Fairplay Cipher

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Working

Key

Enter keyword (preferably without repeated letters): qwerty Formatted key: QWERTY

Enter keyword (preferably without repeated letters): hello Formatted key: HELO

Grid

Formatted key: QWERTY

Q   W   E   R   T
Y   A   B   C   D
F   G   H   I   K
L   M   N   O   P
S   U   V   X   Z

Formatted key: HELO

H   E   L   O   A
B   C   D   F   G
I   K   M   N   P
Q   R   S   T   U
V   W   X   Y   Z

Input

Enter string to be encrypted: qwerty Formatted string: QWERTY

Enter string to be encrypted: hell Formatted string: HELXLX

Enter string to be encrypted: james Formatted string: JAMESX

Enter string to be encrypted: hello Formatted string: HELXLO

Enter string to be encrypted: helllo Formatted string: HELXLXLO

Enter string to be encrypted: haxx Formatted string: HAXQXQ

Enter string to be encrypted: haxxo Formatted string: HAXQXO

Enter string to be encrypted: hello world Formatted string: HELXLOWORLDX

Encryption

Take key input and format it using the above algorithm for keys, removing repeated characters. Form a grid using the above algorithm. Take input to be encrypted and format it using the above algorithm for strings.

1> take letters in pairs from formatted input ex: QWERTY --> QW ER TY

2> if the pair of letters is in the same column in the grid, shift down ex: QS --> YQ Q Y F L S

3> if the pair of letters is in the same row in the grid, shift right ex: KP --> MI I K M N P

4> if the pair of letters is the diagonal of a rectangle, switch to the other diagonal horizontally ex: DS --> GQ D F G I K M Q R S

5> join all pairs and return encrypted string

Decryption

Take key input and format it using the above algorithm for keys, removing repeated characters Form a grid using the above algorithm Take encrypted input

1> take letters in pairs from formatted input ex: QWERTY --> QW ER TY

2> if the pair of letters is in the same column in the grid, shift up ex: YQ --> QS Q Y F L S

3> if the pair of letters is in the same row in the grid, shift left ex: MI --> KP I K M N P

4> if the pair of letters is the diagonal of a rectangle, switch to the other diagonal horizontally ex: GQ --> DS D F G I K M Q R S