what does mac stand for in information security

ECB involves independently encrypting each block with the same key, without any data fed between blocks. The most simple block mode is ECB, which offers zero security in this regard. This is where block modes, like CBC, come into play.īlock modes aim to make ciphers secure for encrypting multiple blocks with the same key. The problem is that we rarely want to just encrypt one block, but rather a data stream of indeterminate length. Block ciphers, such as AES, aim to be secure for encrypting one block with a secret key. The diagram you posted above describes CBC. Discussing the technicalities around the security of AES and similar block ciphers is extremely involved and not something I can cover in an answer, but suffice to say that thousands of cryptographers have been looking at it for almost two decades and nobody has found anything remotely practical in terms of an attack. Without the key, AES might as well be a one-way function (and there are MAC schemes which rely upon this!).

Ignoring the internals of it for a moment, AES is considered secure in that without knowing the key, it's practically impossible to recover the plaintext or any information about the plaintext given only an encrypted block, or even in situations where you're given parts of the plaintext and you need to find the remainder. I think it's easier to split this into its component parts, and consider them as separate entities: AES and CBC.ĪES itself does not 'basically consist of XORing together chunks of the block' - it's a much more complicated affair.

What does mac stand for in information security