117 lines
2.9 KiB
Go
117 lines
2.9 KiB
Go
// Copyright 2018 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 encryption
|
|
|
|
import (
|
|
"crypto/rand"
|
|
"encoding/binary"
|
|
"fmt"
|
|
"hash"
|
|
)
|
|
|
|
const KeyLength = 32
|
|
|
|
type Key []byte
|
|
|
|
type Encryption interface {
|
|
Encrypt(data []byte, key Key) ([]byte, error)
|
|
Decrypt(data []byte, key Key) ([]byte, error)
|
|
}
|
|
|
|
type encryption struct {
|
|
padding int
|
|
initCtr uint32
|
|
hashFunc func() hash.Hash
|
|
}
|
|
|
|
func New(padding int, initCtr uint32, hashFunc func() hash.Hash) *encryption {
|
|
return &encryption{
|
|
padding: padding,
|
|
initCtr: initCtr,
|
|
hashFunc: hashFunc,
|
|
}
|
|
}
|
|
|
|
func (e *encryption) Encrypt(data []byte, key Key) ([]byte, error) {
|
|
length := len(data)
|
|
isFixedPadding := e.padding > 0
|
|
if isFixedPadding && length > e.padding {
|
|
return nil, fmt.Errorf("Data length longer than padding, data length %v padding %v", length, e.padding)
|
|
}
|
|
|
|
paddedData := data
|
|
if isFixedPadding && length < e.padding {
|
|
paddedData = make([]byte, e.padding)
|
|
copy(paddedData[:length], data)
|
|
rand.Read(paddedData[length:])
|
|
}
|
|
return e.transform(paddedData, key), nil
|
|
}
|
|
|
|
func (e *encryption) Decrypt(data []byte, key Key) ([]byte, error) {
|
|
length := len(data)
|
|
if e.padding > 0 && length != e.padding {
|
|
return nil, fmt.Errorf("Data length different than padding, data length %v padding %v", length, e.padding)
|
|
}
|
|
|
|
return e.transform(data, key), nil
|
|
}
|
|
|
|
func (e *encryption) transform(data []byte, key Key) []byte {
|
|
dataLength := len(data)
|
|
transformedData := make([]byte, dataLength)
|
|
hasher := e.hashFunc()
|
|
ctr := e.initCtr
|
|
hashSize := hasher.Size()
|
|
for i := 0; i < dataLength; i += hashSize {
|
|
hasher.Write(key)
|
|
|
|
ctrBytes := make([]byte, 4)
|
|
binary.LittleEndian.PutUint32(ctrBytes, ctr)
|
|
|
|
hasher.Write(ctrBytes)
|
|
|
|
ctrHash := hasher.Sum(nil)
|
|
hasher.Reset()
|
|
hasher.Write(ctrHash)
|
|
|
|
segmentKey := hasher.Sum(nil)
|
|
|
|
hasher.Reset()
|
|
|
|
segmentSize := min(hashSize, dataLength-i)
|
|
for j := 0; j < segmentSize; j++ {
|
|
transformedData[i+j] = data[i+j] ^ segmentKey[j]
|
|
}
|
|
ctr++
|
|
}
|
|
return transformedData
|
|
}
|
|
|
|
func GenerateRandomKey() (Key, error) {
|
|
key := make([]byte, KeyLength)
|
|
_, err := rand.Read(key)
|
|
return key, err
|
|
}
|
|
|
|
func min(x, y int) int {
|
|
if x < y {
|
|
return x
|
|
}
|
|
return y
|
|
}
|