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Practical Cryptography
Cryptanalysis
This section documents the ways in which many cryptographic ciphers can be cryptanalysed and broken. The easiest ciphers to break are the ones which have existed for a long time. With th...
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Practical Cryptography
The simple substitution cipher is a cipher that has been in use for many hundreds of years (an excellent history is given in Simon Singhs 'the Code Book'). It basically consists of substituting every ...
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Practical Cryptography
Although most people claim they're not familar with
cryptography, they are often familar with the concept of ciphers, whether or not they are actually concious of it. Recent films such as
The Da Vin...
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Practical Cryptography
Invented by Lester S. Hill in 1929, the Hill cipher is a polygraphic substitution cipher based on linear algebra. Hill used matrices and matrix multiplication to mix up the plaintext.
To counter charg...
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Practical Cryptography
Identifying Unknown Ciphers
The scenario: you have an unknown cipher and you need to decipher it. You don't know the key, or even the algorithm that was used to create the ciphertext! What can be done...
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Practical Cryptography
The columnar transposition cipher is a fairly simple, easy to implement cipher. It is a transposition
cipher that follows a simple rule for mixing up the characters in the plaintext
to form the ciph...