Views: 40532 Lisk
MIT 6.046J Design and Analysis of Algorithms, Spring 2015 View the complete course: http://ocw.mit.edu/6-046JS15 Instructor: Srinivas Devadas In this lecture, Professor Devadas covers the basics of cryptography, including desirable properties of cryptographic functions, and their applications to security. License: Creative Commons BY-NC-SA More information at http://ocw.mit.edu/terms More courses at http://ocw.mit.edu
Views: 76208 MIT OpenCourseWare
Audible free book: http://www.audible.com/computerphile Hashing Algorithms are used to ensure file authenticity, but how secure are they and why do they keep changing? Tom Scott hashes it out. More from Tom Scott: http://www.youtube.com/user/enyay and https://twitter.com/tomscott http://www.facebook.com/computerphile https://twitter.com/computer_phile This video was filmed and edited by Sean Riley. Pigeon Sound Effects courtesy of http://www.freesfx.co.uk/ Computerphile is a sister project to Brady Haran's Numberphile. See the full list of Brady's video projects at: http://bit.ly/bradychannels
Views: 788246 Computerphile
Modern cryptography depends on the existence of several special kinds of mathematical functions. One important kind is a trapdoor function. Trapdoor functions are somewhat similar to hash functions in that they are easy to compute but hard to invert… except if you know a secret piece of information. So if someone does not have the secret or key, they cannot invert the function. If they do, they can open the trapdoor and invert the function. Trapdoor functions form the basis of modern cryptographic techniques that are widely-used online. Credits: Talking: Geoffrey Challen (Assistant Professor, Computer Science and Engineering, University at Buffalo). Producing: Greg Bunyea (Undergraduate, Computer Science and Engineering, University at Buffalo). Part of the https://www.internet-class.org online internet course. A blue Systems Research Group (https://blue.cse.buffalo.edu) production.
Views: 9156 internet-class
Hashing Techniques Hash Function, Types of Hashing Techniques in Hindi and English * Direct Hashing * Modulo-Division Hashing * Mid-Square Hashing * Folding Hashing - Fold-Shift Hashing and Fold Boundary Hashing * PseudoRandom Hashing * Subtraction Hashing For Students of B.Tech, B.E, MCA, BCA, B.Sc., M.Sc., Courses - As Per IP University Syllabus and Other Engineering Courses
Views: 267864 Easy Engineering Classes
Applying the pigeonhole principle to (cryptographic) hash functions to determine how many inputs collide on a single hash value.
Views: 1405 Steven Gordon
This video gives a motivation and a general idea about the concept of "One-Way Function" in Cryptography. The concept of function is defined and some examples are given.
Views: 3002 Leandro Junes
What is Hashing & Digital Signature in The Blockchain? https://blockgeeks.com/ Today, we're going to be talking about the word blockchain and breaking it down to understand what does it mean when someone says, "Blockchain." What is hashing? Hashing refers to the concept of taking an arbitrary amount of input data, applying some algorithm to it, and generating a fixed-size output data called the hash. The input can be any number of bits that could represent a single character, an MP3 file, an entire novel, a spreadsheet of your banking history, or even the entire Internet. The point is that the input can be infinitely big. The hashing algorithm [00:01:00] can be chosen depending on your needs and there are many publicly available hashing algorithms. The point is that the algorithm takes the infinite input of bits, applies some calculations to them, and outputs a finite number of bits. For example, 256 bits. What can this hash be used for? A common usage for hashes today is to fingerprint files, also known as check zones. This means that a hash is used to verify that a file has not been [00:01:30] tampered with or modified in any way not intended by the author. If WikiLeaks, for example, publishes a set of files along with their MD5 hashes, whoever downloads those files can verify that they are actually from WikiLeaks by calculating the MD5 hash of the downloaded files, and if the hash doesn't match what was published by WikiLeaks, then you know that the file has been modified in some way. How does the blockchain make use of hashes? [00:02:00] Hashes are used in blockchains to represent the current state of the world. The input is the entire state of the blockchain, meaning all the transactions that have taken place so far and the resulting output hash represents the current state of the blockchain. The hash is used to agree between all parties that the world state is one in the same, but how are these hashes actually calculated? The first hash is calculated for the first block [00:02:30] or the Genesis block using the transactions inside that block. The sequence of initial transactions is used to calculate a block hash for the Genesis block. For every new block that is generated afterwords, the previous block's hash is also used, as well as its own transactions, as input to determine its block hash. This is how a chain of blocks is formed, each new block hash pointing to the block hash that came before it. This