Recursively repeating each combination of characters
Expected Result:
The program accepts a hashed password as input; this is passed to the decryption function. The function iterates over each mixed n-letter combination, hashing each such string. If it finds a match with the input, it prints the un-hashed password; otherwise it will exit.
Actual result:
The function iterates over each letter of the mixed case for only the last letter in the current iteration.
Description of the problem:
I am trying to implement a simple password cracked password cracked in Python. I made an implementation for 4 character passwords using lots of loops, but now I want to refactor them for a range of lengths using recursion. How can I iterate over each combination of characters, starting with a combination of 1 char to a 4-character combination of strings?
I wanted to use this line:
password[i] = string.ascii_letters[j]
But I am getting this error:
TypeError: 'str' object does not support item assignment
Snippet of code:
def decrypt(encryptedText):
# reference global variable
global password
# check curr password guess length
pwdlen = len(password)
if pwdlen >= 4:
print("Password is longer than 4 characters, exiting...")
exit(2)
# debug lines
print("password is {}".format(password))
print("length: {}".format(pwdlen))
time.sleep(2)
# first two characters is salt
salt = encryptedText[:2]
# Check hashes for every combination of strings and compare them
# starts with last char
for i in range(pwdlen, 0, -1):
for j in range(0, len(string.ascii_letters)):
password = string.ascii_letters[:pwdlen] + string.ascii_letters[j]
hashed = crypt.crypt(password, salt)
# debug line
print(password)
# if found - print password and exit
if hashed == encryptedText:
print(password)
exit(0)
# this makes recursion go through +1 char combinations on every iteration
password = (pwdlen + 1) * 'a'
return decrypt(encryptedText)
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Strings are immutable. You cannot assign a new value to part of a string. Instead, you need to create a new value and assign it to the original variable. For example:
# password[i] = string.ascii_letters[j]
password = password[:i] + string.ascii_letters[j] + password[i+1:]
Second, you can probably do much better using itertools to generate any permutations you need. For example, generate the product asci_letters as many times as you like and join these sequences of letters.
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