Util for removing EIP-191 prefix

packages/provider/src/transports/wallet-request-handler.ts

@@ -379,7 +379,9 @@ export class WalletRequestHandler implements ExternalProvider, JsonRpcHandler, P
           if (typeof typedDataObject === 'string') {
             try {
               typedData = JSON.parse(typedDataObject)
-            } catch (e) {}
+            } catch (e) {
+              console.warn('error parsing typedData', e)
+            }
           } else {
             typedData = typedDataObject
           }

packages/provider/src/utils.ts

@@ -23,6 +23,46 @@ export const prefixEIP191Message = (message: BytesLike): Uint8Array => {
   }
 }
 
+export const removeEIP191Prefix = (prefixedMessage: Uint8Array): Uint8Array => {
+  // If the message is not prefixed, we return the message as is.
+  if (JSON.stringify(prefixedMessage.slice(0, eip191prefix.length)) !== JSON.stringify(eip191prefix)) {
+    return prefixedMessage
+  }
+
+  // We have two parts to remove.
+  // First is the EIP-191 prefix.
+  const ethereumSignedMessagePartSlicedArray = prefixedMessage.slice(eip191prefix.length)
+
+  // Second is the digits added which represent length of the message without the prefix
+  // and we need to find the prefix that will match this.
+  // Here first we take the max prefix char length, and check if as a number it is bigger
+  // than the length of the message (since prefix is added to represent length of original message),
+  // if it is we we remove 1 from char length, if not we keep the max prefix char length.
+  // As an example for the case where , if the message is 123456789, the expected prefix char is 9, with starting value 9123456789
+  // the char length of the total message with the prefix is 10, so the max prefix char length we start is 2 from [1,0], and as a number 10, it is longer
+  // than the length of the message after removing prefix (10 - 2 = 8), so we slice 1 char less, which is 9, and we get the correct prefix.
+  const maxPrefixCharLength = String(ethereumSignedMessagePartSlicedArray.length).length
+
+  let prefixCharLenght: number
+  let prefixAsNumber: number
+
+  try {
+    prefixAsNumber = Number(ethers.utils.toUtf8String(ethereumSignedMessagePartSlicedArray.slice(0, maxPrefixCharLength)))
+  } catch {
+    prefixAsNumber = Number(ethers.utils.hexlify(ethereumSignedMessagePartSlicedArray.slice(0, maxPrefixCharLength)))
+  }
+
+  if (prefixAsNumber > ethereumSignedMessagePartSlicedArray.length) {
+    prefixCharLenght = maxPrefixCharLength - 1
+  } else {
+    prefixCharLenght = maxPrefixCharLength
+  }
+
+  const prefixRevertedMessage = ethereumSignedMessagePartSlicedArray.slice(prefixCharLenght)
+
+  return prefixRevertedMessage
+}
+
 export const isValidSignature = async (
   address: string,
   digest: Uint8Array,
@@ -34,6 +74,7 @@ export const isValidSignature = async (
   return reader.isValidSignature(address, digest, sig)
 }
 
+<<<<<<< Updated upstream
 // export const isValidMessageSignature = async (
 //   address: string,
 //   message: string | Uint8Array,
@@ -57,6 +98,31 @@ export const isValidSignature = async (
 // ): Promise<boolean> => {
 //   return isValidSignature(address, encodeTypedDataDigest(typedData), signature, provider, chainId, walletContext)
 // }
+=======
+export const isValidMessageSignature = async (
+  address: string,
+  message: string | Uint8Array,
+  signature: string,
+  provider: Web3Provider | ethers.providers.Web3Provider | ethers.providers.Provider,
+  chainId?: number,
+  walletContext?: WalletContext
+): Promise<boolean> => {
+  const prefixed = prefixEIP191Message(message)
+  const digest = encodeMessageDigest(prefixed)
+  return isValidSignature(address, digest, signature, provider, chainId, walletContext)
+}
+
+export const isValidTypedDataSignature = (
+  address: string,
+  typedData: TypedData,
+  signature: string,
+  provider: Web3Provider | ethers.providers.Web3Provider | ethers.providers.Provider,
+  chainId?: number,
+  walletContext?: WalletContext
+): Promise<boolean> => {
+  return isValidSignature(address, encodeTypedDataDigest(typedData), signature, provider, chainId, walletContext)
+}
+>>>>>>> Stashed changes
 
 // export const recoverWalletConfig = async (
 //   address: string,

packages/provider/tests/messages.ts

@@ -1,15 +1,17 @@
 import { ethers } from 'ethers'
+import { prefixEIP191Message } from '../src/utils'
 
