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// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package api
import (
"encoding/binary"
"errors"
"github.com/ethereum/go-ethereum/crypto/sha3"
"github.com/ethereum/go-ethereum/swarm/storage/encryption"
)
type RefEncryption struct {
spanEncryption encryption.Encryption
dataEncryption encryption.Encryption
span []byte
}
func NewRefEncryption(refSize int) *RefEncryption {
span := make([]byte, 8)
binary.LittleEndian.PutUint64(span, uint64(refSize))
return &RefEncryption{
spanEncryption: encryption.New(0, uint32(refSize/32), sha3.NewKeccak256),
dataEncryption: encryption.New(refSize, 0, sha3.NewKeccak256),
span: span,
}
}
func (re *RefEncryption) Encrypt(ref []byte, key []byte) ([]byte, error) {
encryptedSpan, err := re.spanEncryption.Encrypt(re.span, key)
if err != nil {
return nil, err
}
encryptedData, err := re.dataEncryption.Encrypt(ref, key)
if err != nil {
return nil, err
}
encryptedRef := make([]byte, len(ref)+8)
copy(encryptedRef[:8], encryptedSpan)
copy(encryptedRef[8:], encryptedData)
return encryptedRef, nil
}
func (re *RefEncryption) Decrypt(ref []byte, key []byte) ([]byte, error) {
decryptedSpan, err := re.spanEncryption.Decrypt(ref[:8], key)
if err != nil {
return nil, err
}
size := binary.LittleEndian.Uint64(decryptedSpan)
if size != uint64(len(ref)-8) {
return nil, errors.New("invalid span in encrypted reference")
}
decryptedRef, err := re.dataEncryption.Decrypt(ref[8:], key)
if err != nil {
return nil, err
}
return decryptedRef, nil
}
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