Python script decrypting openssl encrypted files

aes_decrypt.py

from Crypto.Cipher import AES
import hashlib

def get_key_and_iv(password, salt, klen=32, ilen=16, msgdgst='md5'):
    mdf = getattr(__import__('hashlib', fromlist=[msgdgst]), msgdgst)
    password = password.encode('ascii','ignore')  # convert to ASCII

    try:
        maxlen = klen + ilen
        keyiv = mdf(password + salt).digest()
        tmp = [keyiv]
        while len(tmp) < maxlen:
            tmp.append( mdf(tmp[-1] + password + salt).digest() )
            keyiv += tmp[-1]  # append the last byte
            key = keyiv[:klen]
            iv = keyiv[klen:klen+ilen]
        return key, iv
    except UnicodeDecodeError:
        return None, None


if __name__ == '__main__':
    INPUT = 'toto'
    with open(INPUT, 'rb') as f:
        cipher = f.read()

    salt = cipher[8:16]
    pwd = "toto"
    key, iv = get_key_and_iv(pwd, salt, msgdgst="md5")
    ciphertext = cipher[16:]

    cipher = AES.new(key, AES.MODE_CBC, iv)
    padded_plaintext = cipher.decrypt(ciphertext)
    padding_len = padded_plaintext[-1]
    plaintext = padded_plaintext[:-padding_len]
    print(plaintext.decode('utf-8'))