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Videos uploaded by user “Theoretically”
Vigenere Cipher - Decryption (Known Key)
 
03:18
This video shows how to decrypt the ciphertext when the key is known. Decryption (unknown key): http://youtu.be/LaWp_Kq0cKs Encryption: http://youtu.be/izFivfLjD5E
Views: 23229 Theoretically
Affine Cipher Encryption
 
06:15
gcd: https://www.youtube.com/watch?feature=player_detailpage&v=WA4nP-iPYKE Decryption: http://youtu.be/XFxFPBKFVe8
Views: 21339 Theoretically
Schnorr Digital Signature
 
04:59
In this video I briefly go over the advantage to the Schnorr signature, and how to sign and verify.
Views: 7059 Theoretically
Vigenere Cipher - Encryption
 
05:09
This video is about the Vigenere Cipher: years used, key format, encryption. Note: sorry, I may have mispronounced names. Decryption (known key): http://youtu.be/oHcJ4QLiiP8 Decryption (unknown key): http://youtu.be/LaWp_Kq0cKs
Views: 23555 Theoretically
Affine Cipher - Decryption (Known Plaintext Attack)
 
07:04
In this video I talk about ways to decrypt the Affine Cipher when the key is NOT known. Specifically, I go over an example of the known plaintext attack. 3^(-1) = 9 (mod 26) math worked out (Euclidean Algorithm): 1. Forwards: 26 = 3(8) + 2 3 = 2(1) + 1 2. Backwords: 1 = 3 - 2(1) 1 = 3(1) - (26 - 3(8))(1) 1 = 3(1) - 26 + 3(8) 1 + 26 = 3(9) 1 (mod 26) = 3(9) Hence 9 is the inverse. Links: -Affine Encryption: https://www.youtube.com/watch?v=_E8rSP0uAIY -Affine Decryption (Known Key): https://www.youtube.com/watch?v=XFxFPBKFVe8 -Euclidean Algorithm: https://www.youtube.com/watch?v=K5nbGbN5Trs
Views: 18506 Theoretically
Affine Cipher Decryption - Known Key
 
09:29
This video is the second Affine Cipher video. Decryption when the key is known. How to find multiplicative inverse (x^-1 mod n): https://www.youtube.com/watch?v=K5nbGbN5Trs Encryption: http://youtu.be/_E8rSP0uAIY
Views: 20359 Theoretically
Vigenere Cipher - Decryption (Unknown Key)
 
17:45
This video shows the process (thoroughly) of how to find the key when you don't have it. English alphabet frequencies: http://www.math.cornell.edu/~mec/2003-2004/cryptography/subs/frequencies.html Decryption (known key): http://youtu.be/oHcJ4QLiiP8 Encryption: http://youtu.be/izFivfLjD5E
Views: 114429 Theoretically
Elliptic Curve ElGamal Cryptosystem
 
03:48
In this video I primarily do through the Elliptic Curve ElGamal crytposystem (Bob's variables/computations, Alice's variables/computations, what is sent, and how it is decrypted by Bob). In addition, I go over the basics of elliptic curves such as their advantages and how they are written. Digital Signatures - ElGamal: https://www.youtube.com/watch?v=Jo3wHnIH4y832,rpd=4,rpg=7,rpgr=0,rpm=t,rpr=d,rps=7 Reference: Trappe, W., & Washington, L. (2006). Introduction to cryptography: With coding theory (2nd ed.). Upper Saddle River, N.J.: Pearson Prentice Hall.
Views: 8894 Theoretically
Prime Factorization - Fermat Algorithm
 
02:44
Description and example of getting the prime factors of a number using the Fermat algorithm. Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 9150 Theoretically
Squares Mod p
 
02:11
How to solve for a squared number when you're working mod p. (i.e. x^2 = number mod p) Reference: http://www.math.brown.edu/~jhs/MA0042/FRINTNewCh2324.pdf
Views: 3399 Theoretically
Miller-Rabin Primality Test
 
