def recoverBytes():
# first, determine number of bytes needed to push prefix up to a block boundry
# and where the first block fully controlled by my input lies (effectively, determine prefix length)
numBytesForPrefix, firstControlledBlock = determinePrefixLength()
# deterine target plaintext length
targetPlaintextLength = prob14DeterminePlaintextLength() + (
numBytesForPrefix) - (firstControlledBlock * 16)
# do the problem 12 process
knownPlaintext = b''
blockSize = 16
for i in range(targetPlaintextLength):
# Set first unknown byte to be last byte in block
padLen = numBytesForPrefix + (blockSize - 1) - (len(knownPlaintext) %
blockSize)
pad = padStr * padLen
# Collect cipher, identify cipher blocks of interest
cipherOutput = prob14Encrypt(pad)
blockOfInterest = firstControlledBlock + (len(knownPlaintext) // 16)
cipherChunks = chunks(cipherOutput, blockSize)
cipherOfInterest = cipherChunks[blockOfInterest]
###knownPlainChunks.append(b'');
# prefix is last 15 bytes of (pad|knownPlaintext)
prefix = (pad + knownPlaintext)[-15:]
knownPlaintext += prob14DetermineNextByte(prefix, cipherOfInterest,
numBytesForPrefix,
firstControlledBlock)
return knownPlaintext
def detectMode():
plaintext = b'A' * 48;
cipher = append_and_encrypt(plaintext);
blocks = chunks(cipher, 16);
if (blocks[1] == blocks[2]):
return "ECB";
else:
return "NOT ECB";
def detectMode():
plaintext = b'A' * 48; #ensure that 2nd, 3rd blocks of cipher have same plaintext
cipher = encryption_oracle(plaintext);
blocks = chunks(cipher, 16);
if (blocks[1] == blocks[2]):
print("ECB");
else:
print("CBC");
def aes_ctr(rawInput, rawKey, rawIV):
inputBlocks = chunks(rawInput, 16);
rawOutput = b'';
for block in inputBlocks:
keyStream = aes_ecb_enc(rawIV, rawKey);
rawOutput += raw_xor(keyStream, block);
rawIV = incrementIV(rawIV);
return rawOutput;
def detectMode():
plaintext = b'A' * 48
cipher = append_and_encrypt(plaintext)
blocks = chunks(cipher, 16)
if (blocks[1] == blocks[2]):
return "ECB"
else:
return "NOT ECB"
def recoverPlaintext():
targetCipher, iv = encryptString();
targetBlocks = chunks(targetCipher, 16);
plaintext = b'';
for i in range(len(targetBlocks)):
plaintext += recoverBlock(targetBlocks[i], iv);
iv = targetBlocks[i];
return plaintext;
def aes_ctr(rawInput, rawKey, rawIV):
inputBlocks = chunks(rawInput, 16)
rawOutput = b''
for block in inputBlocks:
keyStream = aes_ecb_enc(rawIV, rawKey)
rawOutput += raw_xor(keyStream, block)
rawIV = incrementIV(rawIV)
return rawOutput
def aes_cbc_dec(rawCipher, rawKey, rawIV):
cipherBlocks = chunks(rawCipher, 16);
plain = b'';
for block in cipherBlocks:
ecbOut = aes_ecb_dec(block, rawKey);
cbcOut = hexToRaw(hex_xor(rawToHex(ecbOut), rawToHex(rawIV)));
rawIV = block;
plain += cbcOut;
return plain;
def aes_cbc_enc(rawPlain, rawKey, rawIV):
plainBlocks = chunks(rawPlain, 16);
cipher = b'';
for block in plainBlocks:
blockIn = hexToRaw(hex_xor(rawToHex(block), rawToHex(rawIV)));
blockOut = aes_ecb_enc(blockIn, rawKey);
rawIV = blockOut;
cipher += blockOut;
return cipher;
def detectMode():
plaintext = b'A' * 48
#ensure that 2nd, 3rd blocks of cipher have same plaintext
cipher = encryption_oracle(plaintext)
blocks = chunks(cipher, 16)
if (blocks[1] == blocks[2]):
print("ECB")
else:
print("CBC")
def aes_cbc_dec(rawCipher, rawKey, rawIV):
cipherBlocks = chunks(rawCipher, 16)
plain = b""
for block in cipherBlocks:
