path: root/cmd/ethkey/message.go

// Copyright 2017 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// go-ethereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.

package main

import (
    "encoding/hex"
    "fmt"
    "io/ioutil"

    "github.com/ethereum/go-ethereum/accounts/keystore"
    "github.com/ethereum/go-ethereum/cmd/utils"
    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/crypto"
    "gopkg.in/urfave/cli.v1"
)

type outputSign struct {
    Signature string
}

var msgfileFlag = cli.StringFlag{
    Name:  "msgfile",
    Usage: "file containing the message to sign/verify",
}

var commandSignMessage = cli.Command{
    Name:      "signmessage",
    Usage:     "sign a message",
    ArgsUsage: "<keyfile> <message>",
    Description: `
Sign the message with a keyfile.

To sign a message contained in a file, use the --msgfile flag.
`,
    Flags: []cli.Flag{
        passphraseFlag,
        jsonFlag,
        msgfileFlag,
    },
    Action: func(ctx *cli.Context) error {
        message := getMessage(ctx, 1)

        // Load the keyfile.
        keyfilepath := ctx.Args().First()
        keyjson, err := ioutil.ReadFile(keyfilepath)
        if err != nil {
            utils.Fatalf("Failed to read the keyfile at '%s': %v", keyfilepath, err)
        }

        // Decrypt key with passphrase.
        passphrase := getPassphrase(ctx)
        key, err := keystore.DecryptKey(keyjson, passphrase)
        if err != nil {
            utils.Fatalf("Error decrypting key: %v", err)
        }

        signature, err := crypto.Sign(signHash(message), key.PrivateKey)
        if err != nil {
            utils.Fatalf("Failed to sign message: %v", err)
        }
        out := outputSign{Signature: hex.EncodeToString(signature)}
        if ctx.Bool(jsonFlag.Name) {
            mustPrintJSON(out)
        } else {
            fmt.Println("Signature:", out.Signature)
        }
        return nil
    },
}

type outputVerify struct {
    Success            bool
    RecoveredAddress   string
    RecoveredPublicKey string
}

var commandVerifyMessage = cli.Command{
    Name:      "verifymessage",
    Usage:     "verify the signature of a signed message",
    ArgsUsage: "<address> <signature> <message>",
    Description: `
Verify the signature of the message.
It is possible to refer to a file containing the message.`,
    Flags: []cli.Flag{
        jsonFlag,
        msgfileFlag,
    },
    Action: func(ctx *cli.Context) error {
        addressStr := ctx.Args().First()
        signatureHex := ctx.Args().Get(1)
        message := getMessage(ctx, 2)

        if !common.IsHexAddress(addressStr) {
            utils.Fatalf("Invalid address: %s", addressStr)
        }
        address := common.HexToAddress(addressStr)
        signature, err := hex.DecodeString(signatureHex)
        if err != nil {
            utils.Fatalf("Signature encoding is not hexadecimal: %v", err)
        }

        recoveredPubkey, err := crypto.SigToPub(signHash(message), signature)
        if err != nil || recoveredPubkey == nil {
            utils.Fatalf("Signature verification failed: %v", err)
        }
        recoveredPubkeyBytes := crypto.FromECDSAPub(recoveredPubkey)
        recoveredAddress := crypto.PubkeyToAddress(*recoveredPubkey)
        success := address == recoveredAddress

        out := outputVerify{
            Success:            success,
            RecoveredPublicKey: hex.EncodeToString(recoveredPubkeyBytes),
            RecoveredAddress:   recoveredAddress.Hex(),
        }
        if ctx.Bool(jsonFlag.Name) {
            mustPrintJSON(out)
        } else {
            if out.Success {
                fmt.Println("Signature verification successful!")
            } else {
                fmt.Println("Signature verification failed!")
            }
            fmt.Println("Recovered public key:", out.RecoveredPublicKey)
            fmt.Println("Recovered address:", out.RecoveredAddress)
        }
        return nil
    },
}

func getMessage(ctx *cli.Context, msgarg int) []byte {
    if file := ctx.String("msgfile"); file != "" {
        if len(ctx.Args()) > msgarg {
            utils.Fatalf("Can't use --msgfile and message argument at the same time.")
        }
        msg, err := ioutil.ReadFile(file)
        if err != nil {
            utils.Fatalf("Can't read message file: %v", err)
        }
        return msg
    } else if len(ctx.Args()) == msgarg+1 {
        return []byte(ctx.Args().Get(msgarg))
    }
    utils.Fatalf("Invalid number of arguments: want %d, got %d", msgarg+1, len(ctx.Args()))
    return nil
}