Change Details

The rule against difficulty adjustments changing by more than a factor of 4 can be helpful for anti-DoS measures in contexts where we lack a full headers chain, so expose this functionality separately and in the narrow case where we only know the height, new value, and old value. The function was adjusted to account for the changes in difficulty algorithms after the 2017 BCH fork. The EDA algorithm no longer limits the difficulty change interval to 2016 blocks but still keeps the rule that the difficulty cannot change by more than a factor 4. The DAA (CW-144) and ASERTI3D algorithms no longer have hard rules for difficulty transitions, so the function always returns `true` after the november 15 2017 hard fork block height. This is a backport of [[https://github.com/bitcoin/bitcoin/pull/25717 | core#25717]] https://github.com/bitcoin/bitcoin/pull/25717/commits/84852bb6bb3579e475ce78fe729fd125ddbc715f

The rule against difficulty adjustments changing by more than a factor of 4 can be helpful for anti-DoS measures in contexts where we lack a full headers chain, so expose this functionality separately and in the narrow case where we only know the height, new value, and old value. The function was adjusted to account for the changes in difficulty algorithms after the 2017 BCH fork. The EDA algorithm no longer limits the difficulty change interval to 2016 blocks but still keeps the rule that the difficulty cannot change by more than a factor 4. The DAA (CW-144) and ASERTI3D algorithms no longer have hard rules for difficulty transitions, so the function always returns `true` after the november 15 2017 hard fork block height. This is a backport of [[https://github.com/bitcoin/bitcoin/pull/25717 | core#25717]] https://github.com/bitcoin/bitcoin/pull/25717/commits/1d4cfa4272cf2c8b980cc8762c1ff2220d3e8d51

The rule against difficulty adjustments changing by more than a factor of 4 can be helpful for anti-DoS measures in contexts where we lack a full headers chain, so expose this functionality separately and in the narrow case where we only know the height, new value, and old value. The function was adjusted to account for the changes in difficulty algorithms after the 2017 BCH fork. The EDA algorithm no longer limits the difficulty change interval to 2016 blocks but still keeps the rule that the difficulty cannot change by more than a factor 4. The DAA (CW-144) and ASERTI3D algorithms no longer have hard rules for difficulty transitions, so the function always returns `true` after the november 15 2017 hard fork block height. This is a backport of [[https://github.com/bitcoin/bitcoin/pull/25717 | core#25717]] https://github.com/bitcoin/bitcoin/pull/25717/commits/84852bb6bb3579e475ce78fe729fd125ddbc715f1d4cfa4272cf2c8b980cc8762c1ff2220d3e8d51