The longer the key, the higher the effective security. If there is ever a break in AES that reduces the effective number of operations required to crack it, a bigger key gives you a better chance of staying secure. Besides, with commodity hardware available today, the performance difference between 256-bit AES and 128-bit AES is fairly small.

256-bit AES encryption (Advance Encryption Standard) is an International standard which ensures data is encrypted/decrypted following this approved standard. It ensures high security and is adopted by the U.S. government and other intelligence organizations across the world. I saw some SWIFT code that generates IV for AES 256 from selecting 16 characters from a-zA-Z0-9 space. Is this secure? Sufficiently secure? What is the best practice to generate IV for AES 256? Will picking random 16 bytes from 0x00-0xff be good? We want to store key and IV in Database and retrieve it for encryption/decryption. It seems there are legal issues associated with AES-256 (it is disabled in Java, and Oracle tells me in their UnlimitedJCE Policy that I am "advised to consult" my "export/import control counsel or attorney to determine the exact requirements" before turning it back on and the page on Wikipedia does not look very friendly either). AES uses the same secret key is used for the both encryption and decryption. Unlike AES 128 bit encryption and decryption, if we need a stronger AES 256 bit key, we need to have Java cryptography extension (JCE) unlimited strength jurisdiction policy files.

Aug 21, 2018 · AES allows you to choose a 128-bit, 192-bit or 256-bit key, making it exponentially stronger than the 56-bit key of DES. In terms of structure, DES uses the Feistel network which divides the block into two halves before going through the encryption steps.

AES Encryption | Everything you need to know about AES

In normal use, AES keys are generated by a "truly" random source and never by a simple pseudorandom generator (like C++ rand()); AES256 is "more secure" than AES128 because it has 256-bit key - that means 2^256 possible keys to bruteforce, as opposed to 2^128 (AES128). The numbers of possible keys are shown in your table as "combinations".

How secure is encryption in Access 2007? - Stack Overflow