def decryptVigenere(charList, keyString):
""" (list, str) -> str
Decrypt the passed ciphertext list charList, encrypted with the Vigenere cipher
using the passed key keyString.
>>> decryptVigenere(['X', 'S', 'F', 'J', 'D', 'J', 'M', 'N', 'R', 'F', 'R', 'U', 'D', 'J', 'V', 'L', 'M', 'Y', 'F', 'T', 'G', 'W', 'W', 'H', 'P', 'T', 'U', 'D', 'I', 'A', 'H', 'W', 'R', 'M', 'S', 'X', 'X', 'A', 'H', 'J', 'D', 'N', 'B', 'R', 'H', 'Q', 'T', 'O', 'F', 'F', 'N', 'W', 'F', 'G', 'H', 'G', 'L', 'D', 'J', 'J', 'A', 'T', 'Q', 'W', 'H', 'U', 'E', 'Q', 'E', 'M', 'D', 'M', 'H', 'R', 'H', 'L', 'M', 'C', 'G', 'L', 'Z', 'A', 'Y', 'B', 'T', 'H', 'U', 'W', 'I', 'C', 'M', 'H', 'D', 'J', 'I', 'C', 'G', 'F', 'V', 'Z', 'T', 'J', 'H', 'W', 'R', 'F', 'Y', 'B', 'X', 'B', 'H', 'T', 'T', 'L', 'X', 'A', 'H', 'F', 'L', 'Y', 'M', 'H', 'D', 'K', 'M', 'Z', 'K', 'T', 'P', 'S', 'S', 'U', 'M', 'R', 'H', 'F', 'H', 'L', 'R', 'U', 'W', 'A', 'T', 'H', 'U', 'J', 'V', 'L', 'T', 'Q', 'L', 'Z', 'S', 'G', 'S', 'N', 'A', 'F', 'W', 'L', 'W', 'U', 'G', 'X', 'D', 'U', 'Y', 'C', 'H', 'S', 'W', 'Z', 'J', 'W', 'H', 'S', 'I', 'A', 'I', 'Y', 'G', 'Y', 'L', 'S', 'Q', 'C', 'M', 'D', 'D', 'F', 'I', 'M', 'X', 'H', 'X', 'J', 'N', 'N', 'R', 'Y', 'R', 'E', 'F', 'E', 'X', 'N', 'W', 'H', 'T', 'M', 'L', 'N', 'E', 'D', 'J', 'C', 'Y', 'D', 'R', 'M', 'H', 'I', 'G', 'X', 'L', 'V', 'J', 'L', 'X', 'Q', 'H', 'U', 'Y', 'L', 'H', 'S', 'L', 'U', 'Y', 'L', 'T', 'S', 'V', 'S', 'H', 'N', 'B', 'T', 'Q', 'K', 'F', 'H', 'W', 'T', 'Q', 'D', 'N', 'H', 'X', 'U', 'D', 'Q', 'R', 'Y', 'G', 'Y', 'V', 'S', 'Q', 'F', 'M', 'M', 'R', 'K', 'J', 'Q', 'H', 'Z', 'O', 'V', 'S', 'I', 'M', 'G', 'H', 'H', 'T', 'M', 'L', 'N', 'E', 'D', 'J', 'Q', 'B', 'Y', 'K', 'G', 'Z', 'N', 'X', 'S', 'F', 'J', 'D', 'J', 'M', 'N', 'R', 'F', 'X', 'U', 'B', 'I', 'G', 'J', 'R', 'U', 'K', 'P', 'P', 'S', 'S', 'O', 'E', 'N', 'V', 'S', 'X', 'Y', 'G', 'N', 'R', 'J', 'Q', 'Y', 'V', 'Y', 'X', 'J', 'J', 'L', 'B', 'S', 'F', 'J', 'D', 'J', 'M', 'T', 'J', 'J', 'F', 'J', 'A', 'D', 'D', 'L', 'Y', 'B', 'X', 'Z', 'Q', 'A', 'A', 'Y', 'K', 'X', 'L', 'L', 'D', 'I', 'Y', 'X', 'X', 'J', 'W', 'Y', 'R', 'F', 'W', 'A', 'Y', 'M', 'L', 'N', 'P', 'H', 'Q', 'Y', 'L', 'Y', 'H', 'F', 'H', 'L', 'R', 'U', 'W', 'A', 'T', 'H', 'B', 'X', 'D', 'D', 'Q', 'U', 'U', 'T', 'X', 'L', 'Y', 'L', 'T', 'S', 'V', 'X', 'T', 'L', 'F', 'N', 'Q', 'Y', 'N', 'H', 'M', 'J', 'O', 'D', 'N', 'A', 'B', 'G', 'O', 'W', 'S', 'O', 'F', 'G', 'H', 'J', 'X', 'I', 'K', 'Y', 'H', 'P', 'Y', 'M', 'H', 'Z', 'Q', 'V', 'X', 'U', 'G', 'I', 'L', 'E', 'F', 'A', 'X', 'X', 