If the hash algorithm is properly designed and distributes the hashes uniformly over the output space, "finding a hash collision" by random guessing is.

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 7 Overview. Advanced Encryption Standard 10, 12, 14 rounds for 128, 192, 256 bit keys – Regular Rounds (9, 11, 13) – Final Round is different.

By: Matthew Ng. AND, XOR, OR, Complement, Circular Left shift, and Addition Modulo Circular Left Shift is done with s positions (0 ≤ s ≤ 31) – Denoted.

MD Collision Sought Marian Ščerbák University of Pavol Jozef Šafárik Košice.

Tiger: a fast hash Eric Seidel CS 257: Security Engineering.

 Stream ciphers o Encrypt chars/bits one at a time o Assume XOR w the key, need long key to be secure  Keystream generators (pseudo-random key) o Synchronous.

PIITMadhumita Chatterjee Security 1 Hashes and Message Digests.

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

Announcements: 1. HW7 due next Tuesday. 2. Inauguration today! Questions? This week: Discrete Logs, Diffie-Hellman, ElGamal Discrete Logs, Diffie-Hellman,

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.

Announcements:Questions? This week: Discrete Logs, Diffie-Hellman, ElGamal Discrete Logs, Diffie-Hellman, ElGamal Hash Functions and SHA-1 Hash Functions.

MD5 Message Digest Algorithm CS265 Spring 2003 Jerry Li Computer Science Department San Jose State University.

Hashes and Message Digest Hash is also called message digest One-way function: d=h(m) but no h’(d)=m –Cannot find the message given a digest Cannot find.

By: Matthew Ng. SHA stands for Secure Hash Algorithm It is based off the Merkle-Dangard hash function There are 3 versions of it with one coming in 2012.

SHA (secure hash algorithm) Jen-Chang Liu, 2005 Adapted from lecture slides by Lawrie Brown.

Module 4 Hash Functions Highline Community College Seattle University University of Washington in conjunction with the National Science Foundation.

Cryptography and Network Security Third Edition by William Stallings Lecture slides by Lawrie Brown.

Lecture 13 Message Signing

Cryptography and Network Security Third Edition by William Stallings Lecture slides by Lawrie Brown.

1 Cryptography and Network Security (Various Hash Algorithms) Fourth Edition by William Stallings Lecture slides by Lawrie Brown (Changed by Somesh Jha)

Team Grey Skies – Pete Biancaniello and Anton Schraut January 18 th, 2012.

Lecture 15 Lecture’s outline Public algorithms (usually) that are each other’s inverse.

Hash and MAC Algorithms Dr. Monther Aldwairi New York Institute of Technology- Amman Campus 12/3/2009 INCS 741: Cryptography 12/3/20091Dr. Monther Aldwairi.

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

Lecture 4.1: Hash Functions, and Message Authentication Codes CS 436/636/736 Spring 2015 Nitesh Saxena.

Hashing Algorithms: Basic Concepts and SHA-2 CSCI 5857: Encoding and Encryption.

Data & Network Security

Hash and MAC Functions CS427 – Computer Security

Improving Encryption Algorithms Betty Huang Computer Systems Lab

“Implementation of a RC5 block cipher algorithm and implementing an attack on it” Cryptography Team Presentation 1.

1 Hash Functions. 2 A hash function h takes as input a message of arbitrary length and produces as output a message digest of fixed length

1 Network Security Lecture 5 Hashes and Message Digests Waleed Ejaz

If the hash algorithm is properly designed and distributes the hashes uniformly over the output space, "finding a hash collision" by random guessing is.

AES Advanced Encryption Standard. Requirements for AES AES had to be a private key algorithm. It had to use a shared secret key. It had to support the.

Chapter 18: One-Way Hash Functions Based on Schneier.

Hash Algorithms see similarities in the evolution of hash functions & block ciphers –increasing power of brute-force attacks –leading to evolution in algorithms.

Understanding Cryptography – A Textbook for Students and Practitioners by Christof Paar and Jan Pelzl Chapter 11 – Hash Functions.