system of hashing guarantees that no transaction in the history can be tampered with because if any single part of the transaction changes, so does the hash of the block to which it belongs, and any following blocks' hashes as a result. It would be fairly easy to catch any tampering as a result because you can just compare the hashes. This is cool because everyone on the blockchain only needs to agree on 256 bits to represent the potentially infinite state of the blockchain. The Ethereum blockchain is currently tens of gigabytes, but the current state of the blockchain, as of this recording, is this hexadecimal hash representing 256 bits. What about digital signatures? Digital signatures, like real signatures, are a way to prove that somebody is who they say they are, except that we use cryptography or math, which is more secure than handwritten signatures that can be [00:04:00] easily forged. A digital signature is a way to prove that a message originates from a specific person and no one else, like a hacker. Digital signatures are used today all over the Internet. Whenever you visit a website over ACTPS, you are using SSL, which uses digital signatures to establish trust between you and the server. This means that when you visit Facebook.com, your browser can check the digital signature that came with the web page to verify that it indeed originated from Facebook and not some hacker. In asymmetric encryption systems, users generate something called a key pair, which is a public key and a private key using some known algorithm. The public key and private key are associated with each other through some mathematical relationship. The public key is meant to be distributed publicly to serve as an address to receive messages from other users, like an IP address or home address. The private key is meant to be kept secret and is used to digitally sign messages sent to other users. The signature is included with the message so that the recipient can verify using the sender's public key. This way, the recipient can be sure that only the sender could have sent this message. Generating a key pair is analogous to creating an account on the blockchain, but without having to actually register anywhere. Pretty cool. Also, every transaction that is executed on the blockchain is digitally signed by the sender using their private key. This signature ensures that only the owner of the account can move money out of the account.
Views: 26929 Blockgeeks
A review of hashing algorithms, including MD5. Hash collisions. Plus: cracking passwords!
Views: 1121 Barry Brown
The definition of a one-way function is given in this video. Several examples of one-way functions are given.
Views: 756 Leandro Junes
This video discusses 1-1 functions, surjective functions, and bijective functions. Several examples are given. These concepts are given in preparation for the definition of "One-Way Function"
Views: 907 Leandro Junes
Cryptography constructing compression functions To get certificate subscribe: https://www.coursera.org/learn/crypto ======================== Playlist URL: https://www.youtube.com/playlist?list=PL2jykFOD1AWYosqucluZghEVjUkopdD1e ======================== 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: 266 intrigano
A cryptographic hash function is a hash function which is considered practically impossible to invert, that is, to recreate the input data from its hash value alone. The input data is often called the message, and the hash value is often called the message digest or simply the digest. This video is targeted to blind users. Attribution: Article text available under CC-BY-SA Creative Commons image source in video
Views: 2401 Audiopedia
Other units in this course below: Unit 1: http://www.youtube.com/playlist?list=PLF6D042E98ED5C691 Unit 2: http://www.youtube.com/playlist?list=PL6A1005157875332F Unit 3: http://www.youtube.com/playlist?list=PL62AE4EA617CF97D7 Unit 4: http://www.youtube.com/playlist?list=PL886F98D98288A232 Unit 5: http://www.youtube.com/playlist?list=PLBA8DEB5640ECBBDD Unit 6: http://www.youtube.com/playlist?list=PL6B5C5EC17F3404D6 Unit 7: http://www.youtube.com/playlist?list=PL6511E7098EC577BE Q&A: http://www.youtube.com/playlist?list=PLDA5F9F71AFF4B69E To gain access to interactive quizzes, homework, programming assignments and a helpful community, join the class at http://www.udacity.com
Views: 34274 Udacity
A hash function is any function that can be used to map data of arbitrary size to data of fixed size, with slight differences in input data producing very big differences in output data. The values returned by a hash function are called hash values, hash codes, hash sums, or simply hashes. One practical use is a data structure called a hash table. Hash functions are also frequently used to accelerate table or database lookup, detecting duplicated records in a large file, and finding similar stretches in DNA sequences. They are also useful in cryptography. A cryptographic hash function allows one to easily verify that some input data matches a stored hash value, but hard to reconstruct the data from the hash alone. This principle is used by the PGP algorithm for data validation and by many password checking systems. Hash functions are related to (and often confused with) checksums, check digits, fingerprints, randomization functions, error-correcting codes, and ciphers. Although these concepts overlap to some extent, each has its own uses and requirements and is designed and optimized differently. The Hash Keeper database maintained by the American National Drug Intelligence Center, for instance, is more aptly described as a catalog of file fingerprints than of hash values. This video is targeted to blind users. Attribution: Article text available under CC-BY-SA Creative Commons image source in video
