AES Encryption in Python is different form iOS
Question: I am trying to encrypt a string in IOS and then send it to a TCP server.
Python version of code and iOS versions are shown below. Please see outputs of
the both versions. They look quite similar but the lengths are different and I
do not know the reason. Can anybody check it , what could be the reason?

Please note that PADDING in Python script should be discarded , as I gave a
text length of 16 already.

PYTHON Code:

    
    
         #!/usr/bin/env python
    
         from Crypto.Cipher import AES
         import base64
         import os
    
         # the block size for the cipher object; must be 16, 24, or 32 for AES
         BLOCK_SIZE = 16
    
         PADDING = '{'
    
         # one-liner to sufficiently pad the text to be encrypted
         pad = lambda s: s + (BLOCK_SIZE - len(s) % BLOCK_SIZE) * PADDING
    
         # one-liners to encrypt/encode and decrypt/decode a string
         # encrypt with AES, encode with base64
         EncodeAES = lambda c, s: base64.b64encode(c.encrypt(pad(s)))
         DecodeAES = lambda c, e: c.decrypt(base64.b64decode(e)).rstrip(PADDING)
    
    
         secret = "1234567890123456" 
    
         # create a cipher object using the random secret
         cipher = AES.new(secret)
    
         encoded = EncodeAES(cipher, 'password12345678')
         print 'Encrypted string:', encoded
    
         decoded = DecodeAES(cipher, encoded)
         print 'Decrypted string:', decoded
    

OUTPUT:

Encrypted string: 57AayWF4jKYx7KzGkwudIBZUsn1ULOC0C4c5YF3xeI8=

Decrypted string: password12345678

    
    
    NSString *forKey=@"1234567890123456";
    NSString *mystr =@"password12345678";
    const char *utfString = [mystr UTF8String];
    NSData *aData=[NSData dataWithBytes: utfString length: strlen(utfString)];
    aData=[mystr dataUsingEncoding:NSUTF8StringEncoding];
    NSData *data;//=[aData AES128EncryptWithKey:forKey];
    data=[aData AES128EncryptWithKey:forKey];
    
    NSString *base64 = [data base64EncodedString];
    
    aData=[data AES128DecryptWithKey:forKey];
    mystr=[[NSString alloc] initWithData:aData encoding:NSUTF8StringEncoding];
    
    NSLog(@"AES data : %@  \n %@",mystr,base64 );
    

OUTPUT:

AES data : password12345678  
57AayWF4jKYx7KzGkwudIKNlwA+HErrmiy1Z0szzZds=


Answer: OK , here it is. Thanks sarnold for the clue :)

    
    
    from Crypto.Cipher import AES
    import base64
    import os
    
        # the block size for the cipher object; must be 16, 24, or 32 for AES
        BLOCK_SIZE = 16
        mode = AES.MODE_CBC
        secret = "1234567890123456" #os.urandom(BLOCK_SIZE)
    
        # create a cipher object using the random secret
        cipher = AES.new(secret,mode)
    
        # encode a string
        #tx=cipher.encrypt('1234567890123456')
        #print base64.b64encode(tx)
    
        myData='aaaaaaaaaaaaaaaa'
        #encoded = EncodeAES(cipher, myData)
        encoded = cipher.encrypt(myData)
        print 'Encrypted string:', base64.b64encode(encoded)
        mode = AES.MODE_ECB
        cipher=AES.new(secret,mode)
        decoded = cipher.decrypt(encoded)
        print 'Decrypted string:', decoded
    

**Python OUTPUT:**

Encrypted string: C9pEG6g8ge76xt2q9XLbpw==

Decrypted string: aaaaaaaaaaaaaaaa

> *Changed AES CCOptions to kCCOptionECBMode in iOS. *
    
    
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionECBMode,keyPtr, CCKeySizeAES128, NULL,[self bytes], dataLength,  buffer, bufferSize,  &numBytesEncrypted);
    

And now output is:

**iOS Output:**

AES data : aaaaaaaaaaaaaaaa  
C9pEG6g8ge76xt2q9XLbpw==

