How do you make 2 or more keys to sign a transaction and verify the keyset?

Question

When building keysets, they have three options: keys-all, keys-2, and keys-any. I wanted to create a keyset that required 3 keys to sign the transaction, but I was confused about how to force the keyset to take all three keys in the signature section.

Answer 1

The validity of the keyset is checked through the predicate (pred). The predicate can be any function that is fed as arguments:

• the number of keys in the keyset
• the count of matching signatures

If the predicate returns true the transaction can continue. You can construct custom predicates matching this function signature:

(defun keys-3:bool(count:integer matched:integer)
  (>= matched 3))

And then create a keyset using that custom predicate:

(env-data {
  "my-keyset": {"keys": ["bob", "alice", "babena" ],
  "pred": "my-module.keys-3"}
})