encryption decryption - encryption

Question

I am trying to create a custom encryption/decryption code in python. I read few articles and found that I can store the encryption ciphers in the dictionary. I tried using it but it is not working. keys will be letters in alphabetical order(A-Z) and values will be the letters that I want to put(ciphers). There is no specifics shift pattern in the encryption cipher. There are also numbers(0-9) in the encryption-decryption. they are in sequence though.
dict = {'A' : 'O', 'B' : 'P', 'C' : 'J' ......'Z' : 'Z', ....
'0' : 9, '1' : 8, ............'8' : 1, '9' : 0}
These encrypted password will be stored in a database. I need help to create the code to encrypt and decrypt the password. If there's any other method to start with please let me know.

Answer 1

If you don't want to use the Python Cryptography Module...
Here's some code that may help:
I'm replacing your dict with the name en_dict
#unencrypted_item should be a string
def encrypt(unencrypted_item):
result = ""
for i in unencrypted_item:
result+=en_dict[i]
return result
def encrypt(encrypted_item):
result = ""
for i in encrypted_item:
for n in en_dict:
if en_dict[n] == i:
result += n
break
return result

Answer 2

Try mapping the original string with the keys in your dictionary.
mapping = {'A':'Z', 'B':'C', '1':'0', '2':'7'}
reverse_mapping = dict((j,i) for i,j in mapping.items())
string_to_encrypt = 'AB1'
encrypted_string = ''.join(map(mapping.__getitem__, string_to_encrypt))
print(encrypted_string) #ZC0
decrypted_string = ''.join(map(reverse_mapping.__getitem__, encrypted_string))
print(decrypted_string) #AB1

Answer 3

Firstly, I hope that you plan to use your encryption scheme for academic purposes only because this simple substitution cipher is very insecure. For the most basic level of security you should look at storing salted hashes of user passwords instead, or use something like bcrypt.
WRT to your specific question, use your mapping dictionary with str.translate() to translate the string in one go without the need to explicitly loop in your code, or use other functions such as map() and join().
encrypt_dict = {'A': 'O', 'B': 'P', 'C': 'J', 'Z': 'Z', '0': 9, '1': 8, '8': 1, '9': 0}
tr_encrypt = {ord(str(k)): ord(str(encrypt_dict[k])) for k in encrypt_dict}
tr_decrypt = {tr_encrypt[k]: k for k in tr_encrypt}
plaintext = 'ABCZ0189'
ciphertext = plaintext.translate(tr_encrypt)
>>> ciphertext
'OPJZ9810'
assert ciphertext.translate(tr_decrypt) == plaintext
plaintext = 'THIS IS test 128'
ciphertext = plaintext.translate(tr_encrypt)
>>> ciphertext
'THIS IS test 821'
assert ciphertext.translate(tr_decrypt) == plaintext
The first few lines set up encryption and decryption translation tables in the form required by str.translate(). Then it's simply a matter of calling translate on the string to encrypt and decrypt as required.
The second example shows that any character in the string that is not present in the translation table is left unchanged which may or may not be what you want. You can create a translation mapping that covers all expected characters, but that's potentially a lot if you are using unicode.

Answer 4

I think this is what you want. You can use string.printable[:61] where string.printable prints all the ASCII characters and [:61] takes all characters from index 0 to 61 - which are letters and numbers
import string
import random
normla_l=list(string.printable[:61])
new_l=list(string.printable[:61])
random.shuffle(new_l)
see_list={x:y for x,y in zip(normla_l,new_l)}
def change_list(char):
return see_list.get(char) if char!='' else random.choice(normla_l)
x=input("Enter string: ")
print(''.join([change_list(char.strip()) for char in x]).strip())
Sample
Enter string: This string will be encrypted
Xqv7G74HvTxbPv55psIVITzHhg4IN