python - IV must be 16 bytes long error in AES encryption -

i using pycrypto module aes encryption. , using documentation have write down below function al;ways gives error iv must 16 bytes long using 16 byte long iv.

def aes_encrypt(plaintext):     """     """     key = **my key comes here**     iv = binascii.hexlify(os.urandom(16)) # used without binascii.hexlify)      aes_mode = aes.mode_cbc      obj = aes.new(key, aes_mode, iv)      ciphertext = obj.encrypt(plaintext)     return ciphertext 

use this:

from crypto.cipher import aes  import binascii,os  def aes_encrypt(plaintext):     key = "00112233445566778899aabbccddeeff"     iv = os.urandom(16)     aes_mode = aes.mode_cbc     obj = aes.new(key, aes_mode, iv)     ciphertext = obj.encrypt(plaintext)     return ciphertext 

works below:

>>> aes_encrypt("testtesttesttest") 'r_\x18\xaa\xac\x9c\xdb\x18n\xc1\xa4\x98\xa6sm\xd3' >>>  

that's difference:

>>> iv =  binascii.hexlify(os.urandom(16)) >>> iv '9eae3db51f96e53f94dff9c699e9e849' >>> len(iv) 32 >>> iv = os.urandom(16) >>> iv '\x16fdw\x9c\xe54]\xc2\x12!\x95\xd7zf\t' >>> len(iv) 16 >>>