From 56e909458bb73ae430d5e7816f82e4579c600ec1 Mon Sep 17 00:00:00 2001 From: Anthony Towns Date: Sat, 13 Dec 2025 12:00:27 +1000 Subject: [PATCH] bip-325: document signet minimum difficulty This was implicit in the genesis block's nbits value, but better to be clearer. --- bip-0325.mediawiki | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/bip-0325.mediawiki b/bip-0325.mediawiki index be4ad021..e0bdc30e 100644 --- a/bip-0325.mediawiki +++ b/bip-0325.mediawiki @@ -75,6 +75,15 @@ A block is considered fully validated only if the to_sign transaction is a valid There is one other acceptable special case: if a block's challenge is e.g. `OP_TRUE` (`0x51`), where an empty solution would result in success, the block is also considered valid if the signet commitment is absent. +=== Minimum Difficulty === + +The minimum difficulty for blocks in signet is approximately +0.0011265, corresponding to a maximum target of +00000377ae000000000000000000000000000000000000000000000000000000 +which is represented by an nBits value of 0x1e0377ae. + +This value is chosen so that multiplying the maximum target by maximum retarget timespan (8 weeks measured in seconds) does not overflow a uint256, making it easier to do difficulty adjustment calculations. + == Genesis Block and Message Start == The genesis block is the same for all signet networks, whereas the message start is defined as the first four bytes of the sha256d of the challenge script as a single data push (see below).