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

1 Chapter 12: Hash and MAC Algorithms Fourth Edition by William Stallings Lecture slides by Lawrie Brown (modified by Prof. M. Singhal, U of Kentucky)

Computer Science CSC 474Dr. Peng Ning1 CSC 474 Information Systems Security Topic 2.3 Hash Functions.

Information Security and Management 11. Cryptographic Hash Functions Chih-Hung Wang Fall

Hash Algorithms Ch 12 of Cryptography and Network Security - Third Edition by William Stallings Modified from lecture slides by Lawrie Brown CIM3681 :

Cryptography and Network Security Third Edition by William Stallings Lecture slides by Lawrie Brown.

1 Message Authentication using Message Digests and the MD5 Algorithm Message authentication is important where undetected manipulation of messages can.

CS480 Cryptography and Information Security Huiping Guo Department of Computer Science California State University, Los Angeles 13.Message Authentication.

Data Integrity / Data Authentication. Definition Authentication (Signature) algorithm - A Verification algorithm - V Authentication key – k Verification.

Chapter 12 – Hash Algorithms

Secure Hash Algorithm A SEARIES OF SHA….

If the hash algorithm is properly designed and distributes the hashes uniformly over the output space, "finding a hash collision" by random guessing is.

If the hash algorithm is properly designed and distributes the hashes uniformly over the output space, "finding a hash collision" by random guessing is.

MD5 A Hash Algorithm….

Network Security Unit-III

Cryptography and Network Security (Various Hash Algorithms)

Simplified IDEA Cryptography and Network Security.

MD5 A Hash Algorithm….

کدهاي احراز تماميت پيام و توابع درهم ساز

Cryptography Lecture 19.

Unit 2 “Implementation of a RC5 block cipher algorithm and implementing an attack on it”

Hash and MAC Algorithms

Lecture 4.1: Hash Functions: Introduction

SYMMETRIC ENCRYPTION.

Lecture 4.1: Hash Functions, and Message Authentication Codes

Cryptography Lecture 13.

Cryptographic Hash Functions

Cryptography Lecture 18.

Lecture 4: Hash Functions

The Secure Hash Function (SHA)

Data Encryption Standard (DES)

Simple Hash Functions Network Security.

Presentation transcript:

If the hash algorithm is properly designed and distributes the hashes uniformly over the output space, "finding a hash collision" by random guessing is exceedingly unlikely (it's more likely that a million people will correctly guess all the California Lottery numbers every day for a billion trillion years). This astonishing fact is due to the astonishingly large number of possible hashes available: a 128-bit hash can have 3.4 x 10^38 possible values, which is: 340,282,366,920,938,463,463,374,607,431,768,211,456 possible hashes

atoms in the universe = 1078 to just under 1081 = 1 gig numbers / sec 1 gig = 10^9 = 2^30 128 bit will take 2^98 secs = 2^73 years = 10^20 years 100,000,000,000,000,000,000 years (1 year = 2^25 secs) atoms in the universe = 1078 to just under 1081 = i.e. 2246 to 2256

Merkle Damgard Compression e.g. MD-5 uses 512 blocks of messages per round of compression, each broken into 4 stages (128 bits)

One MD5 operation. MD5 consists of 64 of these operations, grouped in four rounds of 16 operations. (A,B etc = 32 bits) F is a nonlinear function; one function is used in each round. Mi denotes a 32-bit block of the message input, and Ki denotes a 32-bit constant, different for each operation. <<<s denotes a left bit rotation by s places; s varies for each operation. + denotes addition modulo 232.

Hash collisions Thought to be impossible Only one known so far for a “good” algorithm MD5 hash collision

SHA-1: 160 bit hash Start with 512 bit blocks of input, pad it if needed. Expand to 80 32-bit subkeys (Wt) Initialize some hash blocks (A, B, …E) Use input to generate Wt, Kt is a constant. F is a changeable functions, constructed from shifts, and XORs. Do 80 rounds. Then use more input. Can be made to be fast.