101 lines
3.3 KiB
Go
101 lines
3.3 KiB
Go
// Copyright 2020 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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// signFile reads the contents of an input file and signs it (in armored format)
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// with the key provided, placing the signature into the output file.
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package signify
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import (
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"bytes"
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"crypto/ed25519"
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"encoding/base64"
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"errors"
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"fmt"
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"io/ioutil"
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"strings"
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"time"
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)
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var (
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errInvalidKeyHeader = errors.New("incorrect key header")
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errInvalidKeyLength = errors.New("invalid, key length != 104")
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)
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func parsePrivateKey(key string) (k ed25519.PrivateKey, header []byte, keyNum []byte, err error) {
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keydata, err := base64.StdEncoding.DecodeString(key)
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if err != nil {
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return nil, nil, nil, err
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}
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if len(keydata) != 104 {
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return nil, nil, nil, errInvalidKeyLength
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}
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if string(keydata[:2]) != "Ed" {
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return nil, nil, nil, errInvalidKeyHeader
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}
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return keydata[40:], keydata[:2], keydata[32:40], nil
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}
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// SignFile creates a signature of the input file.
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//
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// This accepts base64 keys in the format created by the 'signify' tool.
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// The signature is written to the 'output' file.
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func SignFile(input string, output string, key string, untrustedComment string, trustedComment string) error {
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// Pre-check comments and ensure they're set to something.
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if strings.IndexByte(untrustedComment, '\n') >= 0 {
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return errors.New("untrusted comment must not contain newline")
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}
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if strings.IndexByte(trustedComment, '\n') >= 0 {
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return errors.New("trusted comment must not contain newline")
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}
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if untrustedComment == "" {
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untrustedComment = "verify with " + input + ".pub"
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}
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if trustedComment == "" {
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trustedComment = fmt.Sprintf("timestamp:%d", time.Now().Unix())
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}
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filedata, err := ioutil.ReadFile(input)
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if err != nil {
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return err
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}
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skey, header, keyNum, err := parsePrivateKey(key)
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if err != nil {
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return err
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}
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// Create the main data signature.
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rawSig := ed25519.Sign(skey, filedata)
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var dataSig []byte
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dataSig = append(dataSig, header...)
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dataSig = append(dataSig, keyNum...)
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dataSig = append(dataSig, rawSig...)
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// Create the comment signature.
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var commentSigInput []byte
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commentSigInput = append(commentSigInput, rawSig...)
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commentSigInput = append(commentSigInput, []byte(trustedComment)...)
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commentSig := ed25519.Sign(skey, commentSigInput)
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// Create the output file.
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var out = new(bytes.Buffer)
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fmt.Fprintln(out, "untrusted comment:", untrustedComment)
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fmt.Fprintln(out, base64.StdEncoding.EncodeToString(dataSig))
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fmt.Fprintln(out, "trusted comment:", trustedComment)
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fmt.Fprintln(out, base64.StdEncoding.EncodeToString(commentSig))
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return ioutil.WriteFile(output, out.Bytes(), 0644)
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}
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