09:23
Here's a second (better) example for how to use the Miller-Rabin primality test.
Views: 32190 Theoretically
Finding Minimum Distance
 
08:24
In this video I briefly explain what minimum distance is and why it is helpful. Then I explain how to find it "the long way" and the "shortcut." Also during the process, I explain what Hamming Weight and Distance are and how to find them. Codewords from Generating Matrix Video: https://www.youtube.com/watch?v=z4WE2qpvaF8
Views: 22527 Theoretically
BIG Exponents - Modular Exponentiation, Fermat's, Euler's
 
16:02
How to deal with really big exponents using the three main methods: Modular Exponentiation, Fermat's Little Theorem, and Euler's Theorem. Also explains which method to pick. Table of contents: Which to pick? - 0:47 Fermat's Example - 1:39 Modular Exponentiation Example - 4:43 Euler's Example - 10:13
Views: 31572 Theoretically
Linear Codes Introduction
 
06:07
This video is a brief introduction to linear codes: dimensions, G (generating matrix), H (parity check matrix), their forms. Also gives an example of how to convert between G and H. Here is the formal definition of a Linear Code: A linear code of dimension k and length n over a field F is a k-dimension subspace of F^n. Such a code is called an [n,k] code. If the minimum distance of the code is d, then the code is called an [n,k,d] code. Citation: Trappe, W., & Washington, L. (2006). Introduction to cryptography: With coding theory (2nd ed., pp. 392-420). Upper Saddle River, N.J.: Pearson Prentice Hall. Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 67590 Theoretically
Hamming Code - Errors
 
04:37
How to detect and correct an error using the Hamming Code. Hamming codes are a type of linear code, see link for intro to linear code: https://www.youtube.com/watch?v=oYONDEX2sh8 Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 1780 Theoretically
Codewords From Generating Matrix
 
06:59
In this video I describe how to get your codewords from your generative matrix. MISTAKE: I put 4^2, rather than 2^4. In my case both =16 so it didn't change the rest of the problem. But the reasoning is still the same: we have a binary code (2) and a length of 4... so we should calculate 2^4=(options^length). I apologize for this mistake and hope it doesn't cause too much confusion.
Views: 57408 Theoretically
Lise Where's-My-Nobel-Prize Meitner
 
02:53
A video about Lise Where's-My-Nobel-Prize Meitner, in which a brilliant physicist helps split the atoms and does not receive a nobel prize.
Views: 387 Theoretically
Euclidean Algorithm and Multiplicative Inverse (Ex. 2)
 
07:49
This video is a second example of how to find a multiplicative inverse using the Euclidean algorithm. (Problems that look like this: x^-1 mod n = ??) -For the first example: http://youtu.be/K5nbGbN5Trs -For how to use the algorithm to find a gcd: http://youtu.be/WA4nP-iPYKE
Views: 6135 Theoretically
Primitive Roots Method 1
 
02:07
The second method for testing whether alpha is a primitive root mod p. Description of primitive roots is in the Primitive Roots pt. 1 video. Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 22234 Theoretically
Emmy Noether
 
03:28
Ever heard of Emmy Noether? No? Now you have. Watch this video to learn about one of mathematic's greatest.
Views: 2327 Theoretically
Digital Signatures - ElGamal (pt.1)
 
03:50
This video introduces the use of ElGamal cryptosystem as type of digital signature. Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 10166 Theoretically
Pohlig-Hellman Algorithm
 
14:24
This video is an example of using the Pohlig-Hellman Algorithm to solve a discrete log problem.
Views: 10377 Theoretically
Euclidean Algorithm and Multiplicative Inverse (Ex. 1)
 
12:58
This video gives an example of how to use the Euclidean algorithm for finding a multiplicative inverse like this: x^-1 mod n = ?. For a second example: http://youtu.be/V2Ae-yEGq08 For using the algorithm to find gcd instead: http://youtu.be/WA4nP-iPYKE
Views: 33128 Theoretically
Hedy I'm-Smarter-Than-You Lamarr
 