'L', 'F', 'Y', 'I', 'T', 'X', 'W', 'J', 'J', 'U', 'F', 'T', 'I', 'F', 'T', 'H', 'L', 'J', 'Q', 'K', 'J', 'N', 'A', 'J', 'U', 'W', 'F', 'L', 'X', 'R', 'D', 'F', 'D', 'G', 'T', 'S', 'B', 'O', 'F', 'S', 'L', 'Y', 'R', 'H', 'J', 'L', 'Y', 'T', 'U', 'E', 'Y', 'B', 'T', 'Y', 'W', 'J', 'F', 'H', 'L', 'K', 'R', 'J', 'R', 'U', 'M', 'N', 'R', 'F', 'X', 'I', 'F', 'J', 'V', 'L', 'W', 'U', 'B', 'L', 'K', 'L', 'K', 'I', 'K', 'B', 'D', 'J', 'I', 'U', 'G', 'I', 'V', 'G', 'R', 'Y', 'O', 'J', 'U', 'Q', 'H', 'I', 'F', 'U', 'O', 'W', 'C', 'G', 'H', 'X', 'W', 'A', 'S', 'P', 'H', 'Q', 'Y', 'W', 'X', 'Q', 'T', 'U', 'S', 'A', 'S', 'A', 'E', 'J', 'W', 'L', 'J', 'L', 'L', 'K', 'R', 'J', 'S', 'O', 'F', 'G', 'H', 'J', 'X', 'U', 'G', 'I', 'X', 'K', 'J', 'G', 'T', 'Y', 'K', 'K', 'Y', 'I', 'W', 'T', 'W', 'Z', 'J', 'N', 'K', 'F', 'Q', 'K', 'K', 'I', 'K', 'R', 'D', 'L', 'N', 'I', 'G', 'M', 'R', 'O', 'J', 'P', 'X', 'W', 'Q', 'G', 'R', 'U', 'M', 'Y', 'H', 'J', 'B', 'B', 'B', 'H', 'K', 'E', 'J', 'N', 'A', 'T', 'G', 'A', 'X', 'O', 'L', 'J', 'G', 'L', 'M', 'Y', 'K', 'J', 'V', 'M', 'Q', 'N', 'B', 'S', 'J', 'K', 'H', 'L', 'T', 'R', 'E', 'D', 'J', 'X', 'W', 'F', 'W', 'S', 'X', 'N', 'K', 'J', 'D', 'E', 'X', 'B', 'H', 'Z', 'O', 'V', 'L', 'C', 'O', 'J', 'Q', 'G', 'M', 'C', 'G', 'Y', 'V', 'S', 'G', 'I', 'N', 'Y', 'K', 'G', 'B', 'C', 'M', 'B', 'D', 'K', 'J', 'H', 'V', 'W', 'B', 'H', 'Y', 'Y', 'W', 'I', 'X', 'J', 'N', 'H', 'Z', 'B', 'R', 'J', 'Q', 'X', 'P', 'F', 'U', 'A', 'N', 'N', 'A', 'J', 'D', 'D', 'Q', 'C', 'X', 'X', 'V', 'U', 'T', 'L', 'X', 'I', 'V', 'G', 'R', 'Y', 'G', 'T', 'W', 'S', 'G', 'F', 'X', 'A', 'L', 'U', 'Y', 'I', 'K', 'N', 'H', 'K', 'F', 'A', 'T', 'N', 'Q', 'K', 'Y', 'N', 'A', 'J', 'J', 'W', 'W', 'G', 'T', 'S', 'V', 'T', 'J', 'W', 'T', 'Z', 'V', 'W', 'Y', 'B', 'X', 'N', 'U', 'W', 'S', 'W', 'K', 'D', 'S', 'L', 'N', 'I', 'G', 'X', 'B', 'K', 'Y', 'Y', 'F', 'X', 'G', 'A', 'I', 'H', 'H', 'Y', 'V', 'M', 'K', 'Z', 'B', 'H', 'L', 'W', 'S', 'N', 'E', 'D', 'V', 'U', 'W', 'U', 'F', 'G', 'O', 'W', 'R', 'Y', 'L', 'X', 'D', 'Y', 'J', 'M', 'K', 'N', 'J', 'G', 'W', 'I', 'N', 'X', 'P', 'S', 'Y', 'B', 'X', 'R', 'D', 'L', 'N', 'W', 'T', 'Q', 'D', 'F', 'F', 'F', 'R', 'X', 'L', 'K', 'G', 'S', 'T', 'Q', 'O', 'A', 'J', 'X', 'V', 'T', 'G', 'W', 'H', 'L', 'T', 'H', 'N', 'W', 'W', 'M', 'E', 'F', 'L', 'V', 'G', 'U', 'K', 'J', 'S', 'S', 'Y', 'N', 'X', 'W', 'Q', 'K', 'M', 'C', 'W', 'I', 'H', 'F', 'B', 'C', 'M', 'M', 'L', 'F', 'Y', 'B', 'X', 'R', 'H', 'K', 'X', 'U', 'Z', 'J', 'V', 'S', 'S', 'X', 'N', 'X', 'H', 'V', 'Y', 'B', 'X', 'R', 