Encryption algorithm randomly replaces some letters

Question

I have the following python code:

file = open("encryption.txt","r")

str1 = file.read()

file.close
charList = []
for char in str1:
    charList.append(char)

bits = []
ascList = []
for i in range(len(charList)):
    ascList.append(ord(charList[i]))
    ascList[i] = "{0:08b}".format(ascList[i])
    currentAsc = ascList[i]
    currentStr = str(currentAsc)
    for x in range(len(currentStr)):

        currentChar = currentStr[x]
        bits.append(int(currentChar))

keyChar = input("enter the character that should act as the key: ")
keyAsc = "{0:08b}".format(ord(keyChar))
keyStr = str(keyAsc)
keyBits = []
for x in range(len(keyStr)):
    keyBits.append(int(keyStr[x]))


key = []
while len(key) != len(bits):

    for i in range(len(keyBits)):
        key.append(keyBits[i])


resultBits = []
for i in range(len(bits)):
    if key[i] != bits[i]:
        resultBits.append("1")
    else:
        resultBits.append("0")

resultSplitInt = []
resultInt = ''.join(resultBits)
for i in range(0,len(resultInt), 8):
    resultSplitInt.append(resultInt[i:i+8])

resultSplit = []
for i in range(len(resultSplitInt)):
    resultSplit.append(chr(int(resultSplitInt[i],2)))

result = ''.join(resultSplit)

file = open("encryption.txt","w")
print(str1)
print("--------------------")
print(result)
file.write(result)
print("done")
file.close()

running the program once should change the contents of "encryption.txt" based on the key, and running the program again should return the contents to their original form.

however, when I actually run the code, some letters are swapped out.

for example: if the contents are "hello world" and I use the key "a" after running the code twice I am left with "hekko workd"

why does this happen, and how can I fix it?

p.s. I am aware that this is neither a secure encryption algorithm nor is my code very efficient. I am new to python and thought this would be a fun task to try. I got this far and can't find any reasons why it isn't working

I can't reproduce that; I get "A" as output. But maybe the problem is that you aren't properly closing the file: `file.close` should be `file.close()`. — Aran-Fey, Nov 03 '18 at 15:46

score 0 · Answer 1 · answered Nov 03 '18 at 15:52

0

Close the file;

file = open("encryption.txt","r")

str1 = file.read()

file.close()

Then it works.

By the way, at least use 'a'='A'

answered Nov 03 '18 at 15:52

kelalaka

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score 0 · Accepted Answer · answered Nov 03 '18 at 21:58

Since you operate outside ASCII range, you should open the file in binary mode: open("encryption.txt","rb") and open("encryption.txt","wb")

However, in binary mode you get a byte array from the file, not a string:

file = open("encryption.txt","rb")

str1 = file.read()

file.close()
charList = []
for char in str1:
    charList.append(char)

bits = []
ascList = []
for i in range(len(charList)):
    ascList.append(charList[i])
    ascList[i] = "{0:08b}".format(ascList[i])
    currentAsc = ascList[i]
    currentStr = str(currentAsc)
    for x in range(len(currentStr)):

        currentChar = currentStr[x]
        bits.append(int(currentChar))

keyChar = input("enter the character that should act as the key: ")
keyAsc = "{0:08b}".format(ord(keyChar))
keyStr = str(keyAsc)
keyBits = []
for x in range(len(keyStr)):
    keyBits.append(int(keyStr[x]))


key = []
while len(key) != len(bits):

    for i in range(len(keyBits)):
        key.append(keyBits[i])


resultBits = []
for i in range(len(bits)):
    if key[i] != bits[i]:
        resultBits.append("1")
    else:
        resultBits.append("0")

resultSplitInt = []
resultInt = ''.join(resultBits)
for i in range(0,len(resultInt), 8):
    resultSplitInt.append(resultInt[i:i+8])

resultSplit = []
for i in range(len(resultSplitInt)):
    resultSplit.append(chr(int(resultSplitInt[i],2)))

result = ''.join(resultSplit)

file = open("encryption.txt","wb")
print(str1)
print("--------------------")
print(result)
file.write(result.encode())
print("done")
file.close()

Encryption algorithm randomly replaces some letters

2 Answers2