Investigate SHA256 Hashing on iOS (Swift)

[nelsonic]

It appears to be possible to create a SHA256 Hash in Swift: https://stackoverflow.com/questions/25388747/sha256-in-swift

Todo

• [x] Convert Task/Timer to JSON - https://developer.apple.com/swift/blog/?id=37
• [x] Convert JSON to String
• [x] SHA256 Hash the String
• [ ] write a test to check for the output for the SHA256 Hash functions 👍
• [ ] Use the Hash as the ID in SQL-Lite DB locally on device
• [ ] Put hash into JSON Object as id field
• [ ] Send Strigified JSON to API (including id:hash)

Background Reading

• [x] Merkle Tree: https://en.wikipedia.org/wiki/Merkle_tree

Note: the reason for using a SHA256 instead of another hashing algorithm is: https://github.com/dwyl/learn-cryptography/issues/2

[nelsonic]

@sohilpandya please remember to add a Time Estimate to issues before diving in. 😉

[sohilpandya]

Thanks for that @nelsonic.

I've estimated 1.5 days for this, already spent ~3 hours on the first couple if items alongside the background reading. :)

update

• I am trying to implement this whole method on just the starting of a timer.
• Once the flow has been implemented for this, I can replicate it for when a timer ends.

[sohilpandya]

@nelsonic wanted a clarification on the following point:

Use the Hash as the ID in SQL-Lite DB locally on device

At this moment we are storing the following information in core data:

I will be adding an additional field in the core data called id which will contain the hash.

• Every time a timer is started we create this item in the core data. It will contain the hash.

Now when the user stops a timer, we are updating this item in the core data, would we update the hash too? as at the moment, the user starts a timer the hash contains the following infomation

{
  "project_name": "iOS",
  "start_date": "Stringified Date",
  "isTaskRunning": "true"
}

But when the timer is stopped it should have an additional field of "end_date":"Stringified Date"

This will mean that the hash will be different when the timer is started and when the timer is stopped.

[nelsonic]

@sohilpandya apologies if this is unclear. no, we are not updating the hash we are going to save a new revision. I am working on NHS today, but as soon as I have some time spare I will document exactly how this needs to work on both iOS and PWA so it's much clearerer. 👍

Meanwhile could you please write-up a "complete beginners" intro to automated UI testing in: https://github.com/dwyl/learn-apple-watch-development/ thanks! 🎉

[sohilpandya]

Thanks for that! I'll probably like to catch up about it early Monday morning if we can, I will look into https://github.com/dwyl/learn-apple-watch-development/issues/40 for the time being. 👍

[sohilpandya]

@nelsonic can we catch up at some point today to talk about this?

[nelsonic]

@sohilpandya dang. only saw this now... I expect to do some work on this on the train on Thursday. we should setup a hangout to catchup. 👍

[sohilpandya]

Hey @nelsonic That would be awesome, I'm planning to start working full steam from tomorrow so be great if we could catch up first thing tomorrow if that is possible?

[sohilpandya]

We only have one table, some of the main bits of information it contains:

core data
project_name
task_start_date
task_end_date
is_running

Here is the current flow of all the times we are storing to the core data

• saving new project (create)
• start a new timer (create)
• stopping a new timer (update)