From 171531fbf1a308c1bf4d2f6b88c6ee6924657437 Mon Sep 17 00:00:00 2001
From: Etan Kissling <etan@nimbus.team>
Date: Tue, 15 Oct 2024 16:44:10 +0200
Subject: [PATCH] Add helper for recovering authority (#750)

For EIP-7702 SetCode transaction, it is necessary to identify the
authority issuing an authorization. Its account's code is set to
proxy to the authorization address if successful.
---
 eth/common/transactions_rlp.nim | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/eth/common/transactions_rlp.nim b/eth/common/transactions_rlp.nim
index 5812184..d0b85a4 100644
--- a/eth/common/transactions_rlp.nim
+++ b/eth/common/transactions_rlp.nim
@@ -305,6 +305,23 @@ proc readTxEip4844(rlp: var Rlp, tx: var Transaction) {.raises: [RlpError].} =
   rlp.read(tx.R)
   rlp.read(tx.S)
 
+func rlpEncodeEip7702(auth: Authorization): seq[byte] =
+  var w = initRlpWriter()
+  w.append(0x05'u8)
+  w.startList(3)
+  w.append(auth.chainId.uint64)
+  w.append(auth.address)
+  w.append(auth.nonce)
+  w.finish()
+
+func encodeForSigning*(auth: Authorization): seq[byte] =
+  ## Encode authorization data in preparation for signing or signature checking.
+  auth.rlpEncodeEip7702
+
+func rlpHashForSigning*(auth: Authorization): Hash32 =
+  # Hash authorization without signature
+  keccak256(encodeForSigning(auth))
+
 proc read*(rlp: var Rlp, T: type Authorization): T {.raises: [RlpError].} =
   rlp.tryEnterList()
   result.chainId = rlp.read(uint64).ChainId