SHA256 online Hash Generator

I've been trying to find the preimage for the following hash:56944c5d3f98413ef45cf54545538103cc9f298e0575820ad3591376e2e0f65d

This is the hash that is output after the initialisation of the CHashWriter function in Bitcoin. Xcode is telling that the data portion on initialisation is 16 unsigned ints of value 0, ie. 512 0 bits. Checking elsewhere, if we were to consider that as a pre-image, the output is not the same: the resulting hash is f5a5fd42d16a20302798ef6ed309979b43003d2320d9f0e8ea9831a92759fb4bCould anyone explain where the initial hash comes from?

I've done some looking around but i've only been able to find examples that use Objective-C to create SHA256 hashes. Is there a way to do this with only Swift4?

We've built a javascript module which can be embedded in third-party webpages. When this client module is initialized, it executes a transaction within our web application via a cross-site request.

The transaction consists of an external uuid, an email, and some additional meta properties. This message is signed with an HMAC sha256 digest, using our partner's private API key.

Ruby example:

data = {  uuid: "ABCAFAFDS",  email: "email@gmail.com",  meta: {}}private_key = "Qd9fe0y2ezqfae4Qj6At"signature = OpenSSL::HMAC.hexdigest(  OpenSSL::Digest.new("sha256"),  private_key,  data.to_json)

Within the third-party webpage, the javascript client is then initialized with the signature and the data:

new Client(signature, data).execute();

Initially, our plan was to allow the client to create a partial / incomplete transaction within our system and then require a subsequent back-end request via our REST API to confirm / finalize the transaction. Assuming that we can secure the front-end, however, it would be preferential to remove the back-end confirmation requirement.

Can we reasonably secure the client code using signed messages in this fashion? If the data and the signed message is available in the client, how difficult would it be for a bad actor to brute force the API private key length, given the length above?

I've tried to deploy an OVF export on VMWare Workstation.I received the following message:

SHA1 digest of file "appliance.ovf" does not match manifest.

Upon investigating the issue, I've discovered that SHA1 has been dropped and VMWare only accepts manifests that have a SHA256 hash.

My questions are if I delete the appliance.mf file, will it still import maintaining the structure of the .ovf export? Or will it generate a new hash based on SHA256?? Or how can I generate a new SHA256 hash for the .ovf file?

I have big database with user and passwords in sha256 hash. Now I write new version and I want to use sha256+salt. Is there a way to convert same passwords with sha256 to sha256+salt and have no trouble with login?