is it possible to retrieve AES key using AES initalization vector and encrypted data?
I have AES initalization vector and encrypted data. I have seen a online tool for decrypting AES encrypt data using AES key and AES initalization vector.
online tool: http://aes.online-domain-tools.com
When i entered any key in AES key field, it is showing AES initalization vector in initialization field.
So, I have question that if i have AES initalization vector then is it possible to retrieve AES key?
No, the AES key cannot be retrieved from the initialization if AES was applied correctly. In that case the IV and AES key should be independent of each other.
Sometimes the AES key and IV are however generated by hashing over some common value. This is not a secure method of creating an IV. In that case the IV can possibly be used as distinguisher to validate if a particular key is correct (but in general such a test can also be performed over the ciphertext. Deriving the IV from the key makes the use of an IV moot in the first place, IV's should be used to make a cipher secure when a key is reused!
Sometimes the AES key is not generated correctly, for instance by using MD5 over weak password, or by directly applying a password as a key (after padding it to the required size). In that case you may use a dictionary (and related) attacks, basically brute forcing the password to get the key. It is easier to test the correctness of the result if the IV is directly derived from the key .
Both above techniques seem to be used by the above online tool. It clearly shows you how not to apply AES.. Don't trust shit websites that are popular because they just choose an interesting name.
