I've managed to get AES/Rijndael [256bit key / 128bit block size] symmetric encryption working: encrypt with pycrypto and decrypting with Botan in C++.
However, when I try to base64 encode the encryption result in python, the resulting string is shorter than the same string generated by Botan using a Base64_Encoder. Example:
Botan Base64:
zjjxmJf5KPs183I/EvC+JuNbOdmbm4bWyhLsdZI8fuVUnKQAeSj0ivmKIYu7HBjM7gLgLV+xtSKcsCeQD7Gy4w==
Py-3k Base64:
zjjxmJf5KPs183I/EvC+JuNbOdmbm4bWyhLsdZI8fuVUnKQAeSj0ivmKIYu7HBjM
You can see that the strings are exactly the same up until the 64 character mark. If I try to decrypt the Python base64 string in Botan it complains about "not enough input".
How do I get the Python base64 string to be acceptable by Botan?
-- EDIT --
When decoding the Botan base64 encoded string in Python:
Botan Decoded:[b'\xce8\xf1\x98\x97\xf9(\xfb5\xf3r?\x12\xf0\xbe&\xe3[9\xd9\x9b\x9b\x86\xd6\xca\x12\xecu\x92<~\xe5T\x9c\xa4\x00y(\xf4\x8a\xf9\x8a!\x8b\xbb\x1c\x18\xcc\xee\x02\xe0-_\xb1\xb5"\x9c\xb0\'\x90\x0f\xb1\xb2\xe3']
Botan Encoded:[b'zjjxmJf5KPs183I/EvC+JuNbOdmbm4bWyhLsdZI8fuVUnKQAeSj0ivmKIYu7HBjM7gLgLV+xtSKcsCeQD7Gy4w==']
Thus, the Python pycrypto result:
Encryption result: b'\xce8\xf1\x98\x97\xf9(\xfb5\xf3r?\x12\xf0\xbe&\xe3[9\xd9\x9b\x9b\x86\xd6\xca\x12\xecu\x92<~\xe5T\x9c\xa4\x00y(\xf4\x8a\xf9\x8a!\x8b\xbb\x1c\x18\xcc'
Base64 encoded: b'zjjxmJf5KPs183I/EvC+JuNbOdmbm4bWyhLsdZI8fuVUnKQAeSj0ivmKIYu7HBjM
Python seems to be "omitting" something. But what?
-- EDIT 2 --
When I try to base64decode & decrypt the pycrypto result, Botan throws this:
Botan exception caught: Buffered_Operation::final - not enough input
So pycrypto is not producing "enough" output such that it can be decrypted by Botan.
-- EDIT 3 ---
Code examples:
Python: changed sensitive info.
import sys
import base64
import binascii
from Crypto.Cipher import AES
plaintext = "097807897-340284-083-08-8034-0843324890098324948"
hex_key = b'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'
key = binascii.unhexlify( hex_key )
hex_iv = b'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'
iv = binascii.unhexlify( hex_iv )
aes_enc_bytes = AES.new(key, AES.MODE_CBC, iv).encrypt( plaintext )
aes_enc = base64.encodebytes(aes_enc_bytes )
print( "Encrypted:[{}]".format( aes_enc ) )
aes_dec = AES.new(key, AES.MODE_CBC, iv).decrypt( binascii.a2b_base64( aes_enc ) )
print( "Decrypted:[{}]".format( aes_dec ) )
C++ (Qt + Botan)
void botanDecryptor::decrypt()
{
Botan::SymmetricKey key( private_key );
Botan::InitializationVector iv( iv_value );
try
{
// Now decrypt...
Botan::Pipe dec_pipe(new Base64_Decoder, get_cipher("AES-256/CBC", key, iv, Botan::DECRYPTION));
dec_pipe.process_msg( ciphertext );
string decrypted = dec_pipe.read_all_as_string();
cout << "Decrypted:[" << decrypted << "]" << endl;
}
catch(Botan::Exception& e)
{
cout << "Botan exception caught: " << e.what() << endl;
return;
}
-- EDIT 4 --
I decided to try and decrypt the Botan encrypted, base64 encoded string in python and it worked, but it added a bunch of what looks like padding:
Decrypted:[b'097807897-340284-083-08-8034-0843324890098324948\x10\x10\x10\x10\x10\x10\x10\x10\x10\x10\x10\x10\x10\x10\x10\x10']
I then proceeded to add that padding to my pycrypto result before base64 encoding to produce the following, which Botan refuses to decrypt ;(
zjjxmJf5KPs183I/EvC+JuNbOdmbm4bWyhLsdZI8fuVUnKQAeSj0ivmKIYu7HBjMEBAQEBAQEBAQ\nEBAQEBAQEA==
-- ANSWER --
(system wouldn't allow me to self answer for another 5 hours!)
I've finally schlepped through all the documentation and found the answer! One needs to specify what padding method is to be used for the mode. I specified NoPadding e.g.
Pipe dec_pipe(new Base64_Decoder, get_cipher("AES-256/CBC/NoPadding", key, iv, Botan::DECRYPTION));
and viola! The output matches the pycrypto exactly. For reference: [http://botan.randombit.net/filters.html][1]
[1]: Botan Docs: Cipher Filters
