SIV (Synthetic Initialization Vector) is a two-pass AEAD block cipher mode of operation described in RFC 5297. It can be used either for key-wrap (nonce-less deterministic authenticated encryption) or, with a nonce, for conventional authenticated encryption with maximal tolerance of nonce reuse.
I recently came across a library that promises to do deterministic encryption with the following scheme: AES with 256 bit key in CBC mode with PKCS7 padding and Synthetic Initialization vector ...
Lets say , if we encrypt a plain text message $msg$ with key $key$ in below two ways. Which is the below would give better deterministic encryption and why ? AES-ECB($key$ , $msg$) SIV($key$, NIL , ...