'W', 'G', 'W', 'Y', 'V', 'W', 'H', 'S', 'Y', 'Y', 'M', 'M', 'H', 'E', 'F', 'W', 'A', 'N', 'Q', 'W', 'Z', 'M', 'X', 'I', 'W', 'G', 'J', 'H', 'V', 'W', 'B', 'H', 'Y', 'N', 'A', 'J', 'P', 'L', 'M', 'I', 'L', 'J', 'F', 'G', 'I', 'Y', 'L', 'W', 'H', 'N', 'T', 'F', 'O', 'J', 'G', 'S', 'W', 'I', 'N', 'S', 'G', 'L', 'M', 'Y', 'N', 'X', 'H', 'G', 'K', 'M', 'X', 'H', 'U', 'W', 'Y', 'E', 'X', 'D', 'V', 'L', 'M', 'U', 'M', 'B', 'H', 'J', 'J', 'M', 'A', 'F', 'U', 'W', 'I', 'U', 'F', 'T', 'Q', 'Y', 'Y', 'B', 'H', 'X', 'H', 'O', 'M', 'I', 'G', 'J', 'H', 'V', 'J', 'X', 'M', 'T', 'F', 'G', 'R', 'G', 'N', 'S', 'L', 'U', 'F', 'N', 'X', 'X', 'H', 'U', 'Z', 'L', 'X', 'Q', 'B', 'L', 'M', 'Y', 'L', 'J', 'D', 'J', 'J', 'E', 'G', 'T', 'Z', 'F', 'F', 'M', 'L', 'D', 'P', 'E', 'J', 'N', 'K', 'N', 'F', 'W', 'S', 'W', 'K', 'D', 'S', 'L', 'N', 'I', 'G', 'X', 'B', 'K', 'Y', 'Y', 'F', 'X', 'D', 'F', 'I', 'B', 'T', 'A', 'H', 'S', 'B', 'Y', 'T', 'P', 'Q', 'W', 'X', 'M', 'B', 'S', 'W', 'Z', 'F', 'N', 'X', 'A', 'H', 'J', 'D', 'I', 'G', 'J', 'L', 'F', 'A', 'I', 'E', 'A', 'H', 'V', 'M', 'U', 'L', 'Y', 'R', 'H', 'T', 'M', 'L', 'J', 'V', 'K', 'Y', 'B', 'X', 'X', 'D', 'E', 'J', 'M', 'X', 'Y', 'R', 'X', 'X', 'Y', 'V', 'W', 'H', 'L', 'P', 'Y', 'R', 'X'], 'SECRET')
encryptionmakesthemodernworldgoroundeverytimeyoumakeamobilephonecallbuysomethingwithacreditcardinashoporontheweborevengetcashfromanatmencryptionbestowsuponthattransactiontheconfidentialityandsecuritytomakeitpossibleifyouconsiderelectronictransactionsandonlinepaymentsallthosewouldnotbepossiblewithoutencryptionsaiddrmarkmanulisaseniorlecturerincryptographyattheuniversityofsurreyatitssimplestencryptionisallabouttransformingintelligiblenumbersortextsoundsandimagesintoastreamofnonsensetherearemanymanywaystoperformthattransformationsomestraightforwardandsomeverycomplexmostinvolveswappinglettersfornumbersandusemathstodothetransformationhowevernomatterwhichmethodisusedtheresultingscrambleddatastreamshouldgivenohintsabouthowitwasencryptedduringworldwariithealliesscoredsomenotablevictoriesagainstthegermansbecausetheirencryptionsystemsdidnotsufficientlyscramblemessagesrigorousmathematicalanalysisbyalliedcodecrackerslaidbarepatternshiddenwithinthemessagesandusedthemtorecreatethemachineusedtoencryptthemthosecodesrevolvedaroundtheuseofsecretkeysthatweresharedamongthosewhoneededtocommunicatesecurelytheseareknownassymmetricencryptionsystemsandhaveaweaknessinthateveryoneinvolvedhastopossessthesamesetofsecretkeys
"""
keyString = keyString.upper()
keyLength = len(keyString)