Views: 518 Audiopedia
#ask faizan | #syedfaizanahmad | #hashfunctions Types of Message Authentication | MAC | Part 2 | Network Security | Hindi Urdu https://youtu.be/C88ujAT8N0U Types of Message Authentication | Message Encryption | Part 1 | Network Security | Hindi Urdu https://youtu.be/2eRGEntqpL4 DIFFIE HELLMAN KEY EXCHANGE ALGORITHM | Diffie-Hellman key exchange algorithm | HINDI URDU https://youtu.be/I6oUvYzPMXc RSA Algorithm | RSA Algorithm Concept | RSA Algorithm with Example | Hindi / Urdu https://youtu.be/s3CH9c3Jcu0 How to find Euler's Totient Function https://youtu.be/6wHwTB-bRlw DES | Simple Explanation | Data Encryption Standard Algo https://youtu.be/oR1JQJlXtq4 Network Security - Transposition Techniques https://youtu.be/h4MOqFkN9Tk Block Cipher Modes of Operation | CTR mode https://youtu.be/Rp5HOTe4EbE Block Cipher Modes of Operation | OFB mode https://youtu.be/F2RwmXwrdV8 Block Cipher Modes of Operation | CFB mode https://youtu.be/yF_iA7Rv7k4 Block Cipher Modes of Operation | CBC mode | Part 2 https://youtu.be/Q7LKmASkVSU Block Cipher Modes of Operation | ECB mode | Part 1 https://youtu.be/mkY5mNSnuko Hill Cipher | Complete Algorithm with Example https://youtu.be/B0Q7w7Fd7ms Playfair Substitution Cipher https://youtu.be/w_xr7pj-O6c Monoalphabetic Substitution Cipher https://youtu.be/Hw1T7GOnVW0 Caesar Cipher | Caesar Substitution Cipher https://youtu.be/2N9GlhysYJw PlayList : Cryptography and Network Security : https://www.youtube.com/playlist?list=PLhwpdymnbXz7hvvqhqjIIG4tEdhAgQqll Types of Message Authentication | Hash Function | Part 3 | Network Security | Hindi Urdu
Views: 415 Ask Faizan
Supplement to the cryptocurrency video: How hard is it to find a 256-bit hash just by guessing and checking? What kind of computer would that take? Cryptocurrency video: https://youtu.be/bBC-nXj3Ng4 Home page: https://www.3blue1brown.com/ Several people have commented about how 2^256 would be the maximum number of attempts, not the average. This depends on the thing being attempted. If it's guessing a private key, you are correct, but for something like guessing which input to a hash function gives the desired output (as in bitcoin mining, for example), which is the kind of thing I had in mind here, 2^256 would indeed be the average number of attempts needed, at least for a true cryptographic hash function. Think of rolling a die until you get a 6, how many rolls do you need to make, on average? Music by Vince Rubinetti: https://vincerubinetti.bandcamp.com/album/the-music-of-3blue1brown ------------------ 3blue1brown is a channel about animating math, in all senses of the word animate. And you know the drill with YouTube, if you want to stay posted on new videos, subscribe, and click the bell to receive notifications (if you're into that). If you are new to this channel and want to see more, a good place to start is this playlist: http://3b1b.co/recommended Various social media stuffs: Website: https://www.3blue1brown.com Twitter: https://twitter.com/3Blue1Brown Patreon: https://patreon.com/3blue1brown Facebook: https://www.facebook.com/3blue1brown Reddit: https://www.reddit.com/r/3Blue1Brown
Views: 1059024 3Blue1Brown
This video lecture is produced by S. Saurabh. He is B.Tech from IIT and MS from USA. hashing in data structure hash table hash function hashing in dbms To study interview questions on Linked List watch http://www.youtube.com/playlist?list=PL3D11462114F778D7&feature=view_all To prepare for programming Interview Questions on Binary Trees http://www.youtube.com/playlist?list=PLC3855D81E15BC990&feature=view_all To study programming Interview questions on Stack, Queues, Arrays visit http://www.youtube.com/playlist?list=PL65BCEDD6788C3F27&feature=view_all To watch all Programming Interview Questions visit http://www.youtube.com/playlist?list=PLD629C50E1A85BF84&feature=view_all To learn about Pointers in C visit http://www.youtube.com/playlist?list=PLC68607ACFA43C084&feature=view_all To learn C programming from IITian S.Saurabh visit http://www.youtube.com/playlist?list=PL3C47C530C457BACD&feature=view_all
Views: 331426 saurabhschool
This video is part of an online course, Applied Cryptography. Check out the course here: https://www.udacity.com/course/cs387.
Views: 6606 Udacity
This is a discussion video on the birthday attack, the birthday paradox and the maths around the attack using MD5. All Links and Slides will be in the description. Subscribe for more cool stuff! Slides & files - http://www.mediafire.com/view/vdbpbrabj6j50x2/BirthdayAttack.pptx Python - http://python.org/ Ubuntu - http://www.ubuntu.com/ If you like what you see be sure to subscribe and thumbs up!
