Search results “Preimage resistance in cryptography research”

Talk at crypto 2012. Authors: Simon Knellwolf, Dmitry Khovratovich. See http://www.iacr.org/cryptodb/data/paper.php?pubkey=24323

Views: 784
TheIACR

Cryptography constructing compression functions
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About this course: Cryptography is an indispensable tool for protecting information in computer systems. In this course you will learn the inner workings of cryptographic systems and how to correctly use them in real-world applications. The course begins with a detailed discussion of how two parties who have a shared secret key can communicate securely when a powerful adversary eavesdrops and tampers with traffic. We will examine many deployed protocols and analyze mistakes in existing systems. The second half of the course discusses public-key techniques that let two parties generate a shared secret key.

Views: 141
intrigano

Cryptography and Network Security by Prof. D. Mukhopadhyay, Department of Computer Science and Engineering, IIT Kharagpur. For more details on NPTEL visit http://nptel.iitm.ac.in

Views: 12045
nptelhrd

Why should we be concerned about the successful SHA-1 collision attack that was recently demonstrated by Google researchers?
I take a look at encryption, cryptographic hashing, and why this attack is a big deal.
Read the post here. https://security.googleblog.com/2017/02/announcing-first-sha1-collision.html

Views: 896
J4vv4D

We show that preimages of SHA-1 can be computed at the cost of 2^159.3 compression function computations. For variants with a reduced number of steps we obtain significantly faster attacks than previously known. The best previous attack was on 48 (of 80) steps with a complexity of 2^159.3. Our attack on this variant has complexity 2^152.1. The new results heavily rely on the linear message expansion and the low diffusion of the step transformation. The techniques in this paper apply to any hash function with linear message expansion. In the talk we will provide a general introduction to meet-in-the-middle preimage attacks on hash functions.

Views: 221
Microsoft Research

Jian Guo, Thomas Peyrin, and Axel Poschmann
Institute for Infocomm Research, Singapore; Nanyang Technological University, Singapore; and Nanyang Technological University, Singapore
Abstract. RFID security is currently one of the major challenges cryptography has to face, often solved by protocols assuming that an ontag hash function is available. In this article we present the PHOTON lightweight hash-function family, available in many dierent avors and suitable for extremely constrained devices such as passive RFID tags. Our proposal uses a sponge-like construction as domain extension algorithm and an AES-like primitive as internal unkeyed permutation. This allows us to obtain the most compact hash function known so far (about 1120 GE for 64-bit collision resistance security), reaching areas very close to the theoretical optimum (derived from the minimal internal state memory size). Moreover, the speed achieved by PHOTON also compares quite favorably to its competitors. This is mostly due to the fact that unlike for previously proposed schemes, our proposal is very simple to analyze and one can derive tight AES-like bounds on the number of active Sboxes. This kind of AES-like primitive is usually not well suited for ultra constrained environments, but we describe in this paper a new method for generating the column mixing layer in a serial way, lowering drastically the area required. Finally, we slightly extend the sponge framework in order to oer interesting trade-os between speed and preimage security for small messages, the classical use-case in hardware.

Views: 1141
TheIACR

Marc Stevens and Pierre Karpman and Thomas Peyrin, presented at Eurocrypt 2016. See http://www.iacr.org/cryptodb/data/paper.php?pubkey=27631

Views: 320
TheIACR

Researchers from Google, the Cryptology Group at Centrum Wiskunde and Informatica in Amsterdam, published a paper last week about the first practical collision attack for the cryptographic hash function SHA-1. The attack method entails the collision of two PDF files by obtaining the SHA-1 signature on the first PDF and mimicking the signature to exploit the second PDF. The attack utilized Google’s cloud infrastructure and used nine quintillion SHA-1 computations in total, making it among the largest computations ever completed. The first phase of the attack was carried out over 8 separate locations, and the second on a single cluster of GPUs hosted by Google.
SHA-1 is a 22 year old function and has had theoretical attacks conceptualized since 2005. This attack, carried out by these researchers, took 2 years to execute.
https://shattered.it/static/shattered.pdf
https://threatpost.com/first-practical-sha-1-collision-attack-arrives/123868/
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Twitter: @CyberTrain365

Views: 109
CyberTraining 365

MIT 6.858 Computer Systems Security, Fall 2014
View the complete course: http://ocw.mit.edu/6-858F14
Instructor: James Mickens
In this lecture, Professor Mickens discusses authentication schemes and their implementations.
License: Creative Commons BY-NC-SA
More information at http://ocw.mit.edu/terms
More courses at http://ocw.mit.edu