decryptedCharList = []
subKeyIndex = 0
for char in charList:
subKeyLetter = keyString[subKeyIndex]
subKey = cipher_utils.cipherLetterToOrdinal(subKeyLetter) + 1
cipherOrdinal = cipher_utils.cipherLetterToOrdinal(char)
plainTextOrdinal = (cipherOrdinal - subKey) % 26
plainTextLetter = cipher_utils.ordinalToClearLetter(plainTextOrdinal)
decryptedCharList.append(plainTextLetter)
subKeyIndex += 1
logger.debug(
'SubKey %s (%s - %s):\tcipher char: %s (%s)\tplaintext char: %s (%s)'
% (subKeyIndex, subKey, subKeyLetter, char, cipherOrdinal + 1,
plainTextLetter, plainTextOrdinal + 1))
if subKeyIndex == keyLength:
subKeyIndex = 0
return ''.join(decryptedCharList)
def matrixMult(keyMatrix, colVector):
m = n = len(keyMatrix)
letterBlock = []
for i in range(n):
productElement = 0
for j in range(m):
keyLetter = keyMatrix[i][j]
keyOrd = cipher_utils.cipherLetterToOrdinal(keyLetter)
letter = colVector[j]
letterOrd = cipher_utils.cipherLetterToOrdinal(letter)
productElement += keyOrd * letterOrd
cipherOrd = (productElement) % 26
cipherLetter = cipher_utils.integerToChr(cipherOrd)
logger.debug(
'%s (%s) x %s (%s) = %s (%s)' %
(keyLetter, keyOrd, letter, letterOrd, cipherOrd, cipherLetter))
letterBlock.append(cipherLetter)
return ''.join(letterBlock)
def deriveVigenereKeyPhraseFromCrib(cipherChars, crib):
# Derive a possible Vigenere keyphrase from the most frequently occurring letter for each sub key
""" (str, str) -> str
Derive a possible Vigenere keyphrase from a section of the cipher, with a guessed crib
>>> deriveVigenereKeyPhrase('HTPEG', 'MARTIN')
'MARTIN'
"""
keyPhrase = []
index = 0
for cipherChar in cipherChars:
cipherCharOrdinal = cipher_utils.cipherLetterToOrdinal(cipherChar)
caesarShift = (cipherCharOrdinal - cipher_utils.cipherLetterToOrdinal(
crib[index]) - 1) % 26
keyChar = cipher_utils.ordinalToClearLetter(caesarShift).upper()
keyPhrase.append(keyChar)
logger.info(
'Cipher character %s (%s) should be %s (%s),\tCaesar Shift for sub key = %s,\tkeyChar = %s'
%
(cipherChar, cipherCharOrdinal + 1, crib[index],
cipherLetterToOrdinal(crib[index]) + 1, caesarShift + 1, keyChar))
index += 1
return ''.join(keyPhrase)
def deriveVigenereKeyPhrase(frequentChars):
# Derive a possible Vigenere keyphrase from the most frequently occurring letter for each sub key
""" (str) -> str
Derive a possible Vigenere keyphrase from the most frequently occurring letter for each sub key
Please note, the key length should be known, or at least correctly guessed, for this function
to produce meaningful results.
