[B! information][computer science] kenzan8000のブックマーク

kenzan8000 id:kenzan8000

informationとcomputer scienceに関するkenzan8000のブックマーク (17)

RSA encryption: Step 4 | Journey into cryptography | Computer Science | Khan Academy
kenzan8000 2020/04/25
Alice: create a public key by two random prime numbers multiplication, get the phi, create exponent for another public key(create a private key), and send two public keys. Bob: create encrypted message by the public keys and a new private key, and send it. Alice: decrypt message by the private key.

rsa

cryptography

computer science

information
リンク
Diffie-hellman key exchange | Journey into cryptography | Computer Science | Khan Academy
kenzan8000 2020/04/25
encryption used shared private key and public keys and discrete logarithm problem. easy to perform between Alice and Bob but hard for Eve to reverse because so many numbers of trial are needed to reverse.

cryptography

computer science

information

discrete logarithm

math
リンク
Elegant Compression in Text (The L.Z.77 Method) - Computerphile - YouTube
Text compression methods such as LZ can reduce file sizes by up to 80%. Professor Brailsford explains the nuts and bolts of how it is done. Original Compression film: http://youtu.be/Lto-ajuqW3w EXTRA BITS - Text Compression meets probabilities: http://youtu.be/cCDCfoHTsaU Cross Site Scripting with Tom Scott: http://youtu.be/L5l9lSnNMxg http://www.facebook.com/computerphile https://twitter.com/c
kenzan8000 2020/04/23
basic idea of text compression. reuse the character pattern already occurred. use data structure like the pointer and length for the implementation. also, the frequency of word or character pattern fits better than each character does. it is called adaptive compression or arithmetic compression.

computer science

information

compression

data structure

algorithm

statistics
リンク
Upside Down Trees (Huffman Trees) - Computerphile - YouTube
How do we derive the most compact codes for a situation? Huffman Trees can help. Professor Brailsford explains how computer scientists like their trees to be upside down. "Entropy in Compression - Computerphile" precedes this: http://www.youtube.com/watch?v=M5c_RFKVkko EXTRA BITS: More on Huffman Trees: http://www.youtube.com/watch?v=DV8efuB3h2g Error Correction: http://www.youtube.com/watch?v=
kenzan8000 2020/04/23
for entropy reduction. pick up two lower probabilities first as a deepest branch. repeat it until you have built complete binary tree. then you can assign bit codes to each. less bit codes are assigned to frequently used data.

computer science

information

compression

statistics

huffman

tree
リンク
Pseudorandom number generators | Computer Science | Khan Academy
kenzan8000 2020/04/23
you cannot predict randomness. pseudorandom is predicable because of the repetition but difficult if the seed is long. need lots of computation resource to decrypt

cryptography

computer science

information
リンク
The Enigma encryption machine | Journey into cryptography | Computer Science | Khan Academy
kenzan8000 2020/04/23
rotor encryption (enigma): state allows you to encrypt one letter to another. state is defined by rotors. key space = rearrange rotor x numbers on each rotor; state change happens by every type since rotor rotates. only initial state is shared

cryptography

statistics

computer science

information
リンク
エニグマ暗号機による通信方法
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kenzan8000 2020/04/23
cryptography

statistics

computer science

information
リンク
パリティビットの意味と誤り検出、誤り訂正の方法 - 具体例で学ぶ数学
kenzan8000 2020/04/21
detect error if number of 1 or 0 bits seems wrong as the parity bit (row in 2d matrix). then add error correction codes (other parity bits representing column in 2d matrix). if both parity bit and error correction code seem wrong, you can figure out the exact bit (coordinate) that seems wrong.

computer science

information

parity bit

error
リンク
Error correction | Journey into information theory | Computer Science | Khan Academy
kenzan8000 2020/04/21
computer science

information

error

parity bit
リンク
Compression codes | Journey into information theory | Computer Science | Khan Academy
kenzan8000 2020/04/21
computer science

information

huffman

encoding

entropy
リンク
Information entropy | Journey into information theory | Computer Science | Khan Academy
kenzan8000 2020/04/20
information

entropy

computer science

probability
リンク
Origin of Markov chains | Journey into information theory | Computer Science | Khan Academy
kenzan8000 2020/04/20
computer science

information

markov chains

statistics
リンク
Measuring information | Journey into information theory | Computer Science | Khan Academy
kenzan8000 2020/04/20
computer science

information

bit

logarithm
リンク
Introduction to channel capacity | Journey into information theory | Computer Science | Khan Academy
kenzan8000 2020/04/20
computer science

information

baud

symbol space
リンク
Morse code and the information age | Computer Science | Khan Academy
kenzan8000 2020/04/19
information

computer science

binary

encoding
リンク
Visual telegraphs (case study) | Computer Science | Khan Academy
kenzan8000 2020/04/19
information

computer science

binary

encoding
リンク
Source encoding | Journey into information theory | Computer Science | Khan Academy
kenzan8000 2020/04/19
encoding

computer science

information
リンク
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