Update the crypto algos during account creation

[tarakby]

1. Looking at the account creation transaction, the algorithm checks and the error messages need to be updated to avoid confusion: although Cadence supports many signature and hash algorithms, not all of them can be used to create a Flow account. The transaction check should be updated to include only the supported algorithms by a Flow account :

• signature: ECDSA_P256 and ECDSA_secp256k1
• hash: SHA2_256 and SHA3_256
  In the current code, any other combination would pass the sanity check but the account creation would fail later.

2. Since the transaction creates a new account with a single key, the key must be a full-weight one (otherwise the new account is locked). Therefore it may be not useful to accept the key weight as an input. The transaction could hardcode the weight to 1000.

[tarakby]

@joshuahannan I'm happy to make any eventual changes, but I wanted to discuss the issue above first.

[joshuahannan]

Thanks for flagging. I didn't realize that. I'm fine if you want to update the error messages. You'll also need to update:

• https://github.com/onflow/flow-core-contracts/blob/master/transactions/accounts/add_key.cdc
• https://github.com/onflow/flow-core-contracts/blob/master/transactions/stakingCollection/create_machine_account.cdc
• https://github.com/onflow/flow-core-contracts/blob/master/transactions/stakingCollection/register_node.cdc

[tarakby]

How about the point (2) in the issue description, I think that would add a breaking change to the transaction. Should I avoid it?

[joshuahannan]

Oh yeah, sorry for missing that. I think we could remove the weight argument. We're already introducing breaking changes. Might as well make sure everything else is as we want it