Using hash_tree_root for DepositData

[hwwhww]

What was wrong?

Implement ethereum/consensus-specs#924 related changes

How can it be fixed?

1. Update deposit APIs to: def deposit(pubkey: bytes[48], withdrawal_credentials: bytes[32], amount: bytes[8], signature: bytes[96])
2. Implement hash_tree_root of DepositData in contract
3. Add tests for it

[NIC619]

Should we also incorporate the data length check as suggested in ethereum/consensus-specs#710 (comment) into this?

[djrtwo]

I think we'll need to still assert length checks on all of these bytes types or ensure that we pad them out. Length checks is probably safer for user.

I don't think we need to include "amount" explicitly anymore as it can be dynamically built and hashed into the tree hash

[hwwhww]

@djrtwo

I think we'll need to still assert length checks on all of these bytes types or ensure that we pad them out. Length checks is probably safer for user.
I don't think we need to include "amount" explicitly anymore as it can be dynamically built and hashed into the tree hash

If we remove the amount field, I think the only field we need to do length check is exactly the little-endian-encoded amount.

@daejunpark hello! And, and thought/consideration about it? :)