>>> deriveVigenereKeyPhrase('XJHJDY')
'SECRET'
"""
keyPhrase = []
for frequentChar in frequentChars:
frequentCharOrdinal = cipher_utils.cipherLetterToOrdinal(frequentChar)
caesarShift = (frequentCharOrdinal - 5) % 26 # 'E' = 5
keyChar = cipher_utils.ordinalToClearLetter(caesarShift).upper()
keyPhrase.append(keyChar)
logger.info(
'Frequent character %s (%s) should be E (5),\tCaesar Shift for sub key = %s,\tkeyChar = %s'
%
(frequentChar, frequentCharOrdinal + 1, caesarShift + 1, keyChar))
return ''.join(keyPhrase)
def decryptSimpleSubstitutionCipher(charList, keyString, dummy=None):
""" (list, str, str) -> str
Decrypt the passed ciphertext list charList, encrypted with simple substitution cipher
using the passed key keyString. Dummy characters are defined by the argument dummy,
which, if set, will simply display the ciphertext character
>>> decryptSimpleSubstitutionCipher(['A', 'B', 'C', ' ', 'Z'], 'KEYABCDFGHIJLMNOPQRSTUVWX.', dummy='.')
'key Z'
"""
decryptedCharList = []
logger.debug('Cipher\tPlain')
for char in charList:
cipherOrdinal = cipher_utils.cipherLetterToOrdinal(char)
if cipherOrdinal in range(len(keyString)):
plainTextLetter = keyString[cipherOrdinal].lower()
if plainTextLetter == dummy:
plainTextLetter = char
else:
plainTextLetter = char
decryptedCharList.append(plainTextLetter)
logger.debug('%s\t%s' % (char, plainTextLetter))
return ''.join(decryptedCharList)
def getMatrixInverse(keyMatrix):
# calc inv matrix
# Only proven to work on a 2x2 matrix (4 letter keyword) for now
# First, find the determinant det K of keyMatrix K
det = 0
m = n = p = len(keyMatrix)
for i in range(m // 2):
for j in range(n):
subDet = cipher_utils.cipherLetterToOrdinal(
keyMatrix[i][j]) * cipher_utils.cipherLetterToOrdinal(
keyMatrix[m - 1][n - 1])
if i == j:
det += subDet
else:
det -= subDet
logger.debug(
'determinant=%s, i=%s, j=%s, m=%s, n=%s, keyL=%s, keyR=%s' %
(det, i, j, m, n,
cipher_utils.cipherLetterToOrdinal(keyMatrix[i][j]),
cipher_utils.cipherLetterToOrdinal(keyMatrix[m - 1][n - 1])))
n -= 1
n = p
m -= 1
det = det % 26
logger.debug('determinant = %s' % (det))
# Next, find the multiplicative inverse of the determinant det K
di = 0
for x in range(26):
if (det * x) % 26 == 1:
di = x
if di == 0:
print('could not invert, try different key')
return None
logger.debug(
'multiplicative inverse K**-1 of the determinant det K (such that (det * x) mod 26 = 1 : %s'
% (di))
keyInverseMatrix = []
m = n = p = len(keyMatrix)
for i in range(p):
row = []
for j in range(p):
if i == j:
inverse = di * cipher_utils.cipherLetterToOrdinal(
keyMatrix[m - 1][n - 1])
logger.debug('m=%s, n=%s row[%s][%s] = %s (mod 26)' %
(m - 1, n - 1, i, j, inverse))
else:
inverse = -1 * di * cipher_utils.cipherLetterToOrdinal(
keyMatrix[i][j])
logger.debug('i=%s, j=%s row[%s][%s] = %s (mod 26)' %
(i, j, i, j, inverse))
inverse = inverse % 26
row.append(inverse)
logger.debug('row[%s][%s] = %s' % (i, j, inverse))
n -= 1
keyInverseMatrix.append(row)
n = p
m -= 1
logger.debug('keyInverseMatrix = %s' % (keyInverseMatrix))
return keyInverseMatrix