/
utils.go
52 lines (49 loc) · 1.69 KB
/
utils.go
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// Copyright 2016, Cossack Labs Limited
//
// 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 base
import (
"bytes"
"encoding/binary"
"github.com/cossacklabs/acra/utils"
"github.com/cossacklabs/themis/gothemis/cell"
"github.com/cossacklabs/themis/gothemis/keys"
"github.com/cossacklabs/themis/gothemis/message"
)
const (
LENGTH_SIZE = 8
)
func DecryptAcrastruct(data []byte, privateKey *keys.PrivateKey, zone []byte) ([]byte, error) {
innerData := data[len(TAG_BEGIN):]
pubkey := &keys.PublicKey{Value: innerData[:PUBLIC_KEY_LENGTH]}
smessage := message.New(privateKey, pubkey)
symmetricKey, err := smessage.Unwrap(innerData[PUBLIC_KEY_LENGTH:KEY_BLOCK_LENGTH])
if err != nil {
return []byte{}, err
}
//
var length uint64
// convert from little endian
err = binary.Read(bytes.NewReader(innerData[KEY_BLOCK_LENGTH:KEY_BLOCK_LENGTH+LENGTH_SIZE]), binary.LittleEndian, &length)
if err != nil {
return []byte{}, err
}
scell := cell.New(symmetricKey, cell.CELL_MODE_SEAL)
decrypted, err := scell.Unprotect(innerData[KEY_BLOCK_LENGTH+LENGTH_SIZE:], nil, zone)
// fill zero symmetric_key
utils.FillSlice(byte(0), symmetricKey)
if err != nil {
return []byte{}, err
}
return decrypted, nil
}