Update AccCreationAuth signature hash to EIP-712

Compatible with `hermeznetwork/contracts` commit: `67726208723a40f2251953aaabf4d2b6221f8b13`
Compatible with `hermeznetwork/commonjs` commit: `dee266fb036a64bebc65756ebd5f0361929c110d`

common/accountcreationauths.go

@@ -1,21 +1,25 @@
 package common
 
 import (
-	"encoding/binary"
-	"strconv"
 	"time"
 
 	ethCommon "github.com/ethereum/go-ethereum/common"
+	ethMath "github.com/ethereum/go-ethereum/common/math"
 	ethCrypto "github.com/ethereum/go-ethereum/crypto"
+	ethSigner "github.com/ethereum/go-ethereum/signer/core"
+	"github.com/hermeznetwork/tracerr"
 	"github.com/iden3/go-iden3-crypto/babyjub"
 )
 
 // AccountCreationAuthMsg is the message that is signed to authorize a Hermez
 // account creation
-const AccountCreationAuthMsg = "I authorize this babyjubjub key for hermez rollup account creation"
+const AccountCreationAuthMsg = "Account creation"
 
-// EthMsgPrefix is the prefix for message signing at the Ethereum ecosystem
-const EthMsgPrefix = "\x19Ethereum Signed Message:\n"
+// EIP712Version is the used version of the EIP-712
+const EIP712Version = "1"
+
+// EIP712Provider defines the Provider for the EIP-712
+const EIP712Provider = "Hermez Network"
 
 var (
 	// EmptyEthSignature is an ethereum signature of all zeroes
@@ -31,27 +35,64 @@ type AccountCreationAuth struct {
 	Timestamp time.Time             `meddler:"timestamp,utctime"`
 }
 
+// toHash returns a byte array to be hashed from the AccountCreationAuth, which
+// follows the EIP-712 encoding
 func (a *AccountCreationAuth) toHash(chainID uint16,
-	hermezContractAddr ethCommon.Address) []byte {
-	var chainIDBytes [2]byte
-	binary.BigEndian.PutUint16(chainIDBytes[:], chainID)
-	// [EthPrefix | AccountCreationAuthMsg | compressedBJJ | chainID | hermezContractAddr]
-	var b []byte
-	b = append(b, []byte(AccountCreationAuthMsg)...)
-	b = append(b, SwapEndianness(a.BJJ[:])...) // for js implementation compatibility
-	b = append(b, chainIDBytes[:]...)
-	b = append(b, hermezContractAddr[:]...)
-
-	ethPrefix := EthMsgPrefix + strconv.Itoa(len(b))
-	return append([]byte(ethPrefix), b...)
+	hermezContractAddr ethCommon.Address) ([]byte, error) {
+	chainIDFormatted := ethMath.NewHexOrDecimal256(int64(chainID))
+
+	signerData := ethSigner.TypedData{
+		Types: ethSigner.Types{
+			"EIP712Domain": []ethSigner.Type{
+				{Name: "name", Type: "string"},
+				{Name: "version", Type: "string"},
+				{Name: "chainId", Type: "uint256"},
+				{Name: "verifyingContract", Type: "address"},
+			},
+			"Authorise": []ethSigner.Type{
+				{Name: "Provider", Type: "string"},
+				{Name: "Authorisation", Type: "string"},
+				{Name: "BJJKey", Type: "bytes32"},
+			},
+		},
+		PrimaryType: "Authorise",
+		Domain: ethSigner.TypedDataDomain{
+			Name:              EIP712Provider,
+			Version:           EIP712Version,
+			ChainId:           chainIDFormatted,
+			VerifyingContract: hermezContractAddr.Hex(),
+		},
+		Message: ethSigner.TypedDataMessage{
+			"Provider":      EIP712Provider,
+			"Authorisation": AccountCreationAuthMsg,
+			"BJJKey":        SwapEndianness(a.BJJ[:]),
+		},
+	}
+
+	domainSeparator, err := signerData.HashStruct("EIP712Domain", signerData.Domain.Map())
+	if err != nil {
+		return nil, tracerr.Wrap(err)
+	}
+	typedDataHash, err := signerData.HashStruct(signerData.PrimaryType, signerData.Message)
+	if err != nil {
+		return nil, tracerr.Wrap(err)
+	}
+
+	rawData := []byte{0x19, 0x01} // "\x19\x01"
+	rawData = append(rawData, domainSeparator...)
+	rawData = append(rawData, typedDataHash...)
+	return rawData, nil
 }
 