Views: 30914 DrapsTV
Link to My Blog:- http://techdjdey.blogspot.in/ Video Editor used:- HitFilm 4 Express. https://hitfilm.com/ Screen recorder used:- iSpring Free Cam 8. https://www.ispringsolutions.com/ispring-free-cam Music:- Elektronomia-Sky High. https://www.youtube.com/watch?v=TW9d8vYrVFQ PLEASE LIKE AND SHARE THIS VIDEO. SUBSCRIBE to my Channel here:- https://www.youtube.com/channel/UCFKcqq9IOdwHdgfq6GEL8gw?sub_confirmation=1 My other videos:- https://www.youtube.com/channel/UCFKcqq9IOdwHdgfq6GEL8gw/videos IGNORE THESE BELOW: 1. what is the difference between steganography and cryptography c cryptography c cryptography example c cryptography library c cryptography tutorial cryptographic protocol e cryptography f# cryptography lightweight cryptography nonlinear cryptography o cryptography r cryptography what does cryptography have to do with math what does cryptography look like today what is a certificate in cryptography what is a cipher in cryptography what is a crib in cryptography what is a generator cryptography what is a hash cryptography what is a nonce in cryptography what is a public key cryptography what is a quantum cryptography what is a seed in cryptography what is a symmetric cryptography what is advantages of cryptography what is asymmetric key cryptography what is biometric cryptography what is bitcoin cryptography what is broken cryptography what is cbc cryptography what is chaos cryptography what is chaotic cryptography what is cipher cryptography what is classical cryptography what is cloud cryptography what is confusion and diffusion in cryptography with example what is conventional cryptography what is cryptographic hash function what is cryptographic hash functions examples what is cryptography what is cryptography algorithm what is cryptography and cryptanalysis what is cryptography and encryption what is cryptography and history what is cryptography and how is it used what is cryptography and how is it used in it security what is cryptography and its importance what is cryptography and its types what is cryptography and network security what is cryptography and network security ppt what is cryptography and network security wikipedia what is cryptography and number theory what is cryptography and steganography what is cryptography and theoretical informatics what is cryptography and why is it important what is cryptography and why is it used what is cryptography basics what is cryptography computer what is cryptography define the process of encryption and decryption what is cryptography definition what is cryptography doc what is cryptography encryption what is cryptography engineering what is cryptography error what is cryptography explain what is cryptography explain in detail what is cryptography explain its types what is cryptography hashing what is cryptography how is it used in it security what is cryptography in .net what is cryptography in c# what is cryptography in computer what is cryptography in computer network what is cryptography in computer security what is cryptography in cyber security what is cryptography in hindi what is cryptography in information security what is cryptography in java what is cryptography in mathematics what is cryptography in network security what is cryptography in networking what is cryptography in operating system what is cryptography in os what is cryptography in registry what is cryptography in security what is cryptography in simple language what is cryptography in web security what is cryptography key what is cryptography key management what is cryptography law what is cryptography library what is cryptography method what is cryptography module what is cryptography network security what is cryptography next generation what is cryptography pdf what is cryptography ppt what is cryptography provide an example what is cryptography quora what is cryptography rng seed what is cryptography salary what is cryptography salt what is cryptography service what is cryptography slideshare what is cryptography software what is cryptography system what is cryptography teach ict what is cryptography technique what is cryptography technology what is cryptography tools what is cryptography tutorial point what is cryptography types what is cryptography used for what is cryptography used for today what is cryptography video what is cryptography virus what is cryptography wikipedia what is cryptography with diagram what is cryptography with example what is cryptography yahoo what is cryptography yahoo answers what is cryptography youtube what is data cryptography what is des cryptography what is difference between cryptography and encryption what is difference between cryptography and steganography what is diffusion cryptography what is digital cryptography what is discrete logarithm in cryptography what is distributed cryptography what is dna cryptography what is dsa cryptography what is ecc cryptography what is elementary cryptography
Views: 2489 Dhrubajyoti Dey
