# Is encrypting multiple message with same key and iv secure for this case? [duplicate]

AES256, CBC

IV is sha512 of key.

How much information would be leaked from the use of the same IV & key in this way, assuming the adversary has complete access to the system, design, iv, and all information, the AES Object itself, etc etc, except the key?

$$E_k( \text{IV} \oplus \text{Random Padding} )$$
which is equidistributed among all $2^{128}$ possible values (assuming Random Padding is equidistributed among all $2^{128}$ possible values independent of the IV).