Quote from: hosseinimr93 on Today at 03:31:13 PM

Isn't there any maximum limit for total number of cosigners?
As you know, electrum allow increasing the number of consigners up to 15. Isn't that the maximum number of cosigners we can have or that's just a limit enforced by electrum?

If I am not wrong, the p2sh script size can't be more than 520 bytes and that should limit the total number of cosigners we can have in a multi-signature address.

Technically the OP_CHECKMULTISIG(VERIFY) operations have a consensus critical check where they limit the number to 20 public keys[1][2] but the actual maximum number of public keys used in a multi-sig script depends on the type of the script and the public key length (compressed/uncompressed).
- For a raw P2MS script where the locking script is inside the scriptpub you can have up to 20 pubkeys regardless of the type since there is no size limit in consensus rules.
- But for a P2SH script where there is a redeem script (containing pubkeys) that needs to be pushed to the stack, the size is limited by that Push OP and to 520 bytes as you said. So it is 520/65=8 -extra bytes = 7 uncompressed pubkeys and 520/33=15 compressed pubkeys.

[1] https://github.com/bitcoin/bitcoin/blob/d09c8bc730d8d412ddc9b040cbeeb49dff3104de/src/script/interpreter.cpp#L1116
[2] https://github.com/bitcoin/bitcoin/blob/d09c8bc730d8d412ddc9b040cbeeb49dff3104de/src/script/script.h#L30

Quote from: o_e_l_e_o on Today at 03:43:18 PM

In taproot, OP_CHECKMULTISIG/OP_CHECKMULTISIGVERIFY are replaced with OP_CHECKSIGADD (0xba), which allows up to 999 keys.

Isn't that a standard rule? I can't see this enforced anywhere else:
https://github.com/search?q=repo%3Abitcoin%2Fbitcoin+MAX_PUBKEYS_PER_MULTI_A+&type=code