github.com/divan/go-ethereum@v1.8.14-0.20180820134928-1de9ada4016d/swarm/api/encrypt.go (about)

     1  // Copyright 2016 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package api
    18  
    19  import (
    20  	"encoding/binary"
    21  	"errors"
    22  
    23  	"github.com/ethereum/go-ethereum/crypto/sha3"
    24  	"github.com/ethereum/go-ethereum/swarm/storage/encryption"
    25  )
    26  
    27  type RefEncryption struct {
    28  	spanEncryption encryption.Encryption
    29  	dataEncryption encryption.Encryption
    30  	span           []byte
    31  }
    32  
    33  func NewRefEncryption(refSize int) *RefEncryption {
    34  	span := make([]byte, 8)
    35  	binary.LittleEndian.PutUint64(span, uint64(refSize))
    36  	return &RefEncryption{
    37  		spanEncryption: encryption.New(0, uint32(refSize/32), sha3.NewKeccak256),
    38  		dataEncryption: encryption.New(refSize, 0, sha3.NewKeccak256),
    39  		span:           span,
    40  	}
    41  }
    42  
    43  func (re *RefEncryption) Encrypt(ref []byte, key []byte) ([]byte, error) {
    44  	encryptedSpan, err := re.spanEncryption.Encrypt(re.span, key)
    45  	if err != nil {
    46  		return nil, err
    47  	}
    48  	encryptedData, err := re.dataEncryption.Encrypt(ref, key)
    49  	if err != nil {
    50  		return nil, err
    51  	}
    52  	encryptedRef := make([]byte, len(ref)+8)
    53  	copy(encryptedRef[:8], encryptedSpan)
    54  	copy(encryptedRef[8:], encryptedData)
    55  
    56  	return encryptedRef, nil
    57  }
    58  
    59  func (re *RefEncryption) Decrypt(ref []byte, key []byte) ([]byte, error) {
    60  	decryptedSpan, err := re.spanEncryption.Decrypt(ref[:8], key)
    61  	if err != nil {
    62  		return nil, err
    63  	}
    64  
    65  	size := binary.LittleEndian.Uint64(decryptedSpan)
    66  	if size != uint64(len(ref)-8) {
    67  		return nil, errors.New("invalid span in encrypted reference")
    68  	}
    69  
    70  	decryptedRef, err := re.dataEncryption.Decrypt(ref[8:], key)
    71  	if err != nil {
    72  		return nil, err
    73  	}
    74  
    75  	return decryptedRef, nil
    76  }