Introduce a 32 gas minimum base fee equivalent for including an entry in ACL

EIPS/eip-000.md

@@ -1,9 +1,9 @@
 ---
 eip: 0
 title: Global Warming
 description: Block-level warming of addresses and slots with access lists
 author: Yoav Weiss (@yoavw), Alex Forshtat (@forshtat), Dror Tirosh (@drortirosh), Shahaf Nacson (@shahafn)
 discussions-to:
 status: Draft
 type: Standards Track
 category: Core
@@ -149,6 +149,16 @@
 As all transactions in the same block pay exactly the same `baseFeePerGas`, the single cost of accessing a cold item is
 divided evenly among all transactions containing such access and the rest of the burned base fee is refunded.
 
+### Setting an absolute minimal cost of cold state access
+
+If a large number of transactions all access the same addresses or slots, the cost of each cold access may get
+way too low which may represent a potential DoS attack vector.
+
+In order to prevent that, the gas cost of including an entity in the access list cannot be lower
+than `MIN_ACCESS_LIST_ENTRY_COST`, which is set to `32 gas`.
+
+This value is equivalent to the calldata cost of including two bytes long identifier of entries in `block_access_list`.
+
 ### Calculating a refund of the charged priority fee
 
 Each transaction pays an individual `priorityFeePerGas` value and redistributing this part of the cold access cost
@@ -230,7 +240,8 @@
   for (let i = 0; i < sortedAccessDetails.length; i++) {
     const accessor = sortedAccessDetails[i]
     const refund = refunds.get(accessor.sender) ?? { refundFromBurn: 0n, refundFromCoinbase: 0n }
-    refund.refundFromBurn += BigInt(Math.floor(parseInt(accessGasCost) * parseInt(baseFeePerGas) * refundPercent))
+    const adjustedAccessGasCost = Math.max(MIN_ACCESS_LIST_ENTRY_COST, parseInt(accessGasCost) * refundPercent)
+    refund.refundFromBurn += BigInt(adjustedAccessGasCost * parseInt(baseFeePerGas))
     refund.refundFromCoinbase += BigInt(refundsFromCoinbase[i])
     refunds.set(accessor.sender, refund)
   }
@@ -263,7 +274,10 @@
   const refunds = [Math.floor(totalRefund * topTransactionContribution / totalContributions)]
   for (let i = 1; i < sortedAccesses.length; i++) {
     const charge = parseInt(sortedAccesses[i].priorityFeePerGas) * parseInt(accessGasCost)
-    refunds.push(Math.floor(totalRefund * charge / totalContributions))
+    const calldataCharge = parseInt(sortedAccesses[i].priorityFeePerGas) * MIN_ACCESS_LIST_ENTRY_COST
+    const refundToCalldata = charge - calldataCharge
+    const refundToContribution = Math.floor(totalRefund * charge / totalContributions)
+    refunds.push(Math.min(refundToCalldata, refundToContribution))
   }
   return refunds
 }
@@ -317,7 +331,7 @@
 
 ### Current cold storage gas cost is unfair
 
 As described in the [Motivation](#Motivation) section, the amount of gas that users spend on accessing the contract code does not reflect the actual cost of this access for the block builder or a validator.
 
 The more popular the contract code or a storage slot is, the more transactions in each block should share the cost. However, the current system multiplies the cost for the users instead of dividing it.
 
@@ -341,11 +355,11 @@
 This proposal does not introduce a change to any behavior that can be observed by a smart contract during its execution. The only effect this change has is a lower effective gas cost for the transaction senders.
 
 
 ## Test cases
 
 This repository contains all the test cases and related work:
 
 https://github.com/eth-infinitism/global-warming-test-cases
 
 ## Security Considerations