def is_padding(the_string, block_size):
hx = the_string.encode("hex")
hx = rypto.split(hx, 2)
last = hx[-1] #Last byte in string
num_bytes = int(last, 16)
if num_bytes == 1:
block_size_check(the_string,
block_size) #Checks to make sure valid to block size
print 'Assuming it is ACTUALLY only padded with one byte:' #If it made it past block size check
return rypto.unpad(the_string, block_size)
else:
try:
same_byte_check(
hx, num_bytes
) #Checks for ending in correct number of bytes and the same byte
block_size_check(
the_string, block_size
) #Checks again blocksize with default padding function
return rypto.unpad(
the_string, block_size
) #Returns block size with assumption it made it this far without errors
except ValueError as e:
raise
def prep_cbc(s, k, iv, bs):
final = ''
#Splits into 16 byte blocks
s = rypto.split(s, 32)
#Converts to ascii, kinda. Just required of AES function.
k = k.decode("hex")
#Inserts iv to the beginning of the block for the for loop
s.insert(0, iv)
#Cycle through all blocks
for i in range(1, len(s)):
x = cbc_decrypt(s[i], k, s[i - 1]) #Decrypts and sends iv as s[i-1]
final += x.decode("hex") #Decodes reponse
return rypto.unpad(final, bs) #Unpads and returns
if rem == 0:
blocks = value
else:
blocks = value + 1
return blocks
if __name__ == "__main__":
message = open("w8.txt").readlines()
for l, q in enumerate(message):
sentence = ''
q = q.decode("base64")
webapp = rypto.webapp() #encryption class (oracle)
enc = webapp.encrypt(q) #encrypted value
num_blocks = num_of_blocks(enc)
for m in range(0, num_blocks): #For every block (after 0)
try:
sentence += single_block(enc, m) #Check for one block
except ValueError as e:
print "I guess were skipping this one"
print 'Message', l
try:
print rypto.unpad(sentence, 128)
except ValueError as e:
print sentence
def block_size_check(b_string, block_size):
try:
rypto.unpad(b_string, block_size)
except Exception:
raise ValueError('The padding bytes do not match the block size')