* Open Issues

** Why does PartialTransaction have a "blinding"?

I believe it should only have a derived balance field.

** Poseidon Constants for Grumpkin Field

Generating the poseidon constants for the Grumpkin curve is very slow, like takes 1 minute.

I need to pre-generate these to make the curve work.


** Solvers need the value of a note in order to solve it

- do users provide a merkle proof showing the value is legit?

- merkle proofs also reveal positional information.
- if we are to reveal partial information to solvers
  we will need to blind the other leaf nodes of the tree:

  Note = VALUE || UNIT || ....

  com =      ..root..
          /          \
   h(h(V), h(U))     ...
     /     \
 h(VALUE) h(UNIT)
    |       |
  VALUE    UNIT

  Revealing the value's merkle path would reveal h(UNIT) and since UNIT is well known, h(UNIT) is also easily computable.

  Thus each component of the Note should have a blinding factor
  Note = (r1, VALUE) || (r1, UNIT) || ....

** Transferring requires recipients sk

We need to be able to create a partial transaction where we don't know the output note's nullifier.

What we need: A public note + balance commitment

balance commitment is computed as

```
value <- known by transaction builder
unit <- known by transaction builder
blinding <- PRF_r(nullifier) !!!! <-- this is where the issue is
funge <- hash_to_curve(Unit)
balance_commit <- pedersen_commit(value, blinding, funge)
```

Why is the blinding a PRF of the nullifier? Can't we simply use the randomness of the transaction to derive a blinding factor?

*** How does zcash solve this?

They provide specific randomness for this when building the transaction.


** Note Unit should be a string hashed to curve point when needed.
We want human readable units (i.e. "ETH" "NMO")

I've gone and denoted it as bytes.


* Solved
** Do we need note.randomness?

It's currently used in the note commitment. But perhaps it's not really necessary?

- it allows you to get away form content based addressing, this may be necessary for total privacy.

Yes, we need this