How do I translate user input into variable equivalents?

Question

I'm making an encoding and decoding program, right now I'm making the decoding program. I have substituted the entire English alphabet for a different letter (e.g. a = e, b = f, c = g) and I've written code that asks for the user to input the encrypted message using:

encrypted_message = input("Insert the encrypted message")

and I want to make it so the user can type "abc" and python would translate "abc" into "efg" and type it back.

Answer 1

Use a dictionary and then map the user's input to the dictionary's get method to retrieve each value:

>>> d = {'a':'e', 'b':'f', 'c':'g'}
>>> print(*map(d.get, 'cab'), sep='')
gef

Answer 2

Use translate() method:

For Python 2.x:

from string import maketrans

encrypted = "abc"                                 # chars to be translated
decrypted = "efg"                                 # their replacements

trantab   = maketrans(originals, encrypted)       # make translation table from them

print encrypted_message.translate( trantab )      # Apply method translate() to user input

For Python 3.x:

encrypted = "abc"                                 # chars to be translated
decrypted = "efg"                                 # their replacements

trantab   = str.maketrans(encrypted, decrypted)   # make translation table from them

print( encrypted_message.translate( trantab ) )   # Apply method translate() to user input