Problem of the Day -- Et tu, Brute?

pegleg - 10 years, 8 months ago

TODAYSPROBLEMOFTHEDAYISTOCREATEACAESARCIPHERENCRYPTERANDDECRYPTER

pegleg - 10 years, 8 months ago

You should really let me delete my comments :-X Don't mean to ruin it

Max Burstein - 10 years, 8 months ago

No worries at all. Once someone posts a comment the comments become hidden by default so as not to ruin it for anyone else. Nice job on solving it and creating a decoder!

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Pegleg - 10 years, 8 months ago

Python 3.4

def decode(msg, number):
    temp = []
    for i in msg:
        finalnum = ord(i) + number
        if finalnum > ord('Z'):
            finalnum -=26
        elif finalnum < ord('A'):
            finalnum +=26
        temp.append(chr(finalnum))
    return ''.join(temp)
message = input('Type message to encrypt/Decrypt')
while True:
    number = input('Type number to shift by, n to close')
    if(number.lower() != 'n'):
        print(decode(message,int(number)))
    else:
        print('Laterz')
        break;

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Kevin Benton - 10 years, 8 months ago

import string
cipher = 'WRGDBVSUREOHPRIWKHGDBLVWRFUHDWHDFDHVDUFLSKHUHQFUBSWHUDQGGHFUBSWHU'

for shift in range(0,25):
   attempt = cipher
   for idx, letter in enumerate(string.uppercase):
       pointer = (idx+shift) % (len(string.uppercase))
       attempt = attempt.replace(letter, string.uppercase[pointer].lower())
   print attempt

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Daniel - 10 years, 8 months ago

My C# solution

Outputs all permutations for this Caesar cipher.

Today's answer is: TODAYSPROBLEMOFTHEDAYISTOCREATEACAESARCIPHERENCRYPTERANDDECRYPTER

   static void Main(string[] args)
    {
        string strString = "WRGDBVSUREOHPRIWKHGDBLVWRFUHDWHDFDHVDUFLSKHUHQFUBSWHUDQGGHFUBSWHU";
        string[] aryLetters = new string[26] { "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" };
        int i = 0;
        int offset;
        string strOutput;
        while (i <= 25)
        {
            strOutput = "";
            foreach (char c in strString)
            {
                offset = i + Array.IndexOf(aryLetters, c.ToString());
                offset = (offset <= 25 ? offset : (offset % 25) - 1);
                strOutput += aryLetters[offset];
            }
            Console.WriteLine(strOutput);
            Console.WriteLine();
            i++;
        }
        Console.ReadKey();
    }

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Anonymous - 10 years, 8 months ago

Another one in J.

alphabet=: 26 {. (a. i. 'A') }. a.

encrypt=: (alphabet i. ]) {"1 alphabet |."0 1~ [
decrypt=: alphabet {~ ] i."1~ alphabet |."0 1~ [

NB. Encrypt and decrypt:
3 encrypt 'TODAYSPROBLEMOFTHEDAYISTOCREATEACAESARCIPHERENCRYPTERANDDECRYPTER'
3 decrypt 'WRGDBVSUREOHPRIWKHGDBLVWRFUHDWHDFDHVDUFLSKHUHQFUBSWHUDQGGHFUBSWHU'

NB. Generate all 26 possibilities:
(i. 26) decrypt 'WRGDBVSUREOHPRIWKHGDBLVWRFUHDWHDFDHVDUFLSKHUHQFUBSWHUDQGGHFUBSWHU'

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Anonymous - 10 years, 8 months ago

python 2.7 ``` string = 'WRGDBVSUREOHPRIWKHGDBLVWRFUHDWHDFDHVDUFLSKHUHQFUBSWHUDQGGHFUBSWHU'

top = ord('Z') full_shift = top - ord('A') + 1

for i in xrange(1, full_shift): new_string = '' for l in string: dec = ord(l) + i if dec > top: dec -= full_shift new_string += chr(dec) print "index {}: {}".format(i, new_string) ```