ecbOut = aes_ecb_dec(block, rawKey)
cbcOut = hexToRaw(hex_xor(rawToHex(ecbOut), rawToHex(rawIV)))
rawIV = block
plain += cbcOut
return plain
def aes_cbc_dec(rawCipher, rawKey, rawIV):
cipherBlocks = chunks(rawCipher, 16)
plain = b''
for block in cipherBlocks:
ecbOut = aes_ecb_dec(block, rawKey)
cbcOut = hexToRaw(hex_xor(rawToHex(ecbOut), rawToHex(rawIV)))
rawIV = block
plain += cbcOut
return plain
def aes_cbc_enc(rawPlain, rawKey, rawIV):
plainBlocks = chunks(rawPlain, 16)
cipher = b""
for block in plainBlocks:
blockIn = hexToRaw(hex_xor(rawToHex(block), rawToHex(rawIV)))
blockOut = aes_ecb_enc(blockIn, rawKey)
rawIV = blockOut
cipher += blockOut
return cipher
def aes_cbc_enc(rawPlain, rawKey, rawIV):
plainBlocks = chunks(rawPlain, 16)
cipher = b''
for block in plainBlocks:
blockIn = hexToRaw(hex_xor(rawToHex(block), rawToHex(rawIV)))
blockOut = aes_ecb_enc(blockIn, rawKey)
rawIV = blockOut
cipher += blockOut
return cipher
def determinePrefixLength():
plainLength = 32
while (True):
plain = b'A' * plainLength
cipher = prob14Encrypt(plain)
cipherBlocks = chunks(cipher, 16)
for i in range(len(cipherBlocks) - 1):
if (cipherBlocks[i] == cipherBlocks[i + 1]):
return (len(plain) % 16), i
plainLength += 1
def determinePrefixLength():
plainLength = 32;
while (True):
plain = b'A' * plainLength;
cipher = prob14Encrypt(plain);
cipherBlocks = chunks(cipher, 16);
for i in range(len(cipherBlocks)-1):
if (cipherBlocks[i] == cipherBlocks[i+1]):
return (len(plain)%16), i;
plainLength += 1;
def prob14DetermineNextByte(rawPrefix, observedCipher, numBytesForPrefix, firstControlledBlock):
blockSize = 16;
plain = (padStr) * (numBytesForPrefix + blockSize - 1 - len(rawPrefix));
plain += rawPrefix;
for i in range(256):
thisPlain = plain + bytes(chr(i), 'UTF-8');
thisCipher = prob14Encrypt(thisPlain);
if (chunks(thisCipher, blockSize)[firstControlledBlock] == observedCipher):
return bytes(chr(i), 'UTF-8');
return b'***ERROR***';
def prob14DetermineNextByte(rawPrefix, observedCipher, numBytesForPrefix,
firstControlledBlock):
blockSize = 16
plain = (padStr) * (numBytesForPrefix + blockSize - 1 - len(rawPrefix))
plain += rawPrefix
for i in range(256):
thisPlain = plain + bytes(chr(i), 'UTF-8')
thisCipher = prob14Encrypt(thisPlain)
if (chunks(thisCipher,
blockSize)[firstControlledBlock] == observedCipher):
return bytes(chr(i), 'UTF-8')
return b'***ERROR***'
def determineNextByte(rawPrefix, observedCipher):
''' Given a prefix, generates 256 blocks of the form:
AA..AA|prefix|?, and checks for a match against the observed cipher
'''
blockSize = determineBlockSize()
plain = (padStr) * (blockSize - 1 - len(rawPrefix))
plain += rawPrefix
for i in range(256):
thisPlain = plain + bytes(chr(i), 'UTF-8')
thisCipher = append_and_encrypt(thisPlain)
if (chunks(thisCipher, blockSize)[0] == observedCipher):
return bytes(chr(i), 'UTF-8')
return b'***ERROR***'
def determineNextByte(rawPrefix, observedCipher):
''' Given a prefix, generates 256 blocks of the form:
AA..AA|prefix|?, and checks for a match against the observed cipher
'''
blockSize = determineBlockSize()
plain = (padStr) * (blockSize - 1 - len(rawPrefix));
plain += rawPrefix;
for i in range(256):
thisPlain = plain + bytes(chr(i), 'UTF-8');
thisCipher = append_and_encrypt(thisPlain);
if (chunks(thisCipher, blockSize)[0] == observedCipher):
return bytes(chr(i), 'UTF-8');
