- Bookcover of Permutation Cipher
- Booktitle:
-
Permutation Cipher
Permutation, Plaintext, Ciphertext
PlacPublishing (2011-12-17 )
eligible for voucher
- ISBN-13:
978-613-8-90212-6
- ISBN-10:
- 6138902122
- EAN:
- 9786138902126
- Book language:
- Blurb/Shorttext:
- Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In classical cryptography, a permutation cipher is a transposition cipher in which the key is a permutation.Because the cipher operates on blocks of size e, the plaintext and the ciphertext have to have a length which is some multiple of e. This causes two weaknesses in the system: first, the plaintext may have to be padded (if the padding is identifiable then part of the key is revealed) and second, information relating to the length of the key is revealed by the length of the ciphertext. To see this, note that if the ciphertext is of length i then e must be one of the divisors of i. With the different possible key sizes different possible permutations are tried to find the permutation which results in the highest number of frequent bigrams and trigrams as found in the underlying language of the plaintext. Trying to find this permutation is essentially the same problem encountered when analysing a columnar transposition cipher: multiple anagramming.
- Publishing house:
- PlacPublishing
- Website:
- http://www.betascript-publishing.com
- Edited by:
- Epimetheus Christer Hiram
- Number of pages:
- 56
- Published at:
- 2011-12-17
- Stock:
- Available
- Category:
- General Social sciences
- Price:
- 29.00 €
- Keywords:
- Permutation, Plaintext, Ciphertext, cipher