This Tutorial Explain What is Digital Signature in Hindi. A Digital Signature in Hindi (not to be confused with a digital certificate) is a mathematical technique used to validate the authenticity and integrity of a message, software or digital document. It Covers Points like digital signature in cryptography in hindi, digital signature in network security and digital signature in dbms(advance database management system) Digital Signature Use Asymatric Key to Encrypt Data. Digital signatures are often used to implement electronic signatures, a broader term that refers to any electronic data that carries the intent of a signature How digital signatures work Digital signatures are based on public key cryptography, also known as asymmetric cryptography. Using a public key algorithm such as RSA, one can generate two keys that are mathematically linked: one private and one public. To create a digital signature, signing software (such as an email program) creates a one-way hash of the electronic data to be signed. The private key is then used to encrypt the hash. The encrypted hash -- along with other information, such as the hashing algorithm -- is the digital signature. The reason for encrypting the hash instead of the entire message or document is that a hash function can convert an arbitrary input into a fixed length value, which is usually much shorter. This saves time since hashing is much faster than signing. Subscribe my Channel: https://goo.gl/FYkHc5 Reference Link: https://en.wikipedia.org/wiki/Digital_signature
Views: 10023 Introtuts
#WhatareHashValues? Important Hash Value Algorithms MD5, SHA-1 and SHA 2 - A #HashValue also is known as #Hashes are #Checksum ( is a string value of Specific Length ) which is a result of calculation of #HashingAlgorithm. - Hash Values have different users, One of the uses of hash values is to determine the integrity of any data. - Most wonderful characters of hash values are that they are highly unique.No two data can theoretically have the same hash values. - A condition called as in hashing - A collision is a situation when two different data have the same hash value - Best hashing algorithm is the one which cannot cause hash value collision. Important hashing algorithm are listed below: MD5 - Message digest by, RFC 1321 - Invented by RSA Labs in1991 - To replace It's previous version MD4 - Generate a 128 Bit Hash Value has a 32 bit hexa desimal number SHA- 1 [ Secure Hash Algorithm -1, Defined by RFC 3174] - Invented by United States National Security in 1995 - Generate a 160 bit hash value string as a hexadecimal number SHA-2 [Secure Hash Algorithm 2] Designed to the national institute of Standards and Technology and the national security agency 2001 Family of Hash Algorithms with different block sizes Calles as SHA 256 and other is called as SHA 512 SHA 256 uses 32-bit words where SHA 512 uses 64-bit words Six types of SHA- 2 Algorithms: 1- SHA 256 2- SHA 512 3- SHA 224 4- SHA-512 by 224 SH-2 Has a much higher level of security than it's predecessor SHA-1 #networkbulls #simpleilearn #inetwork #imedita #netmetricsolutions #networkchamps #udemy #networkbulls #jetking #simpleilearn #networkings #ip4networkers #mohannetworkinginstitute #yet5 #NOAsolutionshyderabad #jagvinderthird #yurisayed #ITchamppx #inetraining #ryanbeney #pearsoncertifications #itplus #telugutecktuts #danscourses #asmeducationcenter #AndrewCrouthamel #ToddLammle #AnkitShukla #KeithBarker #kushalkabi #FIDELTECH #RouteHub #TrevorTraining #ifactnertechnical #KevinWallace #ZoomTechnologies #AnkitShukla #NetCertExpert #CiscoTrainingChannel #CRISPBhopal #ManojShakya #ProfessorMesser #AhmadNadeem #myitfriends #GlobalKnowledge #macglobal #certbros #ciscomeraki #cisconetworking #thenetworkingdoctors #moustaphafall #cscopr #danscourses #learningatcisco #networkshield #narayanbaghel #orahergun
Views: 175 NETWORKERS HOME
How do we exchange a secret key in the clear? Spoiler: We don't - Dr Mike Pound shows us exactly what happens. Mathematics bit: https://youtu.be/Yjrfm_oRO0w Computing Limit: https://youtu.be/jv2H9fp9dT8 https://www.facebook.com/computerphile https://twitter.com/computer_phile This video was filmed and edited by Sean Riley. Computer Science at the University of Nottingham: https://bit.ly/nottscomputer Computerphile is a sister project to Brady Haran's Numberphile. More at http://www.bradyharan.com
Views: 242684 Computerphile
Viewers like you help make PBS (Thank you 😃) . Support your local PBS Member Station here: https://to.pbs.org/donateinfi Only 4 steps stand between you and the secrets hidden behind RSA cryptography. Find out how to crack the world’s most commonly used form of encryption. Tweet at us! @pbsinfinite Facebook: facebook.com/pbsinfinite series Email us! pbsinfiniteseries [at] gmail [dot] com Previous Episode: Can We Combine pi & e into a Rational Number? https://www.youtube.com/watch?v=bG7cCXqcJag&t=25s Links to other resources: Shor's paper: https://arxiv.org/abs/quant-ph/9508027v2 Lecture on Shor's Algorithm: https://arxiv.org/pdf/quant-ph/0010034.pdf Blog on Shor's algorithm: http://www.scottaaronson.com/blog/?p=208 Video on RSA cryptography: https://www.youtube.com/watch?v=wXB-V_Keiu8 Another video on RSA cryptography: https://www.youtube.com/watch?v=4zahvcJ9glg Euler's Big Idea: https://en.wikipedia.org/wiki/Euler%27s_theorem (I can find a non-wiki article, but I don't actually use this in the video. It's just where to learn more about the relevant math Euler did.) Written and Hosted by Kelsey Houston-Edwards Produced by Rusty Ward Graphics by Ray Lux Made by Kornhaber Brown (www.kornhaberbrown.com) Challenge Winner - Reddles37 https://www.youtube.com/watch?v=bG7cCXqcJag&lc=z135cnmgxlbwch1ds233sbzgaojkivaz004 Comments answered by Kelsey: Joel David Hamkins https://www.youtube.com/watch?v=bG7cCXqcJag&lc=z13zdpcwyk2ofhugh04cdh4agsr2whmbsmk0k PCreeper394 https://www.youtube.com/watch?v=bG7cCXqcJag&lc=z135w324kw21j1qi104cdzvrpoixslmq1jw
