Suppose I want to spend from 3 unspent outputs. I must reference the txid of these unspent outputs. Suppose they are:
eb36eca9a06fbe68278ad3e7d16d10ed02e22ad891ed59ef2b84ed4a49e8a6d2 e912d1d29c2daa30cee47a89329426d254aa1ca59927b2d2ae0a2c561a30c4ad aec43a6a925e55a4f5aa3fdfa2df308912ae06636a7c92b2e19ba55e7d7fc689
Instead of pointing to the entire txids, couldn't I point to just like the first 7 digits of each, so it'd be
Of course, it's easy to generate a txid that matches just the 7 first digits of each of the used txids. But what if we also included the information that, once you find these 3 txids in the database that start with
aec43a6, the hash of these 3 entire txids must be equal
hash(eb36eca9a06fbe68278ad3e7d16d10ed02e22ad891ed59ef2b84ed4a49e8a6d2 + e912d1d29c2daa30cee47a89329426d254aa1ca59927b2d2ae0a2c561a30c4ad + aec43a6a925e55a4f5aa3fdfa2df308912ae06636a7c92b2e19ba55e7d7fc689) (where + here is concatenation).
So instead of including all 3 txids, we just include the first n digits of each and the hash of these 3 txids concatenated.
Wouldn't it free a lot of space? It's just one hash +
n the number of first digits, and
k the number of inputs.
Also, wouldn't Schnorr signatures make it possible to sign all these outputs with just 1 signature? Wouldn't it make all transactions have almost the same size? Today, each new output adds to the transaction size at least: it txid and signature, which are the biggest parts.