 // HashToSign returns the hash to be signed by the Etherum address to authorize
-// the account creation
+// the account creation, which follows the EIP-712 encoding
 func (a *AccountCreationAuth) HashToSign(chainID uint16,
 	hermezContractAddr ethCommon.Address) ([]byte, error) {
-	b := a.toHash(chainID, hermezContractAddr)
-	return ethCrypto.Keccak256Hash(b).Bytes(), nil
+	b, err := a.toHash(chainID, hermezContractAddr)
+	if err != nil {
+		return nil, tracerr.Wrap(err)
+	}
+	return ethCrypto.Keccak256(b), nil
 }
 
 // Sign signs the account creation authorization message using the provided
@@ -59,16 +100,17 @@ func (a *AccountCreationAuth) HashToSign(chainID uint16,
 // should do an ethereum signature using the account corresponding to
 // `a.EthAddr`.  The `signHash` function is used to make signig flexible: in
 // tests we sign directly using the private key, outside tests we sign using
-// the keystore (which never exposes the private key).
+// the keystore (which never exposes the private key). Sign follows the EIP-712
+// encoding.
 func (a *AccountCreationAuth) Sign(signHash func(hash []byte) ([]byte, error),
 	chainID uint16, hermezContractAddr ethCommon.Address) error {
 	hash, err := a.HashToSign(chainID, hermezContractAddr)
 	if err != nil {
-		return err
+		return tracerr.Wrap(err)
 	}
 	sig, err := signHash(hash)
 	if err != nil {
-		return err
+		return tracerr.Wrap(err)
 	}
 	sig[64] += 27
 	a.Signature = sig
@@ -77,7 +119,8 @@ func (a *AccountCreationAuth) Sign(signHash func(hash []byte) ([]byte, error),
 }
 
 // VerifySignature ensures that the Signature is done with the EthAddr, for the
-// chainID and hermezContractAddress passed by parameter
+// chainID and hermezContractAddress passed by parameter. VerifySignature
+// follows the EIP-712 encoding.
 func (a *AccountCreationAuth) VerifySignature(chainID uint16,
 	hermezContractAddr ethCommon.Address) bool {
 	// Calculate hash to be signed