Views: 195313 PBS Infinite Series
Views: 179 asha khilrani
RSA Public Key Encryption Algorithm (cryptography). How & why it works. Introduces Euler's Theorem, Euler's Phi function, prime factorization, modular exponentiation & time complexity. Link to factoring graph: http://www.khanacademy.org/labs/explorations/time-complexity
Views: 583075 Art of the Problem
Bitcoins are mined using a cryptographic algorithm called SHA-256. This algorithm is simple enough to be done with pencil and paper, as I show in this video. Not surprisingly, this is a thoroughly impractical way to mine. One round of the algorithm takes 16 minutes, 45 seconds which works out to a hash rate of 0.67 hashes per day. For details, see http://righto.com/sha
Views: 1195372 Ken Shirriff
What is RANDOM ORACLE? What does RANDOM ORACLE mean? RANDOM ORACLE meaning - RANDOM ORACLE definition - RANDOM ORACLE explanation. Source: Wikipedia.org article, adapted under https://creativecommons.org/licenses/by-sa/3.0/ license. SUBSCRIBE to our Google Earth flights channel - https://www.youtube.com/channel/UC6UuCPh7GrXznZi0Hz2YQnQ In cryptography, a random oracle is an oracle (a theoretical black box) that responds to every unique query with a (truly) random response chosen uniformly from its output domain. If a query is repeated it responds the same way every time that query is submitted. Stated differently, a random oracle is a mathematical function chosen uniformly at random, that is, a function mapping each possible query to a (fixed) random response from its output domain. Random oracles as a mathematical abstraction were firstly used in rigorous cryptographic proofs in the 1993 publication by Mihir Bellare and Phillip Rogaway (1993). They are typically used when the cryptographic hash functions in the method cannot be proven to possess the mathematical properties required by the proof. A system that is proven secure when every hash function is replaced by a random oracle is described as being secure in the random oracle model, as opposed to secure in the standard model of cryptography. Random oracles are typically used as an ideal replacement for cryptographic hash functions in schemes where strong randomness assumptions are needed of the hash function's output. Such a proof generally shows that a system or a protocol is secure by showing that an attacker must require impossible behavior from the oracle, or solve some mathematical problem believed hard in order to break it. Not all uses of cryptographic hash functions require random oracles: schemes that require only one or more properties having a definition in the standard model (such as collision resistance, preimage resistance, second preimage resistance, etc.) can often be proven secure in the standard model (e.g., the Cramer–Shoup cryptosystem). Random oracles have long been considered in computational complexity theory, and many schemes have been proven secure in the random oracle model, for example Optimal Asymmetric Encryption Padding, RSA-FDH and Probabilistic Signature Scheme. In 1986, Amos Fiat and Adi Shamir showed a major application of random oracles – the removal of interaction from protocols for the creation of signatures. In 1989, Russell Impagliazzo and Steven Rudich showed the limitation of random oracles – namely that their existence alone is not sufficient for secret-key exchange. In 1993, Mihir Bellare and Phillip Rogaway were the first to advocate their use in cryptographic constructions. In their definition, the random oracle produces a bit-string of infinite length which can be truncated to the length desired. According to the Church–Turing thesis, no function computable by a finite algorithm can implement a true random oracle (which by definition requires an infinite description). In fact, certain artificial signature and encryption schemes are known which are proven secure in the random oracle model, but which are trivially insecure when any real function is substituted for the random oracle. Nonetheless, for any more natural protocol a proof of security in the random oracle model gives very strong evidence of the practical security of the protocol. In general, if a protocol is proven secure, attacks to that protocol must either be outside what was proven, or break one of the assumptions in the proof; for instance if the proof relies on the hardness of integer factorization, to break this assumption one must discover a fast integer factorization algorithm. Instead, to break the random oracle assumption, one must discover some unknown and undesirable property of the actual hash function; for good hash functions where such properties are believed unlikely, the considered protocol can be considered secure.
