Python Simple Substitution Cypher

encrypt1.py

#!/usr/bin/env python

in_str = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ '
out_str = 'jklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghi'

def encrypt1(the_string):
    the_result = ''
    for x in the_string:
        pos = in_str.find(x)
        the_result += out_str[pos]
    return the_result

def decrypt1(the_string):
    the_result = ''
    for x in the_string:
        pos = out_str.find(x)
        the_result += in_str[pos]
    return the_result

def encrypt2(the_string):
    the_result = ''
    for x in the_string:
        pos = in_str.find(x)
        # have to deal with what happens if x isn't in in_str
        if pos > -1:
            the_result += out_str[pos]
    return the_result

def decrypt2(the_string):
    the_result = ''
    for x in the_string:
        pos = out_str.find(x)
        # have to deal with what happens if x isn't in out_str
        if pos > -1:
            the_result += in_str[pos]
    return the_result

def encrypt3(the_string):
    the_result = ''
    for x in the_string:
        the_result += out_str[in_str.find(x)]
    return the_result

def decrypt3(the_string):
    the_result = ''
    for x in the_string:
        the_result += in_str[out_str.find(x)]
    return the_result

def encrypt_decrypt(the_string, do_encrypt = True):
    # this function encrypts and decrypts all in one place
    the_result = ''
    # only do this check once, no need to check every time
    # you go through the loop - instead use two loops
    if do_encrypt:
        for x in the_string:
            the_result += out_str[in_str.find(x)]
    else:
        for x in the_string:
            the_result += in_str[out_str.find(x)]
    return the_result

if __name__ == '__main__':
    # Enctype the string
    encrypted = encrypt3('some random string')
    # print it to the console
    print(encrypted)
    # print the decrypted string to the console
    print(decrypt3(encrypted))

    encrypted = encrypt_decrypt('some random string')
    # print it to the console
    print(encrypted)
    # print the decrypted string to the console
    print(encrypt_decrypt(encrypted, False))