plugeth/crypto/signify/signify.go

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// Copyright 2020 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
// signFile reads the contents of an input file and signs it (in armored format)
// with the key provided, placing the signature into the output file.
package signify
import (
"bytes"
"crypto/ed25519"
"encoding/base64"
"errors"
"fmt"
"io/ioutil"
"strings"
"time"
)
var (
errInvalidKeyHeader = errors.New("incorrect key header")
errInvalidKeyLength = errors.New("invalid, key length != 104")
)
func parsePrivateKey(key string) (k ed25519.PrivateKey, header []byte, keyNum []byte, err error) {
keydata, err := base64.StdEncoding.DecodeString(key)
if err != nil {
return nil, nil, nil, err
}
if len(keydata) != 104 {
return nil, nil, nil, errInvalidKeyLength
}
if string(keydata[:2]) != "Ed" {
return nil, nil, nil, errInvalidKeyHeader
}
return ed25519.PrivateKey(keydata[40:]), keydata[:2], keydata[32:40], nil
}
// SignFile creates a signature of the input file.
//
// This accepts base64 keys in the format created by the 'signify' tool.
// The signature is written to the 'output' file.
func SignFile(input string, output string, key string, untrustedComment string, trustedComment string) error {
// Pre-check comments and ensure they're set to something.
if strings.IndexByte(untrustedComment, '\n') >= 0 {
return errors.New("untrusted comment must not contain newline")
}
if strings.IndexByte(trustedComment, '\n') >= 0 {
return errors.New("trusted comment must not contain newline")
}
if untrustedComment == "" {
untrustedComment = "verify with " + input + ".pub"
}
if trustedComment == "" {
trustedComment = fmt.Sprintf("timestamp:%d", time.Now().Unix())
}
filedata, err := ioutil.ReadFile(input)
if err != nil {
return err
}
skey, header, keyNum, err := parsePrivateKey(key)
if err != nil {
return err
}
// Create the main data signature.
rawSig := ed25519.Sign(skey, filedata)
var dataSig []byte
dataSig = append(dataSig, header...)
dataSig = append(dataSig, keyNum...)
dataSig = append(dataSig, rawSig...)
// Create the comment signature.
var commentSigInput []byte
commentSigInput = append(commentSigInput, rawSig...)
commentSigInput = append(commentSigInput, []byte(trustedComment)...)
commentSig := ed25519.Sign(skey, commentSigInput)
// Create the output file.
var out = new(bytes.Buffer)
fmt.Fprintln(out, "untrusted comment:", untrustedComment)
fmt.Fprintln(out, base64.StdEncoding.EncodeToString(dataSig))
fmt.Fprintln(out, "trusted comment:", trustedComment)
fmt.Fprintln(out, base64.StdEncoding.EncodeToString(commentSig))
return ioutil.WriteFile(output, out.Bytes(), 0644)
}