Cipher/decipher program

slurpz

I'm trying to make a simple program that will convert to and from a cipher that's already set.

Expand|Select|Wrap|Line Numbers

 foo = 'a = hz\nb = ye\nc = uo\nd = pd\ne = qi\nf = jy\ng = ru\nh = sw\ni = ln\nj = ae\nk = na\nl = rt\nm = wu\nn = is\no = nd\np = hw\nq = op\nr = kb\ns = vf\nt = fc\nu = xr\nv = ex\nw = mn\nx = gb\ny = bu\nz = ie\n. =  *right wing slash* \n, =  *hand wave* \n" =  *hand curve* \n! =  *double hand jerk* \n? =  *wing wave* \n... =  *squiggly hand motion* '

repl={}

reverse_repl={}

import sys

#Generate replacement tables

for str in foo.split("\n"):

    parts=str.split(" = ")

    repl[parts[0]]=parts[1]

    repl[parts[0].lower()]=parts[1]

    reverse_repl[parts[1]]=parts[0]

def encipher():

    outstr = ''

    instr = sys.stdin.readline()

    i = 0

    for i in range(len(instr)):

        c = instr[i]

        if (instr[i:i+3]=='...'):

            outstr+=repl['...']

            i+=3

        else:

            if (c in repl):

                outstr+=repl[c]

                i+=1

            else:

                outstr+=c

                i+=1

    print outstr

def decipher():

    outstr = ''

    instr = sys.stdin.readline()

    instr=instr[:-1]

    i = 0

    c = instr[i]

    while (i<len(instr)):

            if (instr[i:i+2]):

                outstr+=reverse_repl[instr[i:i+2]]

                i+=2

            else:

                outstr+=c

                i+=1

    print outstr

if (sys.argv[1]=="-e"):

    encipher()

else:

    decipher()

raw_input('press Return to end program>')

Couple of things I couldn't get working:

I couldn't separate the '...' from the '.' The '...' will give the correct equivalent from the list when enciphering, but will also follow it with 2 instances of '.'
For deciphering, it works up until it goes up against a character that's not in "foo" like 123 or a space.

Thanks for your help in advance.

bvdet

It appears that you want to replace each character with a unique 2 character string with a special exception for "...". I don't understand what *squiggly hand motion* is, but I'll assume that it is 2 characters. If a character is not in repl, double it so we be consistent.

Your code:

Expand|Select|Wrap|Line Numbers

     for i in range(len(instr)):

        c = instr[i]

        if (instr[i:i+3]=='...'):

            outstr+=repl['...']

            i+=3

        else:

            if (c in repl):

                outstr+=repl[c]

                i+=1

            else:

                outstr+=c

                i+=1

Variable i is updated each iteration. If you assign i in the body of the loop, you will lose the assignment.
Try the following instead:

Expand|Select|Wrap|Line Numbers

     while i < len(instr):

        c = instr[i]

        if instr[i:i+3] == '...':

            outstr += repl['...']

            i+=3

        elif c in repl:

            outstr += repl[c]

            i+=1

        else:

            outstr += c*2

            i+=1

To get the code to work, I replaced your code:

Expand|Select|Wrap|Line Numbers

     while (i<len(instr)):

            if (instr[i:i+2]):

                outstr+=reverse_repl[instr[i:i+2]]

                i+=2

            else:

                outstr+=c

                i+=1

with the following code:

Expand|Select|Wrap|Line Numbers

     while i<len(instr):

        if reverse_repl.has_key(instr[i:i+2]):

            outstr += reverse_repl[instr[i:i+2]]

        else:

            outstr += instr[i][0]

        i+=2

There were several places in your code where parentheses were not required. Avoid using str as a variable name, because the built-in function str() will be masked.
HTH --BV

slurpz

Thanks for the quick reply. I actually worked a bit on my code while I waited so my code looks pretty similar to yours. My code looks like this right now:

Expand|Select|Wrap|Line Numbers

 foo = 'a = hz\nb = ye\n... =  *squiggly hand motion* \nc = uo\nd = pd\ne = qi\nf = jy\ng = ru\nh = sw\nI = xegy\ni = ln\nj = ae\nk = na\nl = rt\nm = wu\nn = is\no = nd\np = hw\nq = op\nr = kb\ns = vf\nt = fc\nu = xr\nv = ex\nw = mn\nx = gb\ny = bu\nz = ie\n. =  *right wing slash* \n, =  *hand wave* \n" =  *hand curve* \n! =  *double hand jerk* \n? =  *wing wave* '

repl={}

reverse_repl={}

import sys

#Generate replacement tables

for str in foo.split("\n"):

    parts=str.split(" = ")

    repl[parts[0]]=parts[1]

    repl[parts[0].lower()]=parts[1]

    reverse_repl[parts[1]]=parts[0]

def encipher():

    outstr = ''

    instr = sys.stdin.readline()

    i = 0

    n = len(instr)

    while i < n:

        c = instr[i] 

        if instr[i:i+3] == '...': 

            outstr += repl['...'] 

            i+=3 

        elif c in repl: 

            outstr += repl[c] 

            i+=1 

        else: 

            outstr += c

            i+=1

    print outstr

def decipher():

    outstr = ''

    instr = sys.stdin.readline()

    i = 0

    n = len(instr)

    while i < n:

        if instr[i:i+2] in reverse_repl:

            outstr+=reverse_repl[instr[i:i+2]]

            i+=2

        else:

            outstr+=instr[i]

            i+=1

    print outstr

if (sys.argv[1]=="-e"):

    encipher()

else:

    decipher()

raw_input('press Return to end program>')

Enciphering works perfectly (that "..." fix was great), but now with deciphering, there are a couple values that take up more than 2 letters.

These include:
*right wing slash* = .
*hand wave* = ,
*hand curve* = "
*double hand jerk* = !
*wing wave* = ?
*squiggly hand motion* = ...
xegy = I

Is there a more efficient way than searching for each one individually? (Maybe from an array or something?)

bvdet

You should consider processing these special cases separately. Example:

Expand|Select|Wrap|Line Numbers

 dd = {'*right wing slash*': '.',

      '*hand wave*': ',',

      '*hand curve*': '"',

      '*double hand jerk*': '!',

      '*wing wave*': '?',

      '*squiggly hand motion*': '...',

      'xegy': 'I'}
 
def fix_str(s):

    for key in dd:

        s = s.replace(key, dd[key])

    return s

Expand|Select|Wrap|Line Numbers

 
>>> print fix_str("*right wing slash**hand wave**hand curve*")

.,"

>>>

MojaveKid

2 digit encryption...the closest thing to this will be the BIFID cipher

try reading this: http://en.wikipedia.org/wiki/Bifid_cipher

it should give you a good idea on the algorithm

Cipher/decipher program

re: Cipher/decipher program

re: Cipher/decipher program

re: Cipher/decipher program

re: Cipher/decipher program

Similar Python bytes

/bytes/development

/bytes/it

/bytes/about