Views: 430 The Audiopedia
In this video I explain the fundamental concepts of cryptography. Encryption, decryption, plaintext, cipher text, and keys. Learn Math Tutorials Bookstore http://amzn.to/1HdY8vm Donate - http://bit.ly/19AHMvX STILL NEED MORE HELP? Connect one-on-one with a Math Tutor. Click the link below: https://trk.justanswer.com/aff_c?offer_id=2&aff_id=8012&url_id=232 :)
Views: 103863 Learn Math Tutorials
Modern day encryption is performed in two different ways. Check out http://YouTube.com/ITFreeTraining or http://itfreetraining.com for more of our always free training videos. Using the same key or using a pair of keys called the public and private keys. This video looks at how these systems work and how they can be used together to perform encryption. Download the PDF handout http://itfreetraining.com/Handouts/Ce... Encryption Types Encryption is the process of scrambling data so it cannot be read without a decryption key. Encryption prevents data being read by a 3rd party if it is intercepted by a 3rd party. The two encryption methods that are used today are symmetric and public key encryption. Symmetric Key Symmetric key encryption uses the same key to encrypt data as decrypt data. This is generally quite fast when compared with public key encryption. In order to protect the data, the key needs to be secured. If a 3rd party was able to gain access to the key, they could decrypt any data that was encrypt with that data. For this reason, a secure channel is required to transfer the key if you need to transfer data between two points. For example, if you encrypted data on a CD and mail it to another party, the key must also be transferred to the second party so that they can decrypt the data. This is often done using e-mail or the telephone. In a lot of cases, sending the data using one method and the key using another method is enough to protect the data as an attacker would need to get both in order to decrypt the data. Public Key Encryption This method of encryption uses two keys. One key is used to encrypt data and the other key is used to decrypt data. The advantage of this is that the public key can be downloaded by anyone. Anyone with the public key can encrypt data that can only be decrypted using a private key. This means the public key does not need to be secured. The private key does need to be keep in a safe place. The advantage of using such a system is the private key is not required by the other party to perform encryption. Since the private key does not need to be transferred to the second party there is no risk of the private key being intercepted by a 3rd party. Public Key encryption is slower when compared with symmetric key so it is not always suitable for every application. The math used is complex but to put it simply it uses the modulus or remainder operator. For example, if you wanted to solve X mod 5 = 2, the possible solutions would be 2, 7, 12 and so on. The private key provides additional information which allows the problem to be solved easily. The math is more complex and uses much larger numbers than this but basically public and private key encryption rely on the modulus operator to work. Combing The Two There are two reasons you want to combine the two. The first is that often communication will be broken into two steps. Key exchange and data exchange. For key exchange, to protect the key used in data exchange it is often encrypted using public key encryption. Although slower than symmetric key encryption, this method ensures the key cannot accessed by a 3rd party while being transferred. Since the key has been transferred using a secure channel, a symmetric key can be used for data exchange. In some cases, data exchange may be done using public key encryption. If this is the case, often the data exchange will be done using a small key size to reduce the processing time. The second reason that both may be used is when a symmetric key is used and the key needs to be provided to multiple users. For example, if you are using encryption file system (EFS) this allows multiple users to access the same file, which includes recovery users. In order to make this possible, multiple copies of the same key are stored in the file and protected from being read by encrypting it with the public key of each user that requires access. References "Public-key cryptography" http://en.wikipedia.org/wiki/Public-k... "Encryption" http://en.wikipedia.org/wiki/Encryption
Views: 497482 itfreetraining
Views: 186 Zariga Tongy
Views: 98 Zariga Tongy
I haven't GIVEN this presentation yet, but it's.. the slides and the words and the voice bits. Sorry about the visible cursor.
