixedlength stream cipher Gen Enc Dec described below has indistinguishable encryptions in the presence of an eavesdropper 0 Plaintexts and . 21 Fig 21 Main areas within cryptography This chapter gives an introduction to stream ciphers The pros and cons of stream ciphers Random and pseudorandom number generators A truly unbreakable cipher the OneTime Pad OTP Linear feedback shift register Pseudorandom Generators. Online Cryptography Course Dan Boneh. Review. Cipher over (K,M,C): a pair of “efficient” . algs. (. E. , . D. ) . s.t.. . ∀ . Demijan. . Klinc. * . Carmit. . Hazay. † . Ashish. . Jagmohan. **. Hugo . Krawczyk. ** . Tal Rabin. **. * . Georgia . Institute of . Technology. ** . IBM T.J. Watson Research . Labs. † . Rice ELEC 528/ COMP 538 . Farinaz Koushanfar. Spring 2009. 2. Summary. Substitution ciphers. Permutations. Making good ciphers . DES. AES. Slides are courtesy of Leszek T. Lilien from WMich. http://www.cs.wmich.edu/~llilien/. /B. 609. :. . Introduction to. Cryptography. Fall 2015 . . Lecture 7. . Last Thursday’s lecture:. Quiz. Computationally secret . encryption. Today’s lecture:. Pseudorandom generators (PRGs). 3b. . Pseudorandomness. .. B. ased on: Jonathan . Katz and Yehuda . Lindell. . Introduction . to . Modern Cryptography. 2. Pseudorandomness. An introduction. A distribution . D. is pseudorandom if no PPT . The One Time Pad. Online Cryptography Course Dan Boneh. Symmetric Ciphers: definition. Def. : a . cipher. defined over . . is a pair of “efficient” . algs. Stream ciphers are semantically secure. Online Cryptography Course Dan Boneh. Goal: secure PRG ⇒ semantically secure stream cipher. Stream ciphers are semantically secure. Headwaters. Important?. Before we start, just a reminder from . What are Headwaters? …. In general, headwater streams are . 1. st. , 2. nd. , and 3. rd. order streams . and their catchments, and …. Substitution. Classical Ciphers. Transposition. Data Encryption Standard 1977. Modern Cryptography. “New Directions in Cryptography” 1976. Symmetric . key block ciphers. Public key ciphers. Stream ciphers. Cryptography Lecture 1 0 A fixed-length MAC Construction Let F be a length-preserving pseudorandom function (aka block cipher) Construct the following MAC  : Gen: choose a uniform key k for F Mac DES, AES . TEK4500. 01.09.2020 . Håkon Jacobsen. hakon.jacobsen@its.uio.no. Ideal solution: secure channels. 2. Internet. Alice. Bob. M. Adversary. Security goals:. Data privacy: . adversary should not be able to read message M . Online Cryptography Course Dan Boneh. Symmetric Ciphers: definition. Def. : a . cipher. defined over . . is a pair of “efficient” . algs. (. E. , . D. Faculty of Engineering Stream Cipher Course name: Data Encryption. Computer Engineering Dep. Lecturer: Fatimah Al-.

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