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Anonymous - 10 years, 8 months ago

whoops! Fixed the formatting... python 2.7

string = 'WRGDBVSUREOHPRIWKHGDBLVWRFUHDWHDFDHVDUFLSKHUHQFUBSWHUDQGGHFUBSWHU'

top = ord('Z')
full_shift = top - ord('A') + 1

for i in xrange(1, full_shift):
  new_string = ''
  for l in string:
    dec = ord(l) + i
    if dec > top:
      dec -= full_shift
    new_string += chr(dec)
  print "index {}: {}".format(i, new_string)

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Jt - 10 years, 8 months ago

My first attempt at Python. Not as pretty as the already submitted answers. I tried to add a little bit, by checking to see if the answer contained words in the dictionary. Unfortunately, I ran out of time and had to cheat a bit. Given more time I should check all permutations of the encrypted string to make sure that words can be made all the way across. This will only work if the decrypted string starts with a 4 letter word or greater.

import enchant
import random

def DecryptString(encyptedStr):
  possibleSolutions = []

  offset = 0
  while offset <= 25:
    decryptedStr = ""
    for char in encyptedStr:
      charIndex = charList.index(char)
      charIndex = charIndex - offset
      if charIndex < 0:
        charIndex = charIndex + 26
      decryptedStr = decryptedStr + charList[charIndex]

    if ContainsAWord(decryptedStr):
      possibleSolutions.append(decryptedStr)
    offset = offset + 1
  return possibleSolutions

def EncryptString(str, offset):
  encryptedStr = ""
  for char in str:
    charIndex = charList.index(char)
    charIndex = charIndex + offset
    if charIndex > 25:
      charIndex = charIndex - 26

    encryptedStr = encryptedStr + charList[charIndex]   

  return encryptedStr

def ContainsAWord(str):
  dict = enchant.Dict("en_US")
  index = 4
  while index <= len(str):
    if dict.check(str[:index]):
      return True
    index = index + 1
  return False

charList = ["A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"]
encryptedString = "WRGDBVSUREOHPRIWKHGDBLVWRFUHDWHDFDHVDUFLSKHUHQFUBSWHUDQGGHFUBSWHU"

print("Possible Decrypted Strings")
for decryptedString in DecryptString(encryptedString):
  print(decryptedString)

print()
print("Randomly Encrypted String")
randomlyEncryptedString = EncryptString(decryptedString, random.randint(1,26))
print(randomlyEncryptedString)

print()
print("Possible Decrypted Strings")
for decryptedString in DecryptString(randomlyEncryptedString):
  print(decryptedString)

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Jt - 10 years, 8 months ago

I shouldn't say it only works with 4. You can lower the litmus (index) to 1, you'll just get some false positives. Apparently, "Z" is a word... The more you know.

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Hueho - 10 years, 8 months ago

MESSAGE = "WRGDBVSUREOHPRIWKHGDBLVWRFUHDWHDFDHVDUFLSKHUHQFUBSWHUDQGGHFUBSWHU"

def rot_num(num, n, range)
  wrap = num % range.begin
  range.begin + (n + wrap) % range.size
end

ALPHA = ('A'.ord)..('Z'.ord)

# In-place
def rot!(n, char_array)
  char_array.map! do |ch|
    rot_num(ch.ord, n, ALPHA).chr
  end
end

def cipher(shifts, message)
  rot!(shifts, message.chars).join
end

def decipher(shifts, message)
  cipher(shifts, message)
end

def brute_force
  char_array = MESSAGE.chars
  ALPHA.size.times do
    puts rot!(1, char_array).join
  end
end

brute_force

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Problem of the Day
A new programming or logic puzzle every Mon-Fri

Et tu, Brute?

Comments:

Problem of the Day A new programming or logic puzzle every Mon-Fri

Et tu, Brute?

Comments:

Problem of the Day
A new programming or logic puzzle every Mon-Fri