Views: 2427 Curtis
these days Passwords are required to be more and more complex, that is for the right reason. It is all too easy for a determined hacker to run a brute-force attack on a website in order to steal someone's password, especially if it is shorter. We have evolved from plain text password storage, to hashing a password, to appending salts and now even this is not considered adequate anymore. today let us find out how software giants like facebook or google stores user passwords. Whenever we create a new account in google of facebook they ask few informations like user name , email address or phone number , date of birth, gender and the most sensitive stuff the password. Once you enter all these informations and create a new account these onformations will go into the service provider’s user information data base , where all the informations except the passwords are saved in the form of plane texts . the passwords are hashed with very complicated algorithms . Hashing is a method of cryptography that converts any form of data into a unique string of text.it is a mathematical operation that is easy to perform, but extremely difficult to reverse. The difference between hashing and encryption is that encryption can be reversed, or decrypted, using a specific key, Whre as reversing hashed data requires a mammoth task.The most widely used hashing functions are MD5, SHA1 and SHA-256. Some hashing processes are significantly harder to crack than others.One major drawbacks of hashings is eventhough they cannot be deciphered using an alogorithms , some easy passwords can be creacked using Rainbow tables . which is a precomputed table for reversing cryptographic hash functions, usually for cracking password hashes. but rainbow tables contain the password hashes of only the passwords which are commonly used. Highly secure service providers like google and facebook use additional security features like salt and pepper. A salt is a non-secret, unique value in the database which is added to the password before it gets hashed.adding salt between the user defined password makes the passwords very strong and very difficult to identify using Rainbowtables . A pepper is a secret value or a key which is used to turn the hash, into a keyed hashing for message authentication. Once a pepper is added to the passoword the password cannot be reconstructed without a key. This could increase security if an attacker would only have access to the database and not to the place where the key is actually stored. Now if you ask me does facebook or google know their users passwords ? with all these cryptographic features added to the password . the only information about passord which is saved in the user information database of google or facebook is a heavily hashed data ,from which it is highly impossible to get the information about the passwords. not only google or facebook most of the reliable service providers wont store plane text passwords anymore . A big advice to techreveal viewers is that never take password streangth lightly , always make a password which is strong enough even withough salt and peppers .
Views: 656 Tech Reveal
The complete YouTube playlist can be viewed here: https://goo.gl/mjyDev This lesson explains the concept of the Elliptic Curve Cryptography(ECC), under the course, "Cryptography and Network Security for GATE Computer Science Engineering". The lesson explains the questions on the following subtopics: Elliptic Curve Cryptography(ECC) ECC - Public key cryptosystem ECC - Key Exchange ECC - Encryption and Decryption Elliptic curve Some important terminology and concepts are also illustrated, for the better understanding of the subject. For the entire course: https://goo.gl/aTMBNZ For more lessons by Ansha Pk: https://goo.gl/2DX9Wn Must watch for all the GATE/ESE/PSU Exams. Download the Unacademy Learning App from the Google Play Store here:- https://goo.gl/02OhYI Download the Unacademy Educator app from the Google Play Store here: https://goo.gl/H4LGHE Do Subscribe and be a part of the community for more such lessons here: https://goo.gl/UGFo7b Visit Our Facebook Group on GATE here: https://goo.gl/cPj5sb Elliptic Curve Cryptography(ECC) - GATE Computer Science - Unacademy
Views: 20804 Unacademy - GATE Preparation
The definition of a trapdoor one-way function is given in this video. This video also shows that the RSA function has a "trapdoor"
Views: 500 Leandro Junes
What is POST-QUANTUM CRYPTOGRAPHY? What does POST-QUANTUM CRYPTOGRAPHY mean? POST-QUANTUM CRYPTOGRAPHY meaning - POST-QUANTUM CRYPTOGRAPHY definition - POST-QUANTUM CRYPTOGRAPHY explanation. Source: Wikipedia.org article, adapted under https://creativecommons.org/licenses/by-sa/3.0/ license. SUBSCRIBE to our Google Earth flights channel - https://www.youtube.com/channel/UC6UuCPh7GrXznZi0Hz2YQnQ Post-quantum cryptography refers to cryptographic algorithms (usually public-key algorithms) that are thought to be secure against an attack by a quantum computer. This is not true for the most popular public-key algorithms, which can be efficiently broken by a sufficiently large quantum computer. The problem with the currently popular algorithms is that their security relies on one of three hard mathematical problems: the integer factorization problem, the discrete logarithm problem or the elliptic-curve discrete logarithm problem. All of these problems can be easily solved on a sufficiently powerful quantum computer running Shor's algorithm. Even though current, publicly known, experimental quantum computers are too small to attack any real cryptographic algorithm, many cryptographers are designing new algorithms to prepare for a time when quantum computing becomes a threat. This work has gained greater attention from academics and industry through the PQCrypto conference series since 2006 and more recently by several workshops on Quantum Safe Cryptography hosted by the European Telecommunications Standards Institute (ETSI) and the Institute for Quantum Computing. In contrast to the threat quantum computing poses to current public-key algorithms, most current symmetric cryptographic algorithms and hash functions are considered to be relatively secure against attacks by quantum computers. While the quantum Grover's algorithm does speed up attacks against symmetric ciphers, doubling the key size can effectively block these attacks. Thus post-quantum symmetric cryptography does not need to differ significantly from current symmetric cryptography.
Views: 251 The Audiopedia