github.com/olivere/camlistore@v0.0.0-20140121221811-1b7ac2da0199/pkg/jsonsign/sign_normal.go (about)

     1  // +build !appengine
     2  
     3  /*
     4  Copyright 2013 Google Inc.
     5  
     6  Licensed under the Apache License, Version 2.0 (the "License");
     7  you may not use this file except in compliance with the License.
     8  You may obtain a copy of the License at
     9  
    10       http://www.apache.org/licenses/LICENSE-2.0
    11  
    12  Unless required by applicable law or agreed to in writing, software
    13  distributed under the License is distributed on an "AS IS" BASIS,
    14  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    15  See the License for the specific language governing permissions and
    16  limitations under the License.
    17  */
    18  
    19  package jsonsign
    20  
    21  import (
    22  	"errors"
    23  	"fmt"
    24  	"log"
    25  	"os"
    26  
    27  	"camlistore.org/pkg/misc/gpgagent"
    28  	"camlistore.org/pkg/misc/pinentry"
    29  	"camlistore.org/third_party/code.google.com/p/go.crypto/openpgp"
    30  )
    31  
    32  func (fe *FileEntityFetcher) decryptEntity(e *openpgp.Entity) error {
    33  	// TODO: syscall.Mlock a region and keep pass phrase in it.
    34  	pubk := &e.PrivateKey.PublicKey
    35  	desc := fmt.Sprintf("Need to unlock GPG key %s to use it for signing.",
    36  		pubk.KeyIdShortString())
    37  
    38  	conn, err := gpgagent.NewConn()
    39  	switch err {
    40  	case gpgagent.ErrNoAgent:
    41  		fmt.Fprintf(os.Stderr, "Note: gpg-agent not found; resorting to on-demand password entry.\n")
    42  	case nil:
    43  		defer conn.Close()
    44  		req := &gpgagent.PassphraseRequest{
    45  			CacheKey: "camli:jsonsign:" + pubk.KeyIdShortString(),
    46  			Prompt:   "Passphrase",
    47  			Desc:     desc,
    48  		}
    49  		for tries := 0; tries < 2; tries++ {
    50  			pass, err := conn.GetPassphrase(req)
    51  			if err == nil {
    52  				err = e.PrivateKey.Decrypt([]byte(pass))
    53  				if err == nil {
    54  					return nil
    55  				}
    56  				req.Error = "Passphrase failed to decrypt: " + err.Error()
    57  				conn.RemoveFromCache(req.CacheKey)
    58  				continue
    59  			}
    60  			if err == gpgagent.ErrCancel {
    61  				return errors.New("jsonsign: failed to decrypt key; action canceled")
    62  			}
    63  			log.Printf("jsonsign: gpgagent: %v", err)
    64  		}
    65  	default:
    66  		log.Printf("jsonsign: gpgagent: %v", err)
    67  	}
    68  
    69  	pinReq := &pinentry.Request{Desc: desc, Prompt: "Passphrase"}
    70  	for tries := 0; tries < 2; tries++ {
    71  		pass, err := pinReq.GetPIN()
    72  		if err == nil {
    73  			err = e.PrivateKey.Decrypt([]byte(pass))
    74  			if err == nil {
    75  				return nil
    76  			}
    77  			pinReq.Error = "Passphrase failed to decrypt: " + err.Error()
    78  			continue
    79  		}
    80  		if err == pinentry.ErrCancel {
    81  			return errors.New("jsonsign: failed to decrypt key; action canceled")
    82  		}
    83  		log.Printf("jsonsign: pinentry: %v", err)
    84  	}
    85  	return fmt.Errorf("jsonsign: failed to decrypt key %q", pubk.KeyIdShortString())
    86  }