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decFuncs.py
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decFuncs.py
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from Funcs import *
from encFuncs import *
def clearHexPadding(inValue):
if (inValue[-2:] in ['00', '01', '02', '03', '04', '05', '06', '07', '08', '09', '0a', '0b', '0c', '0d', '0e', '0f', '10']):
return clearHexPadding(inValue[:-2])
else:
return inValue
def lookupInvSBox(inValue):
invSBox = [
0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d
]
res = []
for i in range(len(inValue)):
res.append(hex(invSBox[int(inValue[i], base=16)]))
return res
def prepend0x(inValue):
return("0x" + inValue)
def initDecRound(inValue, key):
inValue = transposeMtrx(addRoundKey((inValue), mtrx4x4((key))))
val2 = [rotRowLeft(inValue[i], -1*i) for i in range(4)]
res = []
for i in range(len(val2)):
res.append(lookupInvSBox(val2[i]))
return(transposeMtrx(res))
def invSubBytes(inValue):
invSubbedBytes = []
for k in range(len(inValue)):
invSubbedBytes += lookupInvSBox(inValue[k])
return transposeMtrx(mtrx4x4(invSubbedBytes))
def decRound(inValue, roundKeys):
for i in range(len(roundKeys)-2, 0, -1):
inValue = transposeMtrx(mixCols(mixCols(mixCols(
addRoundKey(inValue, mtrx4x4(roundKeys[i]))))))
inValue = [rotRowLeft(inValue[j], -1*j) for j in range(4)]
inValue = invSubBytes(inValue)
return inValue
def finalDecRound(inValue, key):
return(addRoundKey((inValue), mtrx4x4((key))))
def decBlock(block, roundKeys):
return finalDecRound(decRound(initDecRound(
block, roundKeys[-1]), roundKeys), roundKeys[0])
def prepDecBytes(inValue):
inValue = divInBlocks(inValue, 2)
res = []
for block in inValue:
res.append(prepend0x(block))
return divInBlocks(mtrx4x4(res), 4)
def decOFB(inValue, roundKeys, iv):
res = []
res.append(encOFB(divInBlocks(nestedToSingleList(
inValue), 16), iv, roundKeys))
return res
def decCFB(inValue, roundKeys, iv):
res = []
oldIV = []
for block in inValue:
if oldIV != []:
iv = oldIV[-4:]
encIV = encBlock(iv, roundKeys)
for blockIdx, block4x4 in enumerate(block):
Plaintxt = xorMatrices([block4x4], [encIV[blockIdx]])
oldIV.append(block4x4)
res.extend(Plaintxt)
return res
def decCTR(inValue, roundKeys, iv):
res = []
res.append(encCTR(divInBlocks(nestedToSingleList(
inValue), 16), iv, roundKeys))
return res
def decCBC(inValue, roundKeys, iv):
res = []
for block in inValue:
plainText = decBlock(block, roundKeys)
plainText = xorMatrices(plainText, iv)
iv = block
res.append(plainText)
return res
def decECB(inValue, roundKeys):
res = []
for block in inValue:
res.append(decBlock(block, roundKeys))
return res
def decrypt(inValue, secretKey, rounds, mode="ECB", iv=None):
res = []
if mode != "ECB":
iv = mtrx4x4(strToHex(iv))
inValue = prepDecBytes(inValue)
roundKeys = genRoundKeys(strToHex(secretKey), rounds)
if(mode == "CFB"):
res.append(decCFB(inValue, roundKeys, iv))
elif(mode == "OFB"):
res.append(decOFB(inValue, roundKeys, iv))
elif(mode == "CTR"):
res.append(decCTR(inValue, roundKeys, iv))
elif(mode == "CBC"):
res.append(decCBC(inValue, roundKeys, iv))
elif(mode == "ECB"):
res.append(decECB(inValue, roundKeys))
return res