Hashing (Message Digest). ............ ............ Hello There.

Slides:

Advertisements

Similar presentations

Hashes and Message Digests

Advertisements

Hash Functions A hash function takes data of arbitrary size and returns a value in a fixed range. If you compute the hash of the same data at different.

Lecture 5: Cryptographic Hashes

Hash Function. What are hash functions? Just a method of compressing strings – E.g., H : {0,1}*  {0,1} 160 – Input is called “message”, output is “digest”

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

Digital Signatures and Hash Functions. Digital Signatures.

PIITMadhumita Chatterjee Security 1 Hashes and Message Digests.

1 Chapter 5 Hashes and Message Digests Instructor: 孫宏民 Room: EECS 6402, Tel: , Fax :

Hash functions a hash function produces a fingerprint of some file/message/data h = H(M)  condenses a variable-length message M  to a fixed-sized fingerprint.

Chapter 4  Hash Functions 1 Overview  Cryptographic hash functions are functions that: o Map an arbitrary-length (but finite) input to a fixed-size output.

Information Security and Management 11

Secure Hashing and DSS Sultan Almuhammadi ICS 454 Principles of Cryptography.

ITIS 3200: Introduction to Information Security and Privacy Dr. Weichao Wang.

CS526Topic 5: Hash Functions and Message Authentication 1 Computer Security CS 526 Topic 5 Cryptography: Cryptographic Hash Functions And Message Authentication.

Cryptography1 CPSC 3730 Cryptography Chapter 11, 12 Message Authentication and Hash Functions.

1 Message Authentication and Hash Functions Authentication Requirements Authentication Functions Message Authentication Codes Hash Functions Security of.

CRYPTOGRAPHIC DATA INTEGRITY ALGORITHMS

Network Security Chapter Computer Networks, Fifth Edition by Andrew Tanenbaum and David Wetherall, © Pearson Education-Prentice Hall, 2011.

Cryptography and Network Security Chapter 11 Fifth Edition by William Stallings Lecture slides by Lawrie Brown.

Acknowledgements: William Stallings.William Stallings All rights Reserved Session 4 Public Key Cryptography (Part 2) Network Security Essentials Application.

Message Authentication  message authentication is concerned with: protecting the integrity of a message protecting the integrity of a message validating.

Information Security Principles Assistant Professor Dr. Sana’a Wafa Al-Sayegh 1 st Semester ITGD 2202 University of Palestine.

1 Chapter 11: Message Authentication and Hash Functions Fourth Edition by William Stallings Lecture slides by Lawrie Brown (modified by Prof. M. Singhal,

Monitor's Secret Key Crypto - KARN, encrypt 512 bit Secret.

1 Hashes and Message Digests. 2 Hash Also known as –Message digest –One-way function Function: input message -> output One-way: d=h(m), but not h’(d)

Module 3 – Cryptography Cryptography basics Ciphers Symmetric Key Algorithms Public Key Algorithms Message Digests Digital Signatures.

Message Authentication and Hash Functions Chapter 11.

Bit Cipher 1. Example of bit Cipher 2 Practical Stream Cipher 3.

Brand-New Hash Function   BeeM A. Satoh SCIS2006 SHA-1 Broken! Prof. Xiaoyun Wang.

CSCI 172/283 Fall 2010 Hash Functions, HMACs, and Digital Signatures.

11.1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 11 Message Integrity and Message Authentication.

1 Network Security Lecture 5 Hashes and Message Digests Waleed Ejaz

Lecture 8 Overview. Secure Hash Algorithm (SHA) SHA SHA SHA – SHA-224, SHA-256, SHA-384, SHA-512 SHA-1 A message composed of b bits.

ECE Prof. John A. Copeland fax Office: GCATT Bldg.

Cryptographic Hash Functions and Protocol Analysis

CIT 380: Securing Computer SystemsSlide #1 CIT 380: Securing Computer Systems Modern Cryptography.

Chapter 11 Message Authentication and Hash Functions.

Cryptographic Hash Functions Prepared by Dr. Lamiaa Elshenawy

Cryptography and Network Security (CS435) Part Nine (Message Authentication)

Hash Functions Ramki Thurimella. 2 What is a hash function? Also known as message digest or fingerprint Compression: A function that maps arbitrarily.