01:48
A lesson on what to do if you happen to end up marrying a Facist weapons manufacturer.
Views: 1596 Theoretically
Digital Signatures - RSA
 
03:33
This video shows how RSA encryption is used in digital signatures. Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 9821 Theoretically
Hash Functions
 
08:05
0:00-4:15 - A conceptual overview of hash functions and their requirements. 4:15-end - Hash functions in digital signatures use. For review on how RSA signatures work, see: https://www.youtube.com/watch?v=DIfOvWymmP0 Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 17441 Theoretically
Tangent Line Problem
 
06:54
This video is a brief overview of the classic calculus problem, "The Tangent Line Problem." This problem is a typical introduction to to the topic of calculus, along with "The Area Problem." Course: Calculus I Book reference: Calculus, 9e. By Ron Larson and B. Edwards. Chapter 1.1 Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 201 Theoretically
Basic Principle
 
02:00
A brief description of the "Basic Principle" and how it can be used to test for primality.
Views: 175 Theoretically
Solve for x: Intro, Pt.  1 (Add./Sub.)
 
06:31
In this video I introduce the goal when solving for x, as well as how, when, and why to use adding or subtracting as a tool in solving for x. Links for more Solving for x: Pt. 2 - Using Multiplication: http://youtu.be/OzPpDGj-diA Pt. 3 - Using Division: http://youtu.be/yg0Dca7qrag
Views: 102 Theoretically
Digital Signature - ElGamal (pt. 3 - Same k Attack)
 
07:39
This video goes over "same k attack" on ElGamal digital signatures. Also see pt.1 (Intro to ElGamal dig. sig) and pt.2 (why ElGamal works), respectively: https://www.youtube.com/watch?v=Jo3wHnIH4y8 https://www.youtube.com/watch?v=cYbJDhTKAXU Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 1676 Theoretically
Alice Ball
 
02:02
The young chemist who did what so many researchers could not.
Views: 1295 Theoretically
Primality Testing - Miller-Rabin
 
05:40
Using the Miller-Rabin (probabilistic) primality test. NOTE: if bo (and only bo) had been either +1 OR -1, n would be prime (it was 263, in this example). BUT for b1, b2, and so on, +1 implies composite, -1 implies prime. Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 38688 Theoretically
System of Linear Equations with Two Variables (pt. 1)
 
06:23
This video introduces systems of linear equations with two variables (from a college algebra standpoint) and shows how to determine whether a given ordered pair is a solution to the system. Course: College Algebra Book reference: College Algebra Essentials, 3e. By Robert Blitzer. Chapter 5.1 Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 97 Theoretically
Chinese Remainder Theorem
 
03:02
Chinese Remainder Theorem (in Basic Number Theory) Statement of the theorem and how to use it to solve for some x (mod m*n) given x = a (mod m) and x = b (mod n). Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 2565 Theoretically
Polynomials Introduction: Form, y-int., Max. Relative Extrema, Max. Real Zeros
 
15:36
This video introduces polynomials from a Pre-Calculus standpoint. It goes over the form we write them in, the y-intercept, the maximum number of relative extrema, and the maximum number of real zeros. It also goes over the terms "degree", "leading coefficient", and "constant term." Table of contents: Written form - 0:00 Degree - 5:30 Leading Coefficient - 6:00 Constant term - 6:47 Max Real Zeros - 8:05 Max Relative Extrema - 11:07 y-Intercept - 13:47
Views: 184 Theoretically
Digital Signature - ElGamal (pt. 2)
 
04:59
This video shows why ElGamal digital signatures work with a bit more detail. See ElGamal Digital Signature pt. 1 (which introduces the idea) https://www.youtube.com/watch?v=Jo3wHnIH4y8 Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 2341 Theoretically
Intro to Cryptography
 
10:45
This video gives a general introduction to cryptography WITHOUT actually doing any math. Terms covered include cryptology vs cryptography vs cryptanalysis, symmetric vs public key systems, and "coding theory." NOTE: Yes, I said and wrote "cryptOanalysis" when it's actually "cryptanalysis" without the "O". My bad.
Views: 836 Theoretically
Proof By Induction Made Ridiculous
 