 // Ethereum personal sign: Hello, World!
 export const message1 = new Uint8Array([
   25, 69, 116, 104, 101, 114, 101, 117, 109, 32, 83, 105, 103, 110, 101, 100, 32, 77, 101, 115, 115, 97, 103, 101, 58, 10, 49, 51,
   72, 101, 108, 108, 111, 44, 32, 87, 111, 114, 108, 100, 33
 ])
 
-
-export const dclLogin = ethers.utils.toUtf8Bytes(`Decentraland Login
+const dlcText = `Decentraland Login
 Ephemeral address: 0xe1bCF3CAc83534a055f7254C1FD88B21159fCc67
-Expiration: 2022-10-27T16:03:29.191Z`)
+Expiration: 2022-10-27T16:03:29.191Z`
+
+export const dclLogin = ethers.utils.toUtf8Bytes(dlcText)
 
 // Ethereum personal sign 0x v3 order
 export const zeroExV3Order = new Uint8Array([
@@ -47,3 +49,43 @@ export const zeroExV3Order = new Uint8Array([
   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 ])
+
+// Messages for testing remove-iep191prefix
+
+export const removeIep191Prefix_test1_raw = `1915 Robert Frost
+The Road Not Taken
+  
+Two roads diverged in a yellow wood,
+And sorry I could not travel both
+And be one traveler, long I stood
+And looked down one as far as I could
+To where it bent in the undergrowth
+  
+Then took the other, as just as fair,
+And having perhaps the better claim,
+Because it was grassy and wanted wear
+Though as for that the passing there
+Had worn them really about the same,
+  
+And both that morning equally lay
+In leaves no step had trodden black.
+Oh, I kept the first for another day!
+Yet knowing how way leads on to way,
+I doubted if I should ever come back.
+  
+I shall be telling this with a sigh
+Somewhere ages and ages hence:
+Two roads diverged in a wood, and I—
+I took the one less traveled by,
+And that has made all the difference.
+  
+\u2601 \u2600 \u2602`
+export const removeIep191Prefix_test2_raw = dlcText
+export const removeIep191Prefix_test3_raw = '1915 Robe' // 9 chars
+export const removeIep191Prefix_test4_raw =
+  '123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789' // 99 chars
+
+export const removeIep191Prefix_test1_prefixed = prefixEIP191Message(removeIep191Prefix_test1_raw)
+export const removeIep191Prefix_test2_prefixed = prefixEIP191Message(dlcText)
+export const removeIep191Prefix_test3_prefixed = prefixEIP191Message(removeIep191Prefix_test3_raw)
+export const removeIep191Prefix_test4_prefixed = prefixEIP191Message(removeIep191Prefix_test4_raw)

packages/provider/tests/remove-eip191prefix.spec.ts

@@ -0,0 +1,31 @@
+import chaiAsPromised from 'chai-as-promised'
+import * as chai from 'chai'
+
+import {
+  removeIep191Prefix_test1_prefixed,
+  removeIep191Prefix_test1_raw,
+  removeIep191Prefix_test2_prefixed,
+  removeIep191Prefix_test2_raw,
+  removeIep191Prefix_test3_prefixed,
+  removeIep191Prefix_test3_raw,
+  removeIep191Prefix_test4_prefixed,
+  removeIep191Prefix_test4_raw
+} from './messages'
+import { removeEIP191Prefix } from '../src/utils'
+import { ethers } from 'ethers'
+const { expect } = chai.use(chaiAsPromised)
+
+describe('removing eip191prefix', () => {
+  it('should remove prefix', () => {
+    expect(ethers.utils.toUtf8String(removeEIP191Prefix(removeIep191Prefix_test1_prefixed))).equal(removeIep191Prefix_test1_raw)
+  })
+
+  it('should handle eip191 exempt messages (by returning early)', () => {
+    expect(ethers.utils.toUtf8String(removeEIP191Prefix(removeIep191Prefix_test2_prefixed))).equal(removeIep191Prefix_test2_raw)
+  })
+
+  it('should remove prefix for case where max prefix char as number is bigger than the length of the message', () => {
+    expect(ethers.utils.toUtf8String(removeEIP191Prefix(removeIep191Prefix_test3_prefixed))).equal(removeIep191Prefix_test3_raw)
+    expect(ethers.utils.toUtf8String(removeEIP191Prefix(removeIep191Prefix_test4_prefixed))).equal(removeIep191Prefix_test4_raw)
+  })
+})