Two encryption methods of classical passwords

Classical encryption algorithm: permutation password

The principle of permutation cipher algorithm is not to change plaintext characters, but only to change the arrangement order of characters in plaintext, thus realizing the encryption of plaintext information. Permutation passwords are sometimes called transposition passwords.

Matrix transpose is a common method to realize permutation cipher. It arranges the letters in the text into a matrix in a given order, and then recombines the letters in the matrix in the order provided by the key, thus forming ciphertext. For example, plain text is an attack.

begin

exist

5. The key is ciphertext, and plaintext is arranged in the matrix in the form of 6 columns per row, forming the following form:

a

t

t

a

c

k

b

e

g

I

n

s

a

t

f

I

v

e

According to the order of the letters in the alphabet, give an arrangement:

1

2

three

four

five

six

f

=

1

four

five

three

2

six

According to the above arrangement, the letters in the original matrix are arranged in the order of 1 column, 4 columns, 5 columns, 3 columns, 2 columns and 6 columns, and the form is as follows:

a

a

c

t

t

k

b

I

n

g

e

s

a

I

v

f

t

e

So as to obtain the ciphertext: aacttkbingesaivfte