/
saltpack_dec.go
86 lines (72 loc) · 2.37 KB
/
saltpack_dec.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 libkb
import (
"io"
"github.com/keybase/saltpack"
)
func getStatusCodeFromDecryptionError(err *DecryptionError) (code int) {
switch err.Cause.Err.(type) {
case APINetError:
code = SCAPINetworkError
case saltpack.ErrNoSenderKey:
code = SCDecryptionKeyNotFound
case saltpack.ErrWrongMessageType:
code = SCWrongCryptoMsgType
}
return code
}
func SaltpackDecrypt(m MetaContext, source io.Reader, sink io.WriteCloser,
decryptionKeyring saltpack.SigncryptKeyring,
checkSenderMki func(*saltpack.MessageKeyInfo) error,
checkSenderSigningKey func(saltpack.SigningPublicKey) error,
keyResolver saltpack.SymmetricKeyResolver) (mki *saltpack.MessageKeyInfo, err error) {
defer func() {
if derr, ok := err.(DecryptionError); ok {
derr.Cause.StatusCode = getStatusCodeFromDecryptionError(&derr)
err = derr
}
}()
sc, newSource, err := ClassifyStream(source)
if err != nil {
return nil, err
}
if sc.Format != CryptoMessageFormatSaltpack {
return nil, WrongCryptoFormatError{
Wanted: CryptoMessageFormatSaltpack,
Received: sc.Format,
Operation: "decrypt",
}
}
source = newSource
// mki will be set for DH mode, senderSigningKey will be set for signcryption mode
plainsource, typ, mki, senderSigningKey, isArmored, brand, _, err := saltpack.ClassifyEncryptedStreamAndMakeDecoder(source, decryptionKeyring, keyResolver)
if err != nil {
return mki, DecryptionError{Cause: ErrorCause{Err: err}}
}
if typ == saltpack.MessageTypeEncryption && checkSenderMki != nil {
if err = checkSenderMki(mki); err != nil {
return mki, DecryptionError{Cause: ErrorCause{Err: err}}
}
}
if typ == saltpack.MessageTypeSigncryption && checkSenderSigningKey != nil {
if err = checkSenderSigningKey(senderSigningKey); err != nil {
return nil, DecryptionError{Cause: ErrorCause{Err: err}}
}
}
n, err := io.Copy(sink, plainsource)
if err != nil {
return mki, DecryptionError{Cause: ErrorCause{Err: err}}
}
if isArmored {
// Note: the following check always passes!
if err = checkSaltpackBrand(brand); err != nil {
return mki, DecryptionError{Cause: ErrorCause{Err: err}}
}
}
m.Debug("Decrypt: read %d bytes", n)
if err := sink.Close(); err != nil {
return mki, DecryptionError{Cause: ErrorCause{Err: err}}
}
return mki, nil
}