Block cipher on a different character set (x-post from r/crypto) via /r/learnprogramming


Block cipher on a different character set (x-post from r/crypto)

As I understand, popular block ciphers like DES, AES operate on ASCII/unicode that use all characters represented in a byte ( 256 characters for ASCII). Is there a variation on a block cipher that allow encryption on a (say) 52 length character set?

For example if i have a plaintext containing only alphabets and encrypt it with this modified block cipher, I should get a ciphertext containing only alphabets.

If the character set is of 2n length, i could convert it to binary and use ordinary DES/AES. But if i have a 56 length character set, i couldn't use that method since a portion of the bits might be unused. ( 55 = 110111_b. when encrypting i could get 61 = 111101_b as output which is invalid according to my application)

Is there such an algorithm?

Submitted July 17, 2017 at 01:02PM by second_second
via reddit http://ift.tt/2valX46

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