EIP-7883: ModExp gas cost increase (#4071)

* Increase minimal price from 200 to 500

* Increase cost when exponent is larger than 32 bytes

* Multiplication complexity is doubled if base or modulus is bigger than 32 bytes

* Add 7883 to common

* Update implementation to allow 2565 and pre-2565 gas algorithm

Author: am1r021

packages/common/src/eips.ts

@@ -478,4 +478,12 @@ export const eipsDict: EIPsDict = {
   7864: {
     minimumHardfork: Hardfork.London,
   },
+  /**
+   * Description : EIP-7883: ModExp Gas Cost Increase
+   * URL         : hhttps://eips.ethereum.org/EIPS/eip-7883
+   * Status      : Draft
+   */
+  7883: {
+    minimumHardfork: Hardfork.Chainstart,
+  },
 }

packages/common/src/hardforks.ts

@@ -166,7 +166,7 @@ export const hardforksDict: HardforksDict = {
    * Status     : Final
    */
   osaka: {
-    eips: [663, 3540, 3670, 4200, 4750, 5450, 6206, 7069, 7480, 7620, 7692, 7698],
+    eips: [663, 3540, 3670, 4200, 4750, 5450, 6206, 7069, 7480, 7620, 7692, 7698, 7883],
   },
   /**
    * Description: Next feature hardfork after osaka, internally used for verkle testing/implementation (incomplete/experimental)

packages/evm/src/precompiles/05-modexp.ts

@@ -24,8 +24,9 @@ import type { PrecompileInput } from './types.ts'
 
 const BIGINT_4 = BigInt(4)
 const BIGINT_16 = BigInt(16)
-const BIGINT_200 = BigInt(200)
 const BIGINT_480 = BigInt(480)
+const BIGINT_200 = BigInt(200)
+const BIGINT_500 = BigInt(500)
 const BIGINT_1024 = BigInt(1024)
 const BIGINT_3072 = BigInt(3072)
 const BIGINT_199680 = BigInt(199680)
@@ -56,7 +57,7 @@ function multiplicationComplexityEIP2565(x: bigint): bigint {
   return words * words
 }
 
-function getAdjustedExponentLength(data: Uint8Array): bigint {
+function getAdjustedExponentLength(data: Uint8Array, opts: PrecompileInput): bigint {
   let expBytesStart
   try {
     const baseLen = bytesToBigInt(data.subarray(0, 32))
@@ -83,8 +84,8 @@ function getAdjustedExponentLength(data: Uint8Array): bigint {
   if (expLenMinus32OrZero < BIGINT_0) {
     expLenMinus32OrZero = BIGINT_0
   }
-  const eightTimesExpLenMinus32OrZero = expLenMinus32OrZero * BIGINT_8
-  let adjustedExpLen = eightTimesExpLenMinus32OrZero
+  let adjustedExpLen =
+    expLenMinus32OrZero * (opts.common.isActivatedEIP(7883) === true ? BIGINT_16 : BIGINT_8)
   if (bitLen > 0) {
     adjustedExpLen += BigInt(bitLen)
   }
@@ -108,7 +109,7 @@ export function precompile05(opts: PrecompileInput): ExecResult {
   const pName = getPrecompileName('05')
   const data = opts.data.length < 96 ? setLengthRight(opts.data, 96) : opts.data
 
-  let adjustedELen = getAdjustedExponentLength(data)
+  let adjustedELen = getAdjustedExponentLength(data, opts)
   if (adjustedELen < BIGINT_1) {
     adjustedELen = BIGINT_1
   }
@@ -131,13 +132,19 @@ export function precompile05(opts: PrecompileInput): ExecResult {
   const mStart = eEnd
   const mEnd = mStart + mLen
 
-  if (!opts.common.isActivatedEIP(2565)) {
-    gasUsed = (adjustedELen * multiplicationComplexity(maxLen)) / Gquaddivisor
-  } else {
+  if (opts.common.isActivatedEIP(7883)) {
+    const wordsSquared = multiplicationComplexityEIP2565(maxLen)
+    gasUsed = (adjustedELen * (maxLen > 32 ? 2n * wordsSquared : wordsSquared)) / Gquaddivisor
+    if (gasUsed < BIGINT_500) {
+      gasUsed = BIGINT_500
+    }
+  } else if (opts.common.isActivatedEIP(2565)) {
     gasUsed = (adjustedELen * multiplicationComplexityEIP2565(maxLen)) / Gquaddivisor
     if (gasUsed < BIGINT_200) {
       gasUsed = BIGINT_200
     }
+  } else {
+    gasUsed = (adjustedELen * multiplicationComplexity(maxLen)) / Gquaddivisor
   }
   if (!gasLimitCheck(opts, gasUsed, pName)) {
     return OOGResult(opts.gasLimit)