Create ReformatLedgerTx to reformat EIP-712 payloads

ethereum/eip712/ledgerReformat.go

@@ -0,0 +1,75 @@
+package eip712
+
+import (
+	"fmt"
+
+	"github.com/cosmos/cosmos-sdk/client"
+	codectypes "github.com/cosmos/cosmos-sdk/codec/types"
+	cosmoskr "github.com/cosmos/cosmos-sdk/crypto/keyring"
+	"github.com/cosmos/cosmos-sdk/types/tx/signing"
+	authtx "github.com/cosmos/cosmos-sdk/x/auth/tx"
+	"github.com/evmos/ethermint/types"
+)
+
+// ReformatLedgerTx reformats Ledger-signed Cosmos transactions to match the fork expected by Evmos
+// by including the signature in a Web3Tx extension.
+func ReformatLedgerTx(chainID string, keyType cosmoskr.KeyType, txBuilder client.TxBuilder) error {
+	if keyType != cosmoskr.TypeLedger {
+		// Only process Ledger transactions
+		return nil
+	}
+
+	// Init extension builder to set Web3 extension
+	extensionBuilder, ok := txBuilder.(authtx.ExtensionOptionsTxBuilder)
+	if !ok {
+		return fmt.Errorf("Error setting extension options: cannot cast to ExtensionOptionsTxBuilder")
+	}
+
+	// Get signatures from TxBuilder
+	sigs, err := txBuilder.GetTx().GetSignaturesV2()
+	if err != nil {
+		return fmt.Errorf("Could not get signatures with error: %w", err)
+	}
+
+	// Verify single-signer
+	if len(sigs) != 1 {
+		return fmt.Errorf("Invalid number of signatures, expected 1 and got %v", len(sigs))
+	}
+
+	signature := sigs[0]
+	sigBytes := signature.Data.(*signing.SingleSignatureData).Signature
+
+	// Parse Chain ID as big.Int
+	chainIDInt, err := types.ParseChainID(chainID)
+	if err != nil {
+		return fmt.Errorf("Error parsing chain id: %v\n", err)
+	}
+
+	// Add ExtensionOptionsWeb3Tx extension with signature
+	var option *codectypes.Any
+	option, err = codectypes.NewAnyWithValue(&types.ExtensionOptionsWeb3Tx{
+		FeePayer:         signature.PubKey.Address().String(),
+		TypedDataChainID: chainIDInt.Uint64(),
+		FeePayerSig:      sigBytes,
+	})
+	extensionBuilder.SetExtensionOptions(option)
+
+	// Set signature data with to indicate Amino Sign Type
+	// (Regardless of input signMode, Evmos requires Amino signature type for Ledger)
+	blankSig := signing.SingleSignatureData{
+		SignMode:  signing.SignMode_SIGN_MODE_LEGACY_AMINO_JSON,
+		Signature: nil,
+	}
+	sig := signing.SignatureV2{
+		PubKey:   signature.PubKey,
+		Data:     &blankSig,
+		Sequence: signature.Sequence,
+	}
+
+	err = txBuilder.SetSignatures(sig)
+	if err != nil {
+		return fmt.Errorf("Unable to set signatures on payload: %v\n", err)
+	}
+
+	return nil
+}