EIP-3554: Difficulty Bomb Delay to December 1st 2021 (#2289)

* implemented EIP-3554: Difficulty Bomb Delay to December 1st 2021

Signed-off-by: Karim TAAM <karim.t2am@gmail.com>

* update CHANGELOG.md

Signed-off-by: Karim TAAM <karim.t2am@gmail.com>

CHANGELOG.md

@@ -8,6 +8,7 @@
 * Added support for the London Network Upgrade, although the block number must be set manually with `--override-genesis-config=londonBlock=<blocknumber>`. This is because the block numbers haven't been determined yet. The next release will include the number in the genesis file so it will support London with no intervention. [\#2237](https://github.com/hyperledger/besu/pull/2237)
 * Implemented [EIP-3541](https://eips.ethereum.org/EIPS/eip-3541): Reject new contracts starting with the 0xEF byte [\#2243](https://github.com/hyperledger/besu/pull/2243)
 * Implemented [EIP-3529](https://eips.ethereum.org/EIPS/eip-3529): Reduction in refunds [\#2238](https://github.com/hyperledger/besu/pull/2238)
+* Implemented [EIP-3554](https://eips.ethereum.org/EIPS/eip-3554): Difficulty Bomb Delay [\#2289](https://github.com/hyperledger/besu/pull/2289)
 
 
 ### Bug Fixes

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/MainnetDifficultyCalculators.java

@@ -39,6 +39,7 @@ public abstract class MainnetDifficultyCalculators {
   private static final long BYZANTIUM_FAKE_BLOCK_OFFSET = 2_999_999L;
   private static final long CONSTANTINOPLE_FAKE_BLOCK_OFFSET = 4_999_999L;
   private static final long MUIR_GLACIER_FAKE_BLOCK_OFFSET = 8_999_999L;
+  private static final long LONDON_FAKE_BLOCK_OFFSET = 9_699_999L;
 
   private MainnetDifficultyCalculators() {}
 
@@ -82,6 +83,11 @@ public abstract class MainnetDifficultyCalculators {
       (time, parent, protocolContext) ->
           calculateThawedDifficulty(time, parent, MUIR_GLACIER_FAKE_BLOCK_OFFSET);
 
+  // As per https://eips.ethereum.org/EIPS/eip-3554
+  static DifficultyCalculator LONDON =
+      (time, parent, protocolContext) ->
+          calculateThawedDifficulty(time, parent, LONDON_FAKE_BLOCK_OFFSET);
+
   private static BigInteger calculateThawedDifficulty(
       final long time, final BlockHeader parent, final long fakeBlockOffset) {
     final BigInteger parentDifficulty = difficulty(parent.getDifficulty());

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/MainnetProtocolSpecs.java

@@ -575,6 +575,7 @@ public abstract class MainnetProtocolSpecs {
                 MainnetEvmRegistries.london(gasCalculator, chainId.orElse(BigInteger.ZERO)))
         .transactionPriceCalculator(transactionPriceCalculator.orElseThrow())
         .eip1559(Optional.of(eip1559))
+        .difficultyCalculator(MainnetDifficultyCalculators.LONDON)
         .gasBudgetCalculator(TransactionGasBudgetCalculator.eip1559(eip1559))
         .blockHeaderValidatorBuilder(MainnetBlockHeaderValidator.createEip1559Validator(eip1559))
         .ommerHeaderValidatorBuilder(