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Now works on py3 also

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This commit is contained in:
Sammy Pfeiffer 2015-03-15 02:44:48 +01:00
parent 33b5708da3
commit 9df14fa6a6
2 changed files with 17 additions and 6 deletions
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2
encrypt_decrypt_ige_test.py
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@ -16,7 +16,7 @@ from ige import ige
# message must be a multiple of 16 in size
msg_to_encrypt = "This is a secret message"
padding_needed = 16 - len(msg_to_encrypt) % 16
msg_to_encrypt_padded = msg_to_encrypt + b'0' * padding_needed
msg_to_encrypt_padded = msg_to_encrypt + str(0) * padding_needed
print("Encrypting: '" + str(msg_to_encrypt) + "'")
print("With padding: '" + str(msg_to_encrypt_padded) + "'")
# 32 bytes long key

21
ige.py
View File

@ -42,14 +42,21 @@ def hex_string_to_long(val):
Convert it to int, which is actually long"""
return int(val, 16)
def xor_strings(a, b): # xor two strings of different lengths
if version_info <= (3, 4, 0):
def xor_stuff(a, b):
"""XOR applied to every element of a with every element of b.
Depending on python version and depeding on input some arrangements need to be done."""
if version_info < (3, 4, 0):
if len(a) > len(b):
return "".join([chr(ord(x) ^ ord(y)) for (x, y) in zip(a[:len(b)], b)])
else:
return "".join([chr(ord(x) ^ ord(y)) for (x, y) in zip(a, b[:len(a)])])
else:
return bytes(x ^ y for x, y in zip(a, b))
if type(a) == str and type(b) == bytes:# cipher.encrypt returns string
return bytes(ord(x) ^ y for x, y in zip(a, b))
elif type(a) == bytes and type(b) == str:
return bytes(x ^ ord(y) for x, y in zip(a, b))
else:
return bytes(x ^ y for x, y in zip(a, b))
def ige(message, key, iv, operation="decrypt"):
"""Given a key, given an iv, and message
@ -88,11 +95,15 @@ def ige(message, key, iv, operation="decrypt"):
for i in range(0, len(message), blocksize):
indata = message[i:i+blocksize]
if operation == "decrypt":
outdata = xor_strings(cipher.decrypt(xor_strings(indata, ivp2)), ivp)
xored = xor_stuff(indata, ivp2)
decrypt_xored = cipher.decrypt(xored)
outdata = xor_stuff(decrypt_xored, ivp)
ivp = indata
ivp2 = outdata
elif operation == "encrypt":
outdata = xor_strings(cipher.encrypt(xor_strings(indata, ivp)), ivp2)
xored = xor_stuff(indata, ivp)
encrypt_xored = cipher.encrypt(xored)
outdata = xor_stuff(encrypt_xored, ivp2)
ivp = outdata
ivp2 = indata
else: