Description: Playfair Cipher
1.not even the large number of keys in a monoalphabetic cipher provides security
2.one approach to improving security was to encrypt multiple letters
3.the Playfair Cipher is an example
4.invented by Charles Wheatstone in 1854,but named after his friend Baron Playfair
Playfair Key Matrix
1.a 5X5 matrix of letters based on a keyword
2.fill in letters of keyword (sans duplicates)
3.fill rest of matrix with other letters
Encrypting and Decrypting
-plaintext is encrypted two letters at a time
1. if a pair is a repeated letter, insert filler like X’
2. if both letters fall in the same row, replace each with letter to right (wrapping back to start from end)
3. if both letters fall in the same column, replace each with the letter below it (again wrapping to top from
bottom)
4. otherwise each letter is replaced by the letter in the same row and in the column of the other letter of the pair -Playfair Cipher
1.not even the large number of keys in a monoalphabetic cipher provides security
2.one approach to improving security was to encrypt multiple letters
3.the Playfair Cipher is an example
4.invented by Charles Wheatstone in 1854,but named after his friend Baron Playfair
Playfair Key Matrix
1.a 5X5 matrix of letters based on a keyword
2.fill in letters of keyword (sans duplicates)
3.fill rest of matrix with other letters
Encrypting and Decrypting
-plaintext is encrypted two letters at a time
1. if a pair is a repeated letter, insert filler like X’
2. if both letters fall in the same row, replace each with letter to right (wrapping back to start from end)
3. if both letters fall in the same column, replace each with the letter below it (again wrapping to top from
bottom)
4. otherwise each letter is replaced by the letter in the same row and in the column of the other letter of the pair Platform: |
Size: 133120 |
Author:黃文岩 |
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Description: Substitution ciphers are probably the most common form of cipher. They work by replacing each letter of the plaintext (and sometimes puntuation marks and spaces) with another letter (or possibly even a random symbol).
A monoalphabetic substitution cipher, also known as a simple substitution cipher, relies on a fixed replacement structure. That is, the substitution is fixed for each letter of the alphabet. Thus, if a is encrypted to R , then every time we see the letter a in the plaintext, we replace it with the letter R in the ciphertext.-Substitution ciphers are probably the most common form of cipher. They work by replacing each letter of the plaintext (and sometimes puntuation marks and spaces) with another letter (or possibly even a random symbol).
A monoalphabetic substitution cipher, also known as a simple substitution cipher, relies on a fixed replacement structure. That is, the substitution is fixed for each letter of the alphabet. Thus, if a is encrypted to R , then every time we see the letter a in the plaintext, we replace it with the letter R in the ciphertext. Platform: |
Size: 1024 |
Author:EASHAN |
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Description: 古典密码中的单表置换密码的实现，C++初步-Classical passwords in a single table to achieve replacement passwords, C++ preliminary Platform: |
Size: 1879040 |
Author:马艾静 |
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Description: substitution cipher is the method of encoding in which unit of plain text are replaced by cipher text. Monoalphabetic cipher uses a fixed message over entire message.A monoalphabetic cipher uses fixed substitution over the entire message.The monoalphabetic substitution takes a letter of an alphabet and substitutes it with another letter, this way a ciphertext is generated. The way of converting is fixed. A character of the plaintext will be replaced by the same ciphertext character, during the entire ciphertext. There is no additional key. The only way of security is to keep the substitution-table secret.
A popular example for the monoalphabetic substitution is the caesar cipher.
Platform: |
Size: 9216 |
Author:mathi |
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Description: The Vigenère cipher is a method of encrypting alphabetic text by using a series of different Caesar ciphers based on the letters of a keyword. It is a simple form of polyalphabetic substitution.Though the cipher is easy to understand and implement, for three centuries it resisted all attempts to break it this earned it the description le chiffre indéchiffrable (French for the indecipherable cipher ). Many people have tried to implement encryption schemes that are essentially Vigenère ciphers.[3] Friedrich Kasiski was the first to publish a general method of deciphering a Vigenère cipher.Unlike the monoalphabetic ciphers, polyalphabetic ciphers are not susceptible to frequency analysis, as more than one letter in the plaintext can be represented by a single letter in the encryption.-The Vigenère cipher is a method of encrypting alphabetic text by using a series of different Caesar ciphers based on the letters of a keyword. It is a simple form of polyalphabetic substitution.Though the cipher is easy to understand and implement, for three centuries it resisted all attempts to break it this earned it the description le chiffre indéchiffrable (French for the indecipherable cipher ). Many people have tried to implement encryption schemes that are essentially Vigenère ciphers.[3] Friedrich Kasiski was the first to publish a general method of deciphering a Vigenère cipher.Unlike the monoalphabetic ciphers, polyalphabetic ciphers are not susceptible to frequency analysis, as more than one letter in the plaintext can be represented by a single letter in the encryption. Platform: |
Size: 10240 |
Author:mathi |
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Description: In cryptography, a Caesar cipher, also known as Caesar s cipher, the shift cipher, Caesar s code or Caesar shift, is one of the simplest and most widely known Platform: |
Size: 3072 |
Author:neharika |
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