common/accountcreationauths_test.go

@@ -39,7 +39,7 @@ func TestAccountCreationAuthSignVerify(t *testing.T) {
 	// Hash and sign manually and compare the generated signature
 	hash, err := a.HashToSign(chainID, hermezContractAddr)
 	require.NoError(t, err)
-	assert.Equal(t, "4f8df75e96fdce1ac90bb2f8d81c42047600f85bfcef80ce3b91c2a2afc58c1e",
+	assert.Equal(t, "9414667457e658dd31949b82996b75c65a055512244c3bbfd22ff56add02ba65",
 		hex.EncodeToString(hash))
 	sig, err := ethCrypto.Sign(hash, ethSk)
 	require.NoError(t, err)
@@ -75,9 +75,9 @@ func TestAccountCreationAuthJSComp(t *testing.T) {
 		pkCompStr:          "21b0a1688b37f77b1d1d5539ec3b826db5ac78b2513f574a04c50a7d4f8246d7",
 		chainID:            uint16(4),
 		hermezContractAddr: "0x7e5f4552091a69125d5dfcb7b8c2659029395bdf",
-		toHashExpected:     "19457468657265756d205369676e6564204d6573736167653a0a3132304920617574686f72697a65207468697320626162796a75626a7562206b657920666f72206865726d657a20726f6c6c7570206163636f756e74206372656174696f6e21b0a1688b37f77b1d1d5539ec3b826db5ac78b2513f574a04c50a7d4f8246d700047e5f4552091a69125d5dfcb7b8c2659029395bdf",
-		hashExpected:       "39afea52d843a4de905b6b5ebb0ee8c678141f711d96d9b429c4aec10ef9911f",
-		sigExpected:        "73d10d6ecf06ee8a5f60ac90f06b78bef9c650f414ba3ac73e176dc32e896159147457e9c86f0b4bd60fdaf2c0b2aec890a7df993d69a4805e242a6b845ebf231c",
+		toHashExpected:     "190189658bba487e11c7da602676ee32bc90b77d3f32a305b147e4f3c3b35f19672e5d84ccc38d0ab245c469b719549d837113465c2abf9972c49403ca6fd10ed3dc",
+		hashExpected:       "c56eba41e511df100c804c5c09288f35887efea4f033be956481af335df3bea2",
+		sigExpected:        "dbedcc5ce02db8f48afbdb2feba9a3a31848eaa8fca5f312ce37b01db45d2199208335330d4445bd2f51d1db68dbc0d0bf3585c4a07504b4efbe46a69eaae5a21b",
 	}
 	tv1 := testVector{
 		ethSk:              "0000000000000000000000000000000000000000000000000000000000000002",
@@ -85,9 +85,9 @@ func TestAccountCreationAuthJSComp(t *testing.T) {
 		pkCompStr:          "093985b1993d9f743f9d7d943ed56f38601cb8b196db025f79650c4007c3054d",
 		chainID:            uint16(0),
 		hermezContractAddr: "0x2b5ad5c4795c026514f8317c7a215e218dccd6cf",
-		toHashExpected:     "19457468657265756d205369676e6564204d6573736167653a0a3132304920617574686f72697a65207468697320626162796a75626a7562206b657920666f72206865726d657a20726f6c6c7570206163636f756e74206372656174696f6e093985b1993d9f743f9d7d943ed56f38601cb8b196db025f79650c4007c3054d00002b5ad5c4795c026514f8317c7a215e218dccd6cf",
-		hashExpected:       "89a3895993a4736232212e59566294feb3da227af44375daf3307dcad5451d5d",
-		sigExpected:        "bb4156156c705494ad5f99030342c64657e51e2994750f92125717c40bf56ad632044aa6bd00979feea92c417b552401e65fe5f531f15010d9d1c278da8be1df1b",
+		toHashExpected:     "1901dafbc253dedf90d6421dc6e25d5d9efc6985133cb2a8d363d0a081a0e3eddddc65f603a88de36aaeabd3b4cf586538c7f3fd50c94780530a3707c8c14ad9fd11",
+		hashExpected:       "deb9afa479282cf27b442ce8ba86b19448aa87eacef691521a33db5d0feb9959",
+		sigExpected:        "6a0da90ba2d2b1be679a28ebe54ee03082d44b836087391cd7d2607c1e4dafe04476e6e88dccb8707c68312512f16c947524b35c80f26c642d23953e9bb84c701c",
 	}
 	tv2 := testVector{
 		ethSk:              "c5e8f61d1ab959b397eecc0a37a6517b8e67a0e7cf1f4bce5591f3ed80199122",
@@ -95,9 +95,9 @@ func TestAccountCreationAuthJSComp(t *testing.T) {
 		pkCompStr:          "22870c1bcc451396202d62f566026eab8e438c6c91decf8ddf63a6c162619b52",
 		chainID:            uint16(31337), // =0x7a69
 		hermezContractAddr: "0xf4e77E5Da47AC3125140c470c71cBca77B5c638c",
-		toHashExpected:     "19457468657265756d205369676e6564204d6573736167653a0a3132304920617574686f72697a65207468697320626162796a75626a7562206b657920666f72206865726d657a20726f6c6c7570206163636f756e74206372656174696f6e22870c1bcc451396202d62f566026eab8e438c6c91decf8ddf63a6c162619b527a69f4e77e5da47ac3125140c470c71cbca77b5c638c",
-		hashExpected:       "4f6ead01278ba4597d4720e37482f585a713497cea994a95209f4c57a963b4a7",
-		sigExpected:        "43b5818802a137a72a190c1d8d767ca507f7a4804b1b69b5e055abf31f4f2b476c80bb1ba63260d95610f6f831420d32130e7f22fec5d76e16644ddfcedd0d441c",
+		toHashExpected:     "190167617949b934d7e01add4009cd3d47415a26727b7d6288e5dce33fb3721d5a1a9ce511b19b694c9aaf8183f4987ed752f24884c54c003d11daa2e98c7547a79e",
+		hashExpected:       "157b570c597e615b8356ce008ac39f43bc9b6d50080bc07d968031b9378acbbb",
+		sigExpected:        "a0766181102428b5672e523dc4b905c10ddf025c10dbd0b3534ef864632a14652737610041c670b302fc7dca28edd5d6eac42b72d69ce58da8ce21287b244e381b",
 	}
 	tvs = append(tvs, tv0)
 	tvs = append(tvs, tv1)
@@ -122,10 +122,10 @@ func TestAccountCreationAuthJSComp(t *testing.T) {
 			BJJ:     pkComp,
 		}
 
-		toHash := a.toHash(chainID, hermezContractAddr)
+		toHash, err := a.toHash(chainID, hermezContractAddr)
+		require.NoError(t, err)
 		assert.Equal(t, tv.toHashExpected,
 			hex.EncodeToString(toHash))
-		assert.Equal(t, 120+len(EthMsgPrefix)+len([]byte("120")), len(toHash))
 
 		msg, err := a.HashToSign(chainID, hermezContractAddr)
 		require.NoError(t, err)