Key Wrap Algorithm.

Slides:

Advertisements

Similar presentations

Chapter 3 Public Key Cryptography and Message authentication.

Advertisements

ECE454/CS594 Computer and Network Security Dr. Jinyuan (Stella) Sun Dept. of Electrical Engineering and Computer Science University of Tennessee Fall 2011.

CS 483 – SD SECTION BY DR. DANIYAL ALGHAZZAWI (3) Information Security.

CS470, A.SelcukCryptographic Authentication1 Cryptographic Authentication Protocols CS 470 Introduction to Applied Cryptography Instructor: Ali Aydin Selcuk.

Random Number Generation Graham Netherton Logan Stelly.

Network Security. Confidentiality Using Symmetric Encryption John wrote the letters of the alphabet under the letters in its first lines and tried it.

CS457 – Introduction to Information Systems Security Cryptography 1b Elias Athanasopoulos

Cryptography and Network Security Chapter 7 Fifth Edition by William Stallings Lecture slides by Lawrie Brown.

CS555Spring 2012/Topic 161 Cryptography CS 555 Topic 16: Key Management and The Need for Public Key Cryptography.

© 2003 School of Computing, University of Leeds SY32 Secure Computing, Lecture 15 Implementation Flaws Part 3: Randomness and Timing Issues.

OOP/Java1 Public Key Crytography From: Introduction to Algorithms Cormen, Leiserson and Rivest.

Stream cipher diagram + + Recall: One-time pad in Chap. 2.

Public Key Crytography1 From: Introduction to Algorithms Cormen, Leiserson and Rivest.

ITIS 6200/8200. time-stamping services Difficult to verify the creation date and accurate contents of a digital file Required properties of time-stamping.

Public Key Cryptography

How cryptography is used to secure web services Josh Benaloh Cryptographer Microsoft Research.

Cryptography1 CPSC 3730 Cryptography Chapter 7 Confidentiality Using Symmetric Encryption.

CMSC 414 Computer (and Network) Security Lecture 24 Jonathan Katz.

8: Network Security8-1 Symmetric key cryptography symmetric key crypto: Bob and Alice share know same (symmetric) key: K r e.g., key is knowing substitution.

Cryptography and Network Security Chapter 7

Computer Security CS 426 Lecture 3

Genome Sciences 373 Genome Informatics Quiz Section 9 May

CSCI 172/283 Fall 2010 Public Key Cryptography. New paradigm introduced by Diffie and Hellman The mailbox analogy: Bob has a locked mailbox Alice can.

Lecture 4 Cryptographic Tools (cont) modified from slides of Lawrie Brown.

C HAPTER 13 Asymmetric Key Cryptography Slides adapted from "Foundations of Security: What Every Programmer Needs To Know" by Neil Daswani, Christoph Kern,

Codes, Ciphers, and Cryptography-RSA Encryption

Computer Science Public Key Management Lecture 5.

Cryptography and Network Security Chapter 7 Fifth Edition by William Stallings Lecture slides by Lawrie Brown.

Page 1 Secure Communication Paul Krzyzanowski Distributed Systems Except as otherwise noted, the content of this presentation.

Lecture 19 Page 1 CS 111 Online Symmetric Cryptosystems C = E(K,P) P = D(K,C) E() and D() are not necessarily the same operations.

Lecture 7b: The Diffie-Hellman Secret Sharing Scheme Wayne Patterson SYCS 653 Fall 2009.

Cryptography and Network Security Chapter 7 Fifth Edition by William Stallings.

Cryptography and Network Security (CS435)

CS555Spring 2012/Topic 51 Cryptography CS 555 Topic 5: Pseudorandomness and Stream Ciphers.

Public-Key Cryptography CS110 Fall Conventional Encryption.

How cryptography is used to secure web services Josh Benaloh Cryptographer Microsoft Research.

Network Security Lecture 19 Presented by: Dr. Munam Ali Shah.

Information Security Lab. Dept. of Computer Engineering 182/203 PART I Symmetric Ciphers CHAPTER 7 Confidentiality Using Symmetric Encryption 7.1 Placement.

Day 37 8: Network Security8-1. 8: Network Security8-2 Symmetric key cryptography symmetric key crypto: Bob and Alice share know same (symmetric) key:

Cryptography Wei Wu. Internet Threat Model Client Network Not trusted!!

8-1 Chapter 8 Security Computer Networking: A Top Down Approach 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012.

Cryptography and Network Security (CS435) Part Eight (Key Management)

Cryptography and Network Security Chapter 10 Fifth Edition by William Stallings Lecture slides by Lawrie Brown.

Public Key Cryptography. symmetric key crypto requires sender, receiver know shared secret key Q: how to agree on key in first place (particularly if.

Chapter 7 – Confidentiality Using Symmetric Encryption.

Chapter 7 Confidentiality Using Symmetric Encryption.

Cryptography and Network Security Key Distribution for Symmetric Encryption.

PUBLIC-KEY CRYPTOGRAPH IT 352 : Lecture 2- part3 Najwa AlGhamdi, MSc – 2012 /1433.

Chapter 3 (B) – Key Management; Other Public Key Cryptosystems.

Attacks on PRNGs - By Nupura Neurgaonkar CS-265 (Prof. Mark Stamp)

PUBLIC KEY CRYPTOGRAPHY ALGORITHM Concept and Example 1IT352 | Network Security |Najwa AlGhamdi.

Cryptographic Hash Functions and Protocol Analysis

Lecture 14 Page 1 CS 236 Online Race Conditions A common cause of security bugs Usually involve multiprogramming or multithreaded programs Caused by different.