17:35
This gives a brief overview of proof by induction using the classic ridiculous book analogy. Then I give an actual example worked out. Then to cap it off, I give an explanation of why it actually works. Table of Contents: Book Example: 0:24 What is that thing?: 3:00 Example Step 1: 7:38 Example Step 2: 9:03 Example Step 3: 10:09 WHY?: 15:47
Views: 309 Theoretically
Primality Testing - Fermat
 
03:15
Using the Little Fermat Theorem to test for primality. MISTAKE: Everywhere it says 561, it should say 23. Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 3883 Theoretically
Basics of Inequalities in Math
 
05:43
In this video I talk about what inequalities are, mean, and do. Also, how to look at an inequality and determine whether it is true/false. Has examples and practice problems. Please post any questions in the comments! Answers to practice problems: 1. True 2. False 3. True 4. False 5. True 6. True 7. False 8. False
Views: 77 Theoretically
Types of Chemical Bonds
 
13:39
The essentials of chemical bonds. Includes Covalent (polar, non-polar) and non-covalent (ionic, dipole, hydrogen bonding, Van der Waal). Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 100 Theoretically
Euclidean Algorithm and GCDs (Ex. 1)
 
03:21
This video gives an example of how and why the Euclidean algorithm is used to find the gcd of two numbers. Like so: gcd(x,y) = ?. -Here's a second example:http://youtu.be/CtUsUnHz9ek -Here's an example of using the Euclidean algorithm to find a multiplicative inverse: http://youtu.be/K5nbGbN5Trs
Views: 1368 Theoretically
Barbara McClintock
 
02:54
Barbara McClintock: professional pre-genetics geneticist, corn-experimenter, and award-collector.
Views: 482 Theoretically
Primitive Roots Method 2
 
02:44
This video describes what a primitive roots is. Also, how to test if a number (alpha) is primitive for a low/small modulus. Also note that there is a more efficient way of testing for a primitive root (if p-1 is easily factorable), which is discussed in part 2: https://www.youtube.com/watch?v=I-N8oQmeXwU Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 9770 Theoretically
Essential Stuff about Enzymes
 
10:00
This video covers the essential facts about enzymes that you would need to know in, say, a introductory biology class. It covers what they are, what the do, and why we need them, plus a few other tid-bits. Questions? Feel free to post them in the comments and I'll do my best to answer!
Views: 29 Theoretically
How and Why to Factor
 
10:16
In this video, I show how and why to factor in multiple different cases. For more examples: https://www.youtube.com/watch?v=kcv7HTUu6Qg&feature=youtu.be Please post any questions in comments!
Views: 50 Theoretically
Nature's Glow-in-the-dark!
 
09:49
In this video I talk about BIOLUMINESCENCE. Specifically what it is, HOW it works, and WHY animals have it. NatGeo Link: http://education.nationalgeographic.com/education/encyclopedia/bioluminescence/?ar_a=1 Glowing Tree Link: http://www.newscientist.com/article/mg20827885.000-glowing-trees-could-light-up-city-streets.html#.VRBZuDr7TA9
Views: 160 Theoretically
Affine Cipher on Maple
 
00:44
How to encrypt and decrypt the affine cipher using Maple software. Code from Into to Crypto and Coding Theory 2nd ed. by W. Trappe and LC Washington.
Views: 696 Theoretically
Vigenere Cipher on Maple
 
07:00
How to decrypt the vigenere cipher on Maple software. Note: at 1:03 when I said "original text" I was referring to the ciphertext.
Views: 2755 Theoretically
Making a Graph from an Equation of a Straight Line
 
06:04
In this video I show how to draw the graph of a straight line when you are given an equation. Making an Equation from a Graph: https://www.youtube.com/watch?v=7ooI_fGbFNM Intro to Graph of a Line: https://www.youtube.com/watch?v=PrKtWrQJq5A
Views: 68 Theoretically

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