将数字转换为字母中的相应字母-Python 2.7

Question

I am currently working on a python project to take a string of text, encrypt the text by adding a keyword to it and then outputting the result. I currently have all the features of this program operational except converting the numerical value back into text.

For example, the raw text will be converted into a numerical value, for instance [a, b, c] will become [1, 2, 3] .

Currently I have no ideas of how to correct this issue and would welcome any help, my current code is as follows:

def encryption():
    print("You have chosen Encryption")
    outputkeyword = []
    output = []

    input = raw_input('Enter Text: ')
    input = input.lower()

    for character in input:
        number = ord(character) - 96
        output.append(number)

    input = raw_input('Enter Keyword: ')
    input = input.lower()
    for characterkeyword in input:
        numberkeyword = ord(characterkeyword) - 96
        outputkeyword.append(numberkeyword)
        first = output
        second = outputkeyword

    print("The following is for debugging only")
    print output
    print outputkeyword

    outputfinal = [x + y for x, y in zip(first, second)]
    print outputfinal

def decryption():
    print("You have chosen Decryption")
    outputkeyword = []
    output = []
    input = raw_input('Enter Text: ')
    input = input.lower()
    for character in input:
        number = ord(character) - 96
        output.append(number)

    input = raw_input('Enter Keyword: ')
    input = input.lower()
    for characterkeyword in input:
        numberkeyword = ord(characterkeyword) - 96
        outputkeyword.append(numberkeyword)
        first = output
        second = outputkeyword

    print("The following is for debuging only")
    print output
    print outputkeyword

    outputfinal = [y - x for x, y in zip(second, first)]
    print outputfinal

mode = raw_input("Encrypt 'e' or Decrypt 'd' ")

if mode == "e":
    encryption()
elif mode == "d":
    decryption()
else:
    print("Enter a valid option")
    mode = raw_input("Encrypt 'e' or Decrypt 'd' ")

    if mode == "e":
        encryption()
    elif mode == "d":
        decryption()

Answer 1

Suppose you've got a list of numbers like a = [1, 2, 3] and an alphabet: alpha = "abcdef" . Then you convert this as follows:

def NumToStr(numbers, alpha):
    ret = ""
    for num in numbers:
        try:
            ret += alpha[num-1]
        except:
            # handle error
            pass
    return ret

Answer 2

Going by your question , you want to convert number back to text.

You can have two list declared for both the number and alphabet, such as:

num=[1,2,3....26]

alpa=['a','b','c'....'z']

and after that find the index/position from the num list and find the alphabet for that index in alpa list.

Answer 3

Although Your Question is not quite clear I wrote a script which do encryption using Dictionary

plaintext = list('ABCDEFGHIJKLMNOPQRSTUVWXYZ') #Alphabet String for Input
Etext = list('1A2B3C4D5E6F7G8H90IJKLMNOP') """Here is string combination of numbers and alphabets you can replace it with any kinda format and your dictionary will be build with respect to the alphabet sting"""              

def messageEnc(text,plain, encryp):
  dictionary = dict(zip(plain, encryp))
  newmessage = ''
  for char in text:
    try:
        newmessage = newmessage + dictionary[char.upper()]
    except:
        newmessage += ''
 print(text,'has been encryptd to:',newmessage)

def messageDec(text,encryp, plain):
 dictionary = dict(zip(encryp,plain))
 newmessage = ''
 for char in text:
    try:

        newmessage = newmessage + dictionary[char.upper()]

    except:
        newmessage += ''
 print(text,'has been Decrypted to:',newmessage)


while True:
 print("""
   Simple Dictionary Encryption :
   Press 1 to Encrypt
   Press 2 to Decrypt
   """)
  try:
     choose = int(input())
  except:
     print("Press Either 1 or 2")
     continue

  if choose == 1:

    text = str(input("enter something: "))
    messageEnc(text,plaintext,Etext)
    continue
  else:
    text = str(input("enter something: "))
    messageDec(text,Etext,plaintext)

Answer 4

A couple of things. The first is to convert the coded values back to characters you can use the chr(i) command. Just remember to ad the 96 back on.

for code in outputfinal:
        print chr(code + 96),

I tried 'aaa' as my plaintext and 'bbb' as my keyword and this printed 'ccc' which is what I think you are trying to do.

Another thing. The zip command iterates over two lists but (in my playing) only until one of the lists runs out of members. If your plaintext is 10 characters and your keyword is only 5 then only the first 5 characters of your plaintext get encrypted. You will need to expand or inflate your key to the length of your plaintext message. I played with something like this:

plaintext = ['h','e','l','l','o',' ','w','o','r','l','d']
keyword = ['f','r','e','d']

index = len(keyword) # point to the end of the key word
keyLength = len(keyword)
while index < len(plaintext): # while there are still letters in the plain text
    keyword.append(keyword[index - keyLength]) # expand the key
    index += 1

print keyword

for a,b in zip(plaintext, keyword):
    print a, b

I hope this helps. Please let me know if I have misunderstood.