Authentication. Goal: Bob wants Alice to “prove” her identity to him Protocol ap1.0: Alice says “I am Alice” Failure scenario?? “I am Alice”

Network Security Lecture 18 Presented by: Dr. Munam Ali Shah.

+ Security. + What is network security? confidentiality: only sender, intended receiver should “understand” message contents sender encrypts message receiver.

PRNGs Pseudo-random number generation. Randomness and Cryptography Randomness and pseudo-randomness are useful in cryptography: –To generate random and.

Fall 2006CS 395: Computer Security1 Confidentiality Using Symmetric Encryption.

Homework #1 J. H. Wang Oct. 2, 2013.

Software Security Seminar - 1 Chapter 4. Intermediate Protocols 발표자 : 이장원 Applied Cryptography.

Wired Equivalent Privacy (WEP) Chris Overcash. Contents What is WEP? What is WEP? How is it implemented? How is it implemented? Why is it insecure? Why.

Chapter 7 – Confidentiality Using Symmetric Encryption.

Diffie-Hellman Key Exchange first public-key type scheme proposed by Diffie & Hellman in 1976 along with the exposition of public key concepts – note:

Cryptography services Lecturer: Dr. Peter Soreanu Students: Raed Awad Ahmad Abdalhalim

Understanding Cryptography – A Textbook for Students and Practitioners by Christof Paar and Jan Pelzl Chapter 2 – Stream Ciphers These slides were.

CPIS 312 Chapter Five: Hash Function By Dr. Daniyal Alghazzawi 2011 Term 2.

Homework #1 J. H. Wang Oct. 9, 2012.

Understanding Cryptography – A Textbook for Students and Practitioners by Christof Paar and Jan Pelzl Chapter 2 – Stream Ciphers.

CSC 110 – Fluency in Information Technology Chapter 20: The random function and Chaos Dr. Curry Guinn.

Pseudorandom Numbers Network Security.

Presentation transcript:

Key Wrap Algorithm

Key wrap algorithm Key wrap algorithm Types of key wrap algorithms Even when a user encrypts message by using symmetric key algorithm, he has two keys; one is called key encryption key(KEK) which is used for encrypting the content encryption key(CEK) which is use for encrypting message. And then send encrypted CEK and encrypted message. Types of key wrap algorithms AESKW(AES key wrapping algorithm) TDKW (TDES key wrapping algorithm) AKW1 AKW2

Simplified AESKW Bob Alice KEKAB KEKAB generate CEKAB encrypt CEKAB : Ckey=EKEKAB(CEKAB) Message: x encrypt message: c=ECEKAB(x) KEKAB (Ckey, c) decrypt Ckey : CEKAB=EKEKAB(Ckey) decrypt message: x=ECEKAB(c)

Purpose of key wrapping For more security? In my opinion, there is no point of key wrapping for providing more security. If KEK is revealed, so is the message. But there is one advantage: Suppose Bob maintains encrypted data communicated up to now. Even if KEK is revealed, he doesn’t need to change the CEK. Instead, Alice re-encrypts the same CEK with new KEK and sends the newly encrypted CEK to Bob.

Random Number Generation (RNG)

Types of RNG True RNG Pseudo RNG Random numbers are generated from physical process in real life. Eg, coin flipping, lottery, thermal noise, mouse movement, etc. Pseudo RNG Random numbers are computed, i.e. they are deterministic. Typical algorithm for computing PRNG S0=seed, Si+1 = F(Si) Eg, RAND() function in ANSI C S0=12345, Si+1 = 1103515245 Si + 12345 (mod 231)

Types of RNG Cryptography PRNG (CPRNG) CPRNGs are PRNG with one additional property; generated numbers are unpredictable. Given n output bits Si, Si+1, …, Si+n-1 It is computationally infeasible to generate Sn.

Uses of Random Numbers Random numbers used to generate keys Symmetric keys RSA: Prime numbers Diffie Hellman: secret values Random numbers used for nonces Sometimes a sequence is OK But sometimes nonces must be random Random numbers also used in simulations, statistics, etc. Such numbers need to be “statistically” random

Case: Misuse of Random Numbers Online version of Texas Hold ‘em Poker ASF Software, Inc. Random numbers used to shuffle the deck Program did not produce a random shuffle A serious problem or not?

Card Shuffle There are 52! > 2225 possible shuffles The poker program used “random” 32-bit integer to determine the shuffle So, only 232 distinct shuffles could occur Code used Pascal pseudo-random number generator (PRNG): Randomize() Seed value for PRNG was function of number of milliseconds since midnight Less than 227 milliseconds in a day So, less than 227 possible shuffles

Card Shuffle Seed based on milliseconds since midnight PRNG re-seeded with each shuffle By synchronizing clock with server, number of shuffles that need to be tested  218 Could then test all 218 in real time Test each possible shuffle against “up” cards Attacker knows every card after the first of five rounds of betting!

Poker Example Poker program is an extreme example But common PRNGs are predictable Only a question of how many outputs must be observed before determining the sequence Crypto random sequences not predictable For example, keystream from RC4 cipher But “seed” (or key) selection is still an issue! How to generate initial random values? Keys (and, in some cases, seed values)

Randomness Sources of randomness via software Software is (hopefully) deterministic So must rely on external “random” events Mouse movements, keyboard dynamics, network activity, etc., etc. Can get quality random bits by such methods But quantity of bits is very limited Bottom line: “The use of pseudo-random processes to generat e secret quantities can result in pseudo-security”