Compilation and Running

Linux

Encryption

make clean make encryption ./build/encryption -n "CRYPTOLOGY IS THE PRACTICE AND STUDY OF TECHNIQUES FOR SECURE COMMUNICATION IN THE PRESENCE OF THIRD PARTIES CALLED ADVERSARIES." -d 4 -r 5 'CYLIETSTGENC AEUEERRCLMU OPYAICE SRIPAOSTSTN TEECID IDPYDONDEAVR NCHAEHSTOFRCT EOSI TFNIN QD HHIARFORPU.S OEUE ER CIS RTMLAC'

Decryption

make clean make decryption ./build/decryption -n "TAOTINEN KAT I ODIOAEI OHHLSCTE TTETOEL BI IHI GAO EPSEA TO SS EEK ELRCPTSIY EANRPHMCYEK E CREAAIEJURTE IEASHI MA DRN RH AUWTA RF EFTFHENTPSF Q TAILB E TTECAPMSIYIY SRPURNTBL YCL OANAO E TVREAOSHOTTNULSRHK" -d 3 -r 3 'THE RAILFENCE CIPHER IS AN EASY TO APPLY TRANSPOSITION CIPHER THAT JUMBLES UP THE ORDER OF THE LETTERS OF A MESSAGE IN A QUICK CONVENIENT WAY IT ALSO HAS THE SECURITY OF A KEY TO MAKE IT A LITTLE BIT HARDER TO BREAK'

Automated tests

make clean make tests

Windows

From a Developer Console: make.bat cd build

Encryption

encryption.exe -n "CRYPTOLOGY IS THE PRACTICE AND STUDY OF TECHNIQUES FOR SECURE COMMUNICATION IN THE PRESENCE OF THIRD PARTIES CALLED ADVERSARIES." -d 4 -r 5 'CYLIETSTGENC AEUEERRCLMU OPYAICE SRIPAOSTSTN TEECID IDPYDONDEAVR NCHAEHSTOFRCT EOSI TFNIN QD HHIARFORPU.S OEUE ER CIS RTMLAC'

Decryption

decryption.exe -n "TAOTINEN KAT I ODIOAEI OHHLSCTE TTETOEL BI IHI GAO EPSEA TO SS EEK ELRCPTSIY EANRPHMCYEK E CREAAIEJURTE IEASHI MA DRN RH AUWTA RF EFTFHENTPSF Q TAILB E TTECAPMSIYIY SRPURNTBL YCL OANAO E TVREAOSHOTTNULSRHK" -d 3 -r 3 'THE RAILFENCE CIPHER IS AN EASY TO APPLY TRANSPOSITION CIPHER THAT JUMBLES UP THE ORDER OF THE LETTERS OF A MESSAGE IN A QUICK CONVENIENT WAY IT ALSO HAS THE SECURITY OF A KEY TO MAKE IT A LITTLE BIT HARDER TO BREAK'

Encryption algorithm

Input:

n: Plain text d: number of rows of the table r: number of repetitions

Algorithm

1. Allocate a 2D array of d rows and length(plain text) columns.
2. Repeat r times 3) to 4).
3. initialize the 2D array with 0's ; Assuming plain text doesn't have any 0.
4. [i = 0, j = 0, p = 1] foreach c in plain: array[ i ][ j ] <-- c j += 1 if i + 1 == rows then p <-- -1 ; Switch direction to up else if i == 0 then p <-- 1 ; Switch direction to down i += p
5. res <-- "" foreach i in [0, rows): foreach j in [0, length(plain text)): if array[ i ][ j ] != 0 then res <-- res + array[ i ][ j ] end if
6. return res

Decryption algorithm

Input:

n: cipher text d: number of rows of the table r: number of repetitions

Algorithm

1. Allocate a 2D array of d rows and length(cipher) columns.
2. Repeat r times:
3. Do Step 3) and 4) of Encryption with Plain a 1's String with the same length as Cipher.
4. [n <-- 0] foreach i in [0, rows): foreach j in [0, length(plain text)): if array[ i ][ j ] != 0 then array[ i ][ j ] <-- cipher[n] n += 1 end if end for end for
5. Do Step 4) of Encryption but swapping the assignment c <-- array[ i ][ j ]
6. return calculated plain string in 5).