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/
saltpack_decrypt.go
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/
saltpack_decrypt.go
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// Copyright 2015 Keybase, Inc. All rights reserved. Use of
// this source code is governed by the included BSD license.
package engine
import (
"bytes"
"io"
"github.com/keybase/client/go/libkb"
keybase1 "github.com/keybase/client/go/protocol/keybase1"
"github.com/keybase/saltpack"
"golang.org/x/net/context"
)
type SaltpackDecryptArg struct {
Source io.Reader
Sink io.WriteCloser
Opts keybase1.SaltpackDecryptOptions
}
// SaltpackDecrypt decrypts data read from a source into a sink.
type SaltpackDecrypt struct {
libkb.Contextified
arg *SaltpackDecryptArg
res keybase1.SaltpackEncryptedMessageInfo
}
// NewSaltpackDecrypt creates a SaltpackDecrypt engine.
func NewSaltpackDecrypt(arg *SaltpackDecryptArg, g *libkb.GlobalContext) *SaltpackDecrypt {
return &SaltpackDecrypt{
Contextified: libkb.NewContextified(g),
arg: arg,
}
}
// Name is the unique engine name.
func (e *SaltpackDecrypt) Name() string {
return "SaltpackDecrypt"
}
// GetPrereqs returns the engine prereqs.
func (e *SaltpackDecrypt) Prereqs() Prereqs {
return Prereqs{}
}
// RequiredUIs returns the required UIs.
func (e *SaltpackDecrypt) RequiredUIs() []libkb.UIKind {
return []libkb.UIKind{
libkb.SaltpackUIKind,
libkb.SecretUIKind,
}
}
// SubConsumers returns the other UI consumers for this engine.
func (e *SaltpackDecrypt) SubConsumers() []libkb.UIConsumer {
return []libkb.UIConsumer{
&SaltpackSenderIdentify{},
}
}
func (e *SaltpackDecrypt) promptForDecrypt(ctx *Context, publicKey keybase1.KID, isAnon bool) (err error) {
defer e.G().Trace("SaltpackDecrypt::promptForDecrypt", func() error { return err })()
spsiArg := SaltpackSenderIdentifyArg{
isAnon: isAnon,
publicKey: publicKey,
interactive: e.arg.Opts.Interactive,
forceRemoteCheck: e.arg.Opts.ForceRemoteCheck,
reason: keybase1.IdentifyReason{
Reason: "Identify who encrypted this message",
Type: keybase1.IdentifyReasonType_DECRYPT,
},
}
spsiEng := NewSaltpackSenderIdentify(e.G(), &spsiArg)
if err = RunEngine(spsiEng, ctx); err != nil {
return err
}
arg := keybase1.SaltpackPromptForDecryptArg{
Sender: spsiEng.Result(),
}
e.res.Sender = arg.Sender
usedDelegateUI := false
if e.G().UIRouter != nil {
if ui, err := e.G().UIRouter.GetIdentifyUI(); err == nil && ui != nil {
usedDelegateUI = true
}
}
err = ctx.SaltpackUI.SaltpackPromptForDecrypt(context.TODO(), arg, usedDelegateUI)
if err != nil {
return err
}
return err
}
func (e *SaltpackDecrypt) makeMessageInfo(me *libkb.User, mki *saltpack.MessageKeyInfo) {
if mki == nil || me == nil {
return
}
ckf := me.GetComputedKeyFamily()
for _, nr := range mki.NamedReceivers {
kid := keybase1.KIDFromRawKey(nr, libkb.KIDNaclDH)
if dev, _ := ckf.GetDeviceForKID(kid); dev != nil {
edev := dev.ProtExport()
edev.EncryptKey = kid
e.res.Devices = append(e.res.Devices, *edev)
}
}
e.res.NumAnonReceivers = mki.NumAnonReceivers
e.res.ReceiverIsAnon = mki.ReceiverIsAnon
}
// Run starts the engine.
func (e *SaltpackDecrypt) Run(ctx *Context) (err error) {
defer e.G().Trace("SaltpackDecrypt::Run", func() error { return err })()
// We don't load this in the --paperkey case.
var me *libkb.User
var key libkb.GenericKey
if e.arg.Opts.UsePaperKey {
// Prompt the user for a paper key. This doesn't require you to be
// logged in.
keypair, _, err := getPaperKey(e.G(), ctx, nil)
if err != nil {
return err
}
key = keypair.encKey
} else {
// Load self so that we can get device keys. This does require you to
// be logged in.
me, err = libkb.LoadMe(libkb.NewLoadUserArg(e.G()))
if err != nil {
return err
}
// Get the device encryption key, maybe prompting the user.
ska := libkb.SecretKeyArg{
Me: me,
KeyType: libkb.DeviceEncryptionKeyType,
}
e.G().Log.Debug("| GetSecretKeyWithPrompt")
key, err = e.G().Keyrings.GetSecretKeyWithPrompt(ctx.SecretKeyPromptArg(ska, "decrypting a message/file"))
if err != nil {
return err
}
}
kp, ok := key.(libkb.NaclDHKeyPair)
if !ok || kp.Private == nil {
return libkb.KeyCannotDecryptError{}
}
// For DH mode.
hookMki := func(mki *saltpack.MessageKeyInfo) error {
kidToIdentify := libkb.BoxPublicKeyToKeybaseKID(mki.SenderKey)
return e.promptForDecrypt(ctx, kidToIdentify, mki.SenderIsAnon)
}
// For signcryption mode.
hookSenderSigningKey := func(senderSigningKey saltpack.SigningPublicKey) error {
kidToIdentify := libkb.SigningPublicKeyToKeybaseKID(senderSigningKey)
// See if the sender signing key is all zeroes.
isAnon := bytes.Equal(senderSigningKey.ToKID(), make([]byte, len(senderSigningKey.ToKID())))
return e.promptForDecrypt(ctx, kidToIdentify, isAnon)
}
e.G().Log.Debug("| SaltpackDecrypt")
var mki *saltpack.MessageKeyInfo
mki, err = libkb.SaltpackDecrypt(ctx.GetNetContext(), e.G(), e.arg.Source, e.arg.Sink, kp, hookMki, hookSenderSigningKey)
if err == saltpack.ErrNoDecryptionKey {
err = libkb.NoDecryptionKeyError{Msg: "no suitable device key found"}
}
// It's ok if me is nil here.
e.makeMessageInfo(me, mki)
return err
}
func (e *SaltpackDecrypt) MessageInfo() keybase1.SaltpackEncryptedMessageInfo {
return e.res
}