forked from sassoftware/relic
/
signer.go
219 lines (204 loc) · 5.95 KB
/
signer.go
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//
// Copyright (c) SAS Institute Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
package pgp
// Sign arbitrary data using PGP detached or cleartext signatures
import (
"bufio"
"bytes"
"errors"
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"time"
"github.com/sassoftware/relic/lib/atomicfile"
"github.com/sassoftware/relic/lib/certloader"
"github.com/sassoftware/relic/lib/magic"
"github.com/sassoftware/relic/lib/pgptools"
"github.com/sassoftware/relic/signers"
"golang.org/x/crypto/openpgp"
"golang.org/x/crypto/openpgp/armor"
"golang.org/x/crypto/openpgp/packet"
)
var PgpSigner = &signers.Signer{
Name: "pgp",
Magic: magic.FileTypePGP,
CertTypes: signers.CertTypePgp,
AllowStdin: true,
Transform: transform,
Sign: sign,
VerifyStream: verify,
}
const maxStreamClearSignSize = 10 * 1000 * 1000
func init() {
PgpSigner.Flags().BoolP("armor", "a", false, "(PGP) Create ASCII armored output")
PgpSigner.Flags().Bool("inline", false, "(PGP) Create a signed message instead of a detached signature")
PgpSigner.Flags().Bool("clearsign", false, "(PGP) Create a cleartext signature")
PgpSigner.Flags().BoolP("textmode", "t", false, "(PGP) Sign in CRLF canonical text form")
// for compat with 2.0 clients
PgpSigner.Flags().String("pgp", "", "")
PgpSigner.Flags().MarkHidden("pgp")
signers.Register(PgpSigner)
}
type pgpTransformer struct {
inline, clearsign, armor bool
filename string
stream io.ReadSeeker
closer io.Closer
}
func transform(f *os.File, opts signers.SignOpts) (signers.Transformer, error) {
armor := opts.Flags.GetBool("armor")
inline := opts.Flags.GetBool("inline")
if inline {
// always get a non-armored sig from the server
opts.Flags.Values["armor"] = "false"
}
clearsign := opts.Flags.GetBool("clearsign")
stream := io.ReadSeeker(f)
if _, err := f.Seek(0, 0); err != nil {
// not seekable so consume it all now
contents, err := ioutil.ReadAll(io.LimitReader(stream, maxStreamClearSignSize))
if err != nil {
return nil, err
} else if len(contents) == maxStreamClearSignSize {
return nil, errors.New("input stream is too big, try writing it to file first")
}
stream = bytes.NewReader(contents)
}
return &pgpTransformer{
inline: inline,
clearsign: clearsign,
armor: armor,
filename: filepath.Base(f.Name()),
stream: stream,
closer: f,
}, nil
}
func (t *pgpTransformer) GetReader() (io.Reader, error) {
if _, err := t.stream.Seek(0, 0); err != nil {
return nil, err
}
return t.stream, nil
}
func sign(r io.Reader, cert *certloader.Certificate, opts signers.SignOpts) ([]byte, error) {
armor := opts.Flags.GetBool("armor")
clearsign := opts.Flags.GetBool("clearsign")
textmode := opts.Flags.GetBool("textmode")
if pgpcompat := opts.Flags.GetString("pgp"); pgpcompat == "mini-clear" {
clearsign = true
}
var sf func(io.Writer, *openpgp.Entity, io.Reader, *packet.Config) error
if clearsign {
sf = pgptools.DetachClearSign
} else if armor {
if textmode {
sf = openpgp.ArmoredDetachSignText
} else {
sf = openpgp.ArmoredDetachSign
}
} else {
if textmode {
sf = openpgp.DetachSignText
} else {
sf = openpgp.DetachSign
}
}
var buf bytes.Buffer
config := &packet.Config{
DefaultHash: opts.Hash,
Time: func() time.Time { return opts.Time },
}
if err := sf(&buf, cert.PgpKey, r, config); err != nil {
return nil, err
} else if armor {
buf.WriteByte('\n')
}
return buf.Bytes(), nil
}
func (t *pgpTransformer) Apply(dest, mimeType string, result io.Reader) error {
outfile, err := atomicfile.WriteAny(dest)
if err != nil {
return err
}
defer outfile.Close()
if t.inline || t.clearsign {
// reassemble signature
if _, err := t.stream.Seek(0, 0); err != nil {
return err
}
sig, err := ioutil.ReadAll(result)
if err != nil {
return err
}
if t.clearsign {
err = pgptools.MergeClearSign(outfile, sig, t.stream)
} else {
err = pgptools.MergeSignature(outfile, sig, t.stream, t.armor, t.filename)
}
if err != nil {
return err
}
} else {
if _, err := io.Copy(outfile, result); err != nil {
return err
}
}
t.closer.Close()
return outfile.Commit()
}
func verify(r io.Reader, opts signers.VerifyOpts) ([]*signers.Signature, error) {
br := bufio.NewReader(r)
// remove ASCII armor
reader := io.Reader(br)
if x, _ := br.Peek(34); len(x) >= 1 && x[0] == '-' {
if bytes.HasPrefix(x, []byte("-----BEGIN PGP SIGNED MESSAGE-----")) {
// clearsign
sig, err := pgptools.VerifyClearSign(reader, nil, opts.TrustedPgp)
return verifyPgp(sig, opts.FileName, err)
}
block, err := armor.Decode(reader)
if err != nil {
return nil, err
}
reader = block.Body
}
if opts.Content != "" {
// detached signature
fc, err := os.Open(opts.Content)
if err != nil {
return nil, err
}
defer fc.Close()
sig, err := pgptools.VerifyDetached(reader, fc, opts.TrustedPgp)
return verifyPgp(sig, opts.FileName, err)
}
// inline signature
sig, err := pgptools.VerifyInline(reader, nil, opts.TrustedPgp)
return verifyPgp(sig, opts.FileName, err)
}
func verifyPgp(sig *pgptools.PgpSignature, name string, err error) ([]*signers.Signature, error) {
if err == nil {
return []*signers.Signature{&signers.Signature{
CreationTime: sig.CreationTime,
Hash: sig.Hash,
SignerPgp: sig.Key.Entity,
}}, nil
} else if sig != nil {
return nil, fmt.Errorf("bad signature from %s(%x) [%s]: %s", pgptools.EntityName(sig.Key.Entity), sig.Key.PublicKey.KeyId, sig.CreationTime, err)
}
return nil, err
}