return b'***ERROR***';
def determinePlaintext():
blockSize = determineBlockSize()
plaintextLength = determinePlaintextLength();
knownPlaintext = b'';
for i in range(plaintextLength):
# Set first unknown byte to be last byte in block
padLen = (blockSize - 1) - (len(knownPlaintext) % blockSize);
pad = padStr * padLen;
# Collect cipher, identify cipher blocks of interest
cipherOutput = append_and_encrypt(pad);
blockOfInterest = len(knownPlaintext) // 16;
cipherChunks = chunks(cipherOutput, blockSize);
cipherOfInterest = cipherChunks[blockOfInterest];
###knownPlainChunks.append(b'');
# prefix is last 15 bytes of (pad|knownPlaintext)
prefix = (pad + knownPlaintext)[-15:];
knownPlaintext += determineNextByte(prefix, cipherOfInterest);
return knownPlaintext;
def determinePlaintext():
blockSize = determineBlockSize()
plaintextLength = determinePlaintextLength()
knownPlaintext = b''
for i in range(plaintextLength):
# Set first unknown byte to be last byte in block
padLen = (blockSize - 1) - (len(knownPlaintext) % blockSize)
pad = padStr * padLen
# Collect cipher, identify cipher blocks of interest
cipherOutput = append_and_encrypt(pad)
blockOfInterest = len(knownPlaintext) // 16
cipherChunks = chunks(cipherOutput, blockSize)
cipherOfInterest = cipherChunks[blockOfInterest]
###knownPlainChunks.append(b'');
# prefix is last 15 bytes of (pad|knownPlaintext)
prefix = (pad + knownPlaintext)[-15:]
knownPlaintext += determineNextByte(prefix, cipherOfInterest)
return knownPlaintext
def recoverBytes():
# first, determine number of bytes needed to push prefix up to a block boundry
# and where the first block fully controlled by my input lies (effectively, determine prefix length)
numBytesForPrefix, firstControlledBlock = determinePrefixLength();
# deterine target plaintext length
targetPlaintextLength = prob14DeterminePlaintextLength() + (numBytesForPrefix) - (firstControlledBlock * 16);
# do the problem 12 process
knownPlaintext = b'';
blockSize = 16;
for i in range(targetPlaintextLength):
# Set first unknown byte to be last byte in block
padLen = numBytesForPrefix + (blockSize - 1) - (len(knownPlaintext) % blockSize);
pad = padStr * padLen;
# Collect cipher, identify cipher blocks of interest
cipherOutput = prob14Encrypt(pad);
blockOfInterest = firstControlledBlock + (len(knownPlaintext) // 16);
cipherChunks = chunks(cipherOutput, blockSize);
cipherOfInterest = cipherChunks[blockOfInterest];
###knownPlainChunks.append(b'');
# prefix is last 15 bytes of (pad|knownPlaintext)
prefix = (pad + knownPlaintext)[-15:];
knownPlaintext += prob14DetermineNextByte(prefix, cipherOfInterest, numBytesForPrefix, firstControlledBlock);
return knownPlaintext;
def generateEncryptedAdminProfile():
# get to a fresh block
s = 'A' * (16 - (len(prefix) % 16));
#locate the IV for my block
myIVBlock = ((len(prefix) + len(s)) // 16) - 1;
# add a known block value
s += 'X' * 16;
# encrypt
cip = padAndEncryptString(s);
# extract IV for block of interest
allBlocks = chunks(cip, 16);
myIV = allBlocks[myIVBlock];
# xor in IV with desired value
hexIV = rawToHex(myIV);
hexKnown = rawToHex('X'*16);
hexDesired = rawToHex(";admin=true;XXXX")
newHexIV = hex_xor(hexIV, hex_xor(hexKnown, hexDesired));
newIV = hexToRaw(newHexIV);
# insert "error"
allBlocks[myIVBlock] = newIV;
myCipher = b'';
for b in allBlocks:
myCipher += b;
return myCipher;