Views: 6928
MIT OpenCourseWare

The MD5 message-digest algorithm is a widely used cryptographic hash function producing a 128-bit (16-byte) hash value, typically expressed in text format as a 32 digit hexadecimal number. MD5 has been utilized in a wide variety of cryptographic applications, and is also commonly used to verify data integrity.
MD5 was designed by Ron Rivest in 1991 to replace an earlier hash function, MD4. The source code in RFC 1321 contains a "by attribution" RSA license.
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Views: 4144
Audiopedia

http://2017.jsconf.eu/speakers/emil-bay-keeping-passwords-safe-in-2017.html
Every other week there seems to be a new dump of cracked passwords, hurting innocent and unbeknownst users. It seems as if keeping users passwords safe is an herculean task, even beyond the most resourceful organisations. However it doesn’t have to be.
Password hashing is a important discipline in cryptography. Securing passwords has become so integral to our society that in 2013 a Password Hashing Competition was announced, for the academic community to band together and develop a common recommendation for future use. In this talk I’ll showcase how to handle passwords correctly and safely and clear out misinformation that is still abound in tutorials and blog posts. All with heaps of demos to motivate, make the material concrete and so everyone can follow along!

Views: 7417
JSConf

On the first day of 2016, Mozilla terminated support for a weakening security technology called SHA-1 in the Firefox web browser. Almost immediately, they reversed their decision, as it would cut access to some older websites. But in February 2017, their fears finally came true: researchers broke SHA-1 by creating the first real-world collision attack. Here’s what all that means. What Is SHAttered? SHA-1 Collision Attacks, Explained
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Views: 55
Taoufiq Ait Ali

Talk at crypto 2012. Author: Jonathan Zittrain. See http://www.iacr.org/cryptodb/data/paper.php?pubkey=24329

Views: 9606
TheIACR

The MD5 message-digest algorithm is a widely used cryptographic hash function producing a 128-bit hash value, typically expressed in text format as a 32 digit hexadecimal number. MD5 has been utilized in a wide variety of cryptographic applications, and is also commonly used to verify data integrity.
This video targeted to blind users.
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Article text available under CC-BY-SA
Creative Commons image source in video

Views: 23638
encyclopediacc

Talk at crypto 2012. Authors: Joël Alwen, Jonathan Katz, Ueli Maurer, Vassilis Zikas. See http://www.iacr.org/cryptodb/data/paper.php?pubkey=24309

Views: 244
TheIACR

SHA-2 is a set of cryptographic hash functions (SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, SHA-512/256) designed by the U.S. National Security Agency (NSA) and published in 2001 by the NIST as a U.S. Federal Information Processing Standard (FIPS). Cryptographic hash functions are a kind of algorithm or mathematical operation run on digital data, and by comparing the result of the "hash" (the execution of the algorithm) to a known and expected hash value, a person can determine the data's authenticity. An example is running a hash on downloaded software and comparing the result to the developer's published hash result, to see if the software is genuine, and safe to run. An added benefit of cryptographic hash functions is they are almost impossible to reverse engineer to reconstruct the original data.
SHA stands for Secure Hash Algorithm. SHA-2 includes a significant number of changes from its predecessor, SHA-1. SHA-2 currently consists of a set of six hash functions with digests (hash values) that are 224, 256, 384 or 512 bits.
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Views: 4672
Audiopedia

Talk at crypto 2012. Authors: Will Landecker, Thomas Shrimpton, R. Seth Terashima. See http://www.iacr.org/cryptodb/data/paper.php?pubkey=24326

Views: 313
TheIACR

Talk at crypto 2012. Authors: Mihir Bellare, Thomas Ristenpart, Stefano Tessaro. See http://www.iacr.org/cryptodb/data/paper.php?pubkey=24316

Views: 344
TheIACR

In cryptography, SHA-1 is a cryptographic hash function designed by the United States National Security Agency and is a U.S. Federal Information Processing Standard published by the United States NIST.
SHA-1 produces a 160-bit (20-byte) hash value. A SHA-1 hash value is typically rendered as a hexadecimal number, 40 digits long.
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Views: 1017
Audiopedia

In computer science, a one-way function is a function that is easy to compute on every input, but hard to invert given the image of a random input. Here, "easy" and "hard" are to be understood in the sense of computational complexity theory, specifically the theory of polynomial time problems. Not being one-to-one is not considered sufficient of a function for it to be called one-way.
The existence of such one-way functions is still an open conjecture. In fact, their existence would prove that the complexity classes P and NP are not equal, thus resolving the foremost unsolved question of theoretical computer science. The converse is not known to be true, i.e. the existence of a proof that P and NP are not equal would not directly imply the existence of one-way functions.
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Views: 519
Audiopedia

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