Lots of people read the Bitcoin Core codebase to learn more about
crypto; better to warn about flaws explicitly so they don't blindly copy
the code for other uses and create broken systems.
redeemScripts >520bytes can't be spent due to the
MAX_SCRIPT_ELEMENT_SIZE limit; previously the addmultisigaddress and
createmultisig RPC calls would let you violate that limit unknowingly.
Also made the wallet code itself check the redeemScript prior to adding
it to the wallet, which in the (rare) instance that a user has added an
invalid oversized redeemScript to their wallet causes an error on
startup. The affected key isn't added to the wallet; other keys are
unaffected.
Removes the limits on number of pubkeys for P2SH CHECKMULTISIG outputs.
Previously with the 500 byte scriptSig limit there were odd restrictions
where even a 1-of-12 P2SH could be spent in a standard transaction(1),
yet multisig scriptPubKey's requiring more signatures quickly ran out of
scriptSig space.
From a "stuff-data-in-the-blockchain" point of view not much has changed
as with the prior commit now only allowing the dummy value to be null
the newly allowed scriptSig space can only be used for signatures. In
any case, just using more outputs is trivial and doesn't cost much.
1) See 779b519480d8c5346de6e635119c7ee772e97ec872240c45e558f582a37b4b73
Mined by BTC Guild.
This is a source of transaction mutability as the dummy value was
previously not checked and could be modified to something other than the
usual OP_0 value.
Previously CreateNewBlock() didn't take into account the fact that
IsFinalTx() without any arguments tests if the transaction is considered
final in the *current* block, when both those functions really needed to
know if the transaction would be final in the *next* block.
Additionally the UI had a similar misunderstanding.
Also adds some basic tests to check that CreateNewBlock() is in fact
mining nLockTime-using transactions correctly.
Thanks to Wladimir J. van der Laan for rebase.
Previously bitcoin-qt's -debug transaction info was showing CTxOut([error])
It is valid for a scriptPubKey to be any size, for example simply
OP_RETURN is valid and can be used to destroy a TXOUT to mining fees.
Seems it was forgotten about when IsPushOnly() and the unittests were
written. A particular oddity is that OP_RESERVED doesn't count towards
the >201 opcode limit unlike every other named opcode.
Previously when a transaction was set to lock at a specific block the
calculation was reversed, returning a negative number. This broke the UI
and caused it to display %n in place of the actual number.
In addition the previous calculation would display "Open for 0 blocks"
when the block height was such that the next block created would
finalize the transaction. Inserted the word "more" and changed the
calculation so that the last message would be "Open for 1 more block" to
better match user expectations.
Previously trying to create a multisig address that required less than
one signature would output something like the following:
"wrong number of keys(got 1, need at least 0)"
Peter Todd