CS426Fall 2010/Lecture 51 Computer Security CS 426 Lecture 5 Cryptography: Cryptographic Hash Function.

Hashes Lesson Introduction ●The birthday paradox and length of hash ●Secure hash function ●HMAC.

IT 221: Introduction to Information Security Principles Lecture 5: Message Authentications, Hash Functions and Hash/Mac Algorithms For Educational Purposes.

The Birthday Paradox July Definition 2 Birthday attacks are a class of brute-force techniques that target the cryptographic hash functions. The.

 Encryption provides confidentiality  Information is unreadable to anyone without knowledge of the key  Hashing provides integrity  Verify the integrity.

Cryptography Hyunsung Kim, PhD University of Malawi, Chancellor College Kyungil University February, 2016.

Cryptographic Hash Function. A hash function H accepts a variable-length block of data as input and produces a fixed-size hash value h = H(M). The principal.

Hashing (Message Digest) Hello There Hashing (Message Digest)

Cryptographic Hash Functions

Cryptographic Hash Function

CSCE 715: Network Systems Security

Introduction to security goals and usage of cryptographic algorithms

Cryptographic Hash Functions

Cryptography and Network Security Chapter 11

ICS 454 Principles of Cryptography

Cryptography and Network Security Chapter 11

<ELLIIT Project Name>

ICS 454 Principles of Cryptography

Poster Title Heading Heading Heading Heading Heading Heading

Chapter -7 CRYPTOGRAPHIC HASH FUNCTIONS

Hashing Hash are the auxiliary values that are used in cryptography.

目录 The quick brown fox. 目录 The quick brown fox.

Hash Function Requirements

Presentation transcript:

Hashing (Message Digest)

Hello There

Hashing (Message Digest) What not

Hash Function – One way Needed properties for cryptographically secure hash: 1. Computationally infeasible to find the message that has given the hash 2. Should be impossible for two messages to hash to the same number (and to find two messages with the same hash). Message substitution possible otherwise

Hash Function – One way Appearrance to a cracker: 1. Looking at output, any bit should be 1 about ½ the time Each output should have about ½ of its bits set to 1 3. Any two outputs should be uncorrelated no matter how similar the inputs are

Hash Function – One way Birthday Problem: Assume a completely random hash function If the number of output bits is k, then 2 k outputs possible Hash needs to map to (2 k )*(2 k ) values to get probability that two outputs are the same below ½.

Hashing (Message Digest) Secret The little brown fox jumped over the lazy dog's back

Hashing (Message Digest) The little brown fox jumped over the lazy dog's back

Hashing (Message Digest) The little brown fox jumped over the lazy dog's back

Hashing (Message Digest) The little brown fox jumped over the lazy dog's back

Hashing (Message Digest) The little brown fox jumped over the lazy dog's back

Hashing (Message Digest) The little brown fox jumped over the lazy dog's back

Hashing (Message Digest) The little brown fox jumped over the lazy dog's back Output

Hashing - authentication S S Client Monitor

Hashing - authentication S S Client Monitor Challenge R

Hashing - authentication S S Client Monitor Hash(S | R)

Hashing - authentication S S Client Monitor Check Hash(S | R)?

Hashing - authentication S S Client Monitor Challenge P

Hashing - authentication S S Client Monitor Hash(S | P)

Hashing - authentication S S Client Monitor Check Hash(S | P)?

Hashing - Message Authenication Same as authentication except concatenate the message with the secret and pad.

Hashing - Message Authenication Same as authentication except concatenate the message with the secret and pad. Unfortunately, attacker can append a message since s/he knows Hash(S | M) and the Hash algorithm.

Hashing - Message Authenication Same as authentication except concatenate the message with the secret and pad. Unfortunately, attacker can append a message since s/he knows Hash(S | M) and the Hash algorithm. Here is what to do: 1. Concatenate secret to front of message 2. Take the hash 3. Concatenate the secret to the front of the hash 4. Take the hash

Hashing - encryption Secret The little brown fox jumped over the lazy dog's back Initialization Vector + To receiver

Hashing - encryption Secret The little brown fox jumped over the lazy dog's back +

Hashing - encryption Secret The little brown fox jumped over the lazy dog's back + To receiver

Hashing - encryption Secret The little brown fox jumped over the lazy dog's back +

Hashing - encryption Secret The little brown fox jumped over